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PostPosted: Sat Mar 07, 2009 6:02 pm 
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This is a long thread which covers most of the "How-To's" of the Hitachi.
A small post has been added at the end on accelerator pump repair, but the thread is by no means a complete repair guide, and is not a 'step-by-step' process.
Fixing these carburetors is one of my hobbies,
viewtopic.php?f=15&t=38699
and I've yet to find one I couldn't fix.

These cars will give you dollars for every cent you spend on them; show some appreciation to the people who saved you ($450 as of the editing of this post) for a rebuilt carb. Asking for help with a Hitachi carb on this forum and then buying carb parts and kits from vendors who are not members doesn't necessarily make you a 'cheap bastard', a 'slick prick', or an 'ungrateful slob', but it does call into question your integrity. Let me put it another way... don't ask for advice, go elsewhere for parts, and then thank us... Bite the bullet, man up, and kick in the extra bucks for the parts your helpers/fellow board members sell. Then get your money back in years of driving pleasure.
Show your fellow forum members and the car some respect, and we'll get along fine.

Have a nice read:


Here's a way to avoid having to pull the carb apart once you've put it all back together...and then you find the float level is off. This technique is necessary because modern carb repair kits often have NON-OEM parts which different needle valves and seats, making the 'measuring stick method' obsolete.

First, you have to know when the float level is right.
On the right side of the car, you can look and see a sight glass. It's #22 in the drawing below. There should be a line about half way where the gas level remains, even when the car is idling. If the car doesn't run right, and there's no line in the sight glass, then you will have to adjust the float.
If you look and can't see the level, maybe the float is stuck open, and this will flood the engine. If the float is stuck closed, again, you won't see the fuel level in the sight glass. Of course, the engine won't start.
This is an easy way to find out if the fuel pump is not working, or the fuel filters are clogged, or you are simply out of gas. And it is the FIRST thing you should check. If you can't answer this question, you need to stop and ask yourself if you are serious about fixing the car.
Let's suppose you decide to pull the carb and fix the float level. You can use this diagram to pull the carb off the car and take it apart:
Image

...but how about putting it back together right the first time?

Let's say you get it to this point:

Image
Here, you've cleaned the body and base and are starting to put it back together.
The 'Fuel Cut Solenoid' is screwed into place, and there's a new gasket on the body.
Next, before you install a new Mixture Control Solenoid, you need to set the float level.
Image
Get your seat and screen (sorry for the blurry picture) and the little gasket that should come with most rebuild kits, and put them into the cover:
Image
Now you get your needle valve and clip
(next three images are a bit blurry, but you can get the idea):
Image
First, the clip is put on the needle valve, and then the valve clips on to the float:
Image
Now, the whole thing gets put on the cover, upside down:
Image
All you have to do is put the cover on the body of the carb. Don't install the acclerator pump or Mixture Control Solenoid just yet.

Next, you take it outside, and plug one of the fuel inlets, and run gasoline into the other
(notice the bowl vent solenoid isn't even hooked up yet):
Image
Here is a little plastic container which comes with most vacuum pump sets. It's got a fuel line running to the carb inlet. Simply lift the container up, and tilt it. Watch the site glass. Once the level settles out, you can even apply a little pressure to the other side of the container to simulate a fuel pump.
Now you can easily go back and forth, bending the tang on the float if necessary to get the correct level in your glass.
Once you're done, just take the top back off, and remove the gasket. Then you can pour the gas back into the container. Now you can continue by removing the float and valve carefully, and setting them aside.
Then put the Mixture Control Solenoid into place:
Image
using a tiny bit of silicone-based lubricant.
Don't forget to put a little bit on the other O-ring before you put the top back on.
If you've removed the Bowl Vent Solenoid, there are two O-rings which can be easily replaced. Here, it's been installed:
Image
Now would be a good time to check that Bowl Vent Solenoid. It may click when you hit it with 12 volts, but is the plunger retracting? If the carb has been sitting for awhile, the plunger can get stuck on the vent seat.
Gently free it with a screwdriver, and you should be good to go.
Now you can put your float back in place carefully, and install a rebuilt accelerator pump:
Image
The pump on the left has been rebuilt.
Maybe someone could make a DIY Accelerator Pump Rebuild thread for posterity?
Make sure parts 49 thru 53 in the diagram above are in place. Then proceed like this:
Once your float is back in place, carefully put the top on the carb. You should end up with something that looks like this:
Image

Hopefully, this will save some of you a lot of headaches realizing (too late) that your float adjustments are off. Check those sight glasses, especially if you haven't in a while and she isn't running like she used to!!!
Too many people have given up on these cars because there was no DIY Carb Rebuild/Reassembly thread.
These carbs are easy, if you read through the above, and take it one step at a time.

(Title edited to reflect addition of the posts by mkc1962 covering 'cleaning and rebuilding the body'.)

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DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
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DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


Last edited by Phil N Ed on Tue Apr 26, 2011 2:20 pm, edited 2 times in total.

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PostPosted: Sat Mar 07, 2009 7:26 pm 
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excellent :alien: :alien: :alien: :alien: :alien:

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looking for:
the time i mispent in my youth

daily driver: red 1991 Metro 3cyl 5sp, roof rack, 8 degree advance,
got 61 mpg combined on 14" tires but i prefer 12"

completed frame up restoration: black 1994 Swift GT 5sp -- like new ! 45mpg


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PostPosted: Sat Mar 07, 2009 11:34 pm 
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Location: Emerald city Washington
.
That is smart and so simple ..NICE.!
.

But I'm telling you evertime I pull these carb apart
replace the o-rings and gaskets it always has vacume leaks.
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Just wanted to adds some pictures
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here i made a simple stand to hold the carb & my carb stx
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Image
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Image
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you can adjust the float on the car use a fine messure stix and adjust by MM at a time till you get it spot on
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Image
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note the float has a line on it but you can use the bottom edge farthest away from the seat
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Image
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yes i used the vac- tool bowl to charge the carb bowl to see were the float level
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Image
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.


Last edited by jaguar,vettes&sprints on Mon Nov 08, 2010 10:21 pm, edited 1 time in total.

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PostPosted: Sun Mar 08, 2009 6:50 pm 
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Thanks !!
Reminds me of the old rochesters, only with some extra electricals thrown in .
Can some of these electrical devices be eliminated or bypassed .
My thought is if some of these cars don't even come with computers , are all the electricals necessary ?
This of course applies only to the carburated motors ?
slick


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PostPosted: Sun Mar 08, 2009 8:11 pm 
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I think the float bowl vent could be eleminated just open vent to the char, can,

But not any of the other electronics
The MCS (mixture control solenoid) strokes about 20 times a second (it's the magic that makes these carb get 50+mpg)
And the fuel cut off solenoid thats tied into the Idle down curcit
Also the Wide open micro switch
And the Idle micro switch
.
Not many can work over these carb they are a little tricky phil and Mrs C. did my Forsa carb and I'm very happy with it
run's great and looked like new
.
.
....JV&S
.
.
Image


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PostPosted: Sun Mar 08, 2009 9:51 pm 
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Here's a little picture for you:
Image
Normally, there should be a vent hole at #1.
Apparently, someone just stuck a screw in there.
That vent hole goes to the MCS. With it plugged like that, the MCS can't get the air that it needs to mix with the fuel. So...if you see a carb like that, you know it won't run right. That carb will have to be looked at closely. Guess it will be my next project.

Number 2 is the Bowl vent solenoid. When it's shut, the gas in the bowl of the carburetor (where the float is) gets an opportunity to evaporate SLOWLY into the charcoal cannister.
If it's open (the plunger retracts when you hit it with 12 volts) the air can enter from #3 and go into the bowl. So, if you unplug the bowl vent solenoid, or the plunger gets stuck (from sitting a long time) you will not vent the fuel that you can see inside the sight glass. Your engine won't run right.

If the bowl vent solenoid is working properly (they rarely go bad) it is a win/win situation. You can park the car for months, and there will probably still be fuel in the carb. If you defeat this device, and vent the bowl to the atmosphere all the time, your gas will evaporate more quickly, especially in a warm engine/warm environment.

The cars with this carburetor have a ECM/'Computer'/Brain. There are a lot of things that it does.
Although it is simple looking back, at the time it was the most complex of the carbs built and uses information from many different sensors. They really put some thought into the whole system, and the result was a great all-around driveable vehicle. Few people realize how many sensors and 'programs' are built into our old carburetor models. Just a quick example would be the Idle Up Actuator. If you've ever wondered why even the old MK1's (85-88) don't idle down immediately at a stop sign, it's because the speed sensor inside the speedometer sends a signal to the ECM which tells the Idle Up Actuator to hold the engine speed a little above idle for about 3 seconds once you finally come to a complete stop. That same Idle Up Actuator can be seen going into action when the lights are turned on, or the heater, or the radiator fan. It also fluctuates depending on the signal received from the oxygen sensor. That's why sometimes it's hard to set the warm idle on these old cars. The idle up actuator is kicking in and out! You have to be patient and wait til it settles down sometimes.

Once you go through one of these carbs, set it up and get your car on line, you can expect it to give you years and years of trouble free service. Sadly, few people still know how to work on them. But this thread can get you most of the information you need to get your carb dialed in.

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DIY Wheel Bearings: viewtopic.php?f=2&t=29003
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DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


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PostPosted: Sat Jun 19, 2010 11:33 pm 
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The next 'DIY Carb Rebuild' installment should be something along the lines of:
"How to rebuild your accelerator pump"

Any takers?

Edited to add:
Next time I rebuild an accelerator pump, I'll try and take some pictures.
Here's what I'm talking about:
Image
Going from the old (on the right) to the rebuilt (on the left) is not a piece of cake.
Here you can see one that was ruined in the rebuild process (on the left):
Image
...the accelerator pump on the right is still rebuildable, the one on the left is trash.
The rebuild kit is that funny two piece set in the little separate plastic (on the right).
One simple mistake and you've ruined your carburetor, unless you can find another accelerator pump.
Here's another view; the one on the top is trash, the bottom one can still be rebuilt:
Image
There's a trick to changing those accelerator pump seals...anyone care to explain?
Hint: Do not attempt to pry that brass screen off the pump (lower white arrow) with a screwdriver!!!

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DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
DIY Wheel Bearings: viewtopic.php?f=2&t=29003
DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


Last edited by Phil N Ed on Tue Jul 06, 2010 10:52 am, edited 1 time in total.

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PostPosted: Tue Jul 06, 2010 6:04 am 
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great article, thanks.


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PostPosted: Wed Aug 04, 2010 3:20 am 
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Good information. I have rebuilt many hundreds of carbs in my life, but never looked close at one of these. Never saw a stock carb with a sight glass for checking fuel level either. So what is the "trick" to removing the screen holder? What is wrong with the one on the left? :? . From the picture, I can't tell, never having seen this type in person. I bet I could fix it though, and if not, machine up a whole new assembly from some brass stock. My experience with full time venting the bowl to atmosphere is that the fuel evaporates and leaves a gummy residue in the bottom, that clogs up the accel pump and idle circuit holes if you don't drive the car often enough. I will no doubt be rebuilding one of these carbs, when I find a motor for my project, so don't leave me hanging. :wink:
SA


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PostPosted: Wed Aug 04, 2010 12:43 pm 
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steeve wrote:
Good information. I have rebuilt many hundreds of carbs in my life, but never looked close at one of these. Never saw a stock carb with a sight glass for checking fuel level either. So what is the "trick" to removing the screen holder? What is wrong with the one on the left? :? . From the picture, I can't tell, never having seen this type in person. I bet I could fix it though, and if not, machine up a whole new assembly from some brass stock. My experience with full time venting the bowl to atmosphere is that the fuel evaporates and leaves a gummy residue in the bottom, that clogs up the accel pump and idle circuit holes if you don't drive the car often enough. I will no doubt be rebuilding one of these carbs, when I find a motor for my project, so don't leave me hanging. :wink:
SA

The next time I rebuild an accelerator pump, I'll take a picture of the hollow brass stem which most people accidentally break.
The pump on the left:
Image
has no such hollow brass stem (typical broken pump). The pump on the right has the stem, accelerator seal, and screen assembly intact, waiting to be rebuilt.
You won't be left hanging; when I have a picture of the technique, I'll post it.
Which model carburetors have you rebuilt (eg. Stromberg 97, Rochester 4-jet, Rochester Quadrajet, Holley 650)?

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DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


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PostPosted: Wed Aug 04, 2010 5:01 pm 
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Thanks Phil, I have done all of the above carbs and more. I also contracted to an OEM for carb development work, designed and built my own carbs, and after mkt replacement parts for Holly. I might even build a horizontal flat slide version to try on the Sprint motor; They have a very efficient variable venturi, that really works great at low throttle openings for fuel economy; even better than CVs. No need for multiple throttle valves or acel pumps in most cases.
Cheers


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PostPosted: Tue Sep 14, 2010 7:36 pm 
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Yep, DukeNukem the Mighty Vac is a big help.
Fal went out and bought one and when I arrived to help with his engine
viewtopic.php?f=31&t=48845
he had exactly the same problem as you described - the sight glass was full and you could smell gas inside the engine compartment.
You should have heard him when we used this procedure to reset the float level.
I thought we'd wake the neighbors!!!!

Now it runs a lot better, or so I'm told.

'Course that race grind from Suprf1y might have something to do with it!

:huh: :wink: :huh: :wink: :huh: :wink:

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DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
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DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


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PostPosted: Mon Oct 04, 2010 10:12 pm 
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This thread is 'bench work'. You want to pull the carburetor and do this on a bench (above, I used a Ducane Barbeque).

No one volunteers to do an accelerator pump rebuild DIY?
(Usually you can just reuse your old one.)

A couple of things come to mind, and I thought I'd add them to this thread.
(We are talking about the USA Hitachi carburetor...)

First, the Float Adjustment, using the technique that Fal, Duke Nukem and I have explained is necessary because the replacement float valves and seats are not OEM. Aftermarket kits, which may supply these parts will also include a set of instructions with measurements. Unfortunately, the little washer which goes under the seat, as well as the seat and needle heights vary. So you can't use a measuring device and get accurate results. It's better to do it like we've outlined above, and it will take a bit longer, but is the most commonly overlooked and most common problem with the 85-88 carbureted Chevy Sprints.

Second, the Mixture Control Solenoid (MCS): The second most common problem with these carburetors is the MCS.
It is a bit expensive, but you will notice an immediate improvement once you install one. Figure that they can last for years, but the previous owner never bothered. So with time, the MCS' performance will deteriorate. There is a special tool mentioned to extract the wires from the power pack fitting here:

viewtopic.php?f=31&t=31555

Third, the Bowl Vent Solenoid (BVS): The third most common problem I've encountered with these carburetors is the BVS. It usually is an easy (and free) fix. The BVS works, but the rubber seal at the end of the piston sometimes gets stuck. You can simply unstick it, and you should be good to go.

Fourth: The secondaries are not opened by a progressive push of the gas pedal (like a Holley, for example).
The secondary butterfly is opened by a vacuum diaphragm which is plugged directly into the carburetor. Often a vacuum leak at that location goes undetected. You will hear, "I get GREAT mileage!". Yep. He gets great mileage because only half the carburetor is working. =) =) =)

Fifth: Sometimes the 'Choke Pull Off' will leak. Again, we're talking vacuum. You will have to find a replacement, either in a junkyard or ????

Sixth: One very unusual problem I've run across is the gaskets under the carburetor. There is supposed to be an insulator below the carburetor (thick piece of 'plastic'). Above and below it are two DIFFERENT gaskets. Recently, someone was having problems with their car, and no amount of PMs could repair the problem. When I took off the carburetor, I found that the local mechanic had used the gaskets in the generic rebuild kit, but had put two of the same gaskets on the insulator - one above and one below. Again, the insulator should be fitted on the intake manifold with two DIFFERENT gaskets.

Seventh: The Choke - When you put the top on the carburetor, notice that you keep the linkage 'sprung' via a drill inserted into two holes exactly for this purpose. Once the top is screwed down, you carefully open the throttle and the drill easily comes out. Be careful not to screw up the choke linkage. The car does not have 'step down' throttle linkage. So you adjust the cold idle, and as the car warms up, the idle will slowly return to the 850 rpms or whatever the under hood sticker calls for.

Eighth: Warm Idle - Once you've adjusted the cold idle, allow the car to warm up and adjust the 'warm idle'. It is a different screw. Too many people make a mistake and use the cold idle screw to adjust the warm idle.
There is a picture of a carburetor with several screws labeled; perhaps we should like to that photo?

Ninth: Idle mixture - You have the vehicle warm, and idling correctly? Then set the idle mixture according to the Carb Manual. Obviously, it might be necessary to go back and forth between the warm idle and idle mixture screws.

Tenth: Tools to make your job a success - For cleaning the carb, you will need a toothbrush and some Simple Green, rinse with water and blow dry with some air. To remove the stubborn Phillips screws, you should have a good (ie Craftsman) impact driver. To check the vacuum solenoids and set the float you should have a vacuum tester.
Duke Nukem and Fal used the Mighty Vac, and that unit is nice because it has the little chamber shown above which we used to fill with gas and set the float. But you can use any unit you like. The 12 MM wrench to pull the carb and put it back on the intake manifold sometimes gets a torch and bent, but mine is just a cheapo regular 12 MM open/box combination wrench. You'll need a small drill bit to hold the linkage open, and one to drill out the idle mixture screw plug. For checking the electronics, you can use a $5 digital ohm/voltmeter.

Eleven: Vacuum Solenoids to check with your vacuum tester - (total time: 10 mins max)
-idle up actuator
-choke pull off
-secondary diaphragm
-second air valve
-vacuum advance at the distributor
-EGR vacuum at the valve
-3 way solenoid valve (with black lead wire)
-3 way solenoid valve (with blue lead wire)

Twelve: Electrical devices to check with your DOVM - (total time: 15 mins max)
-bowl vent solenoid
-mixture control solenoid
-fuel cut solenoid
-idle microswitch
-wide open microswitch

In conclusion (whew!) old Suzuki built a vehicle which is COMPLETELY serviceable by the home mechanic if he takes his time and pays attention to details. It is very inexpensive to repair these carburetors, and keep your car running in tip top shape. It is also much easier to troubleshoot the Hitachi carburetor than you initially might think, as the OBD I system has a warning system built in. If you have no 'codes', it means that all the sensors are hooked up. Once you've taken the time to go over each and every system built into the carburetor, it will be much easier to look at the next time. In the long run, you will find it easier to maintain these carburetors than to replace them with aftermarket units which do not use the 'feedback mechanisms' described in the manual.
If the link is still working, you can read the manual in order here:

http://s145.photobucket.com/albums/r211 ... ?start=all

You want to squeeze the most out of every gallon you put in your tank? Take the carburetor off that $50/freebie car, and go through it! As of this post, a rebuilt carburetor will cost you in excess of $400.

_________________
DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
DIY Wheel Bearings: viewtopic.php?f=2&t=29003
DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


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PostPosted: Fri Oct 29, 2010 9:16 am 
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Although we haven't had any takers on the challenge to post an 'accelerator pump rebuild' post in this thread, we have had a new member read this thread, rebuild his carburetor, and describe his experiences. He successfully rebuilt his accelerator pump.

You can read about it here:
viewtopic.php?p=369318#p369318

Quote:
Rebuilding the accelerator pump took some finesse. I took a box cutter blade and cut the rubber plunger off and then wrapped the body of the pump with a cloth rag and grabbed the body with channel locks, I then very gingerly turned the pump cap with a pair of needle nose (very careful to not kink it on the shaft) while pulling upward. Once I put the new plunger on I put a rag over the top of the cap and the bottom of the main pump body and used channel locks to press the cap on. I probably could have taken different measures to ensure safety but it worked so I'm fine with my methods


Skamaniak's method of accelerator pump disassembly is a bit scary and the easiest way to break the pump.

Accelerator pumps generally last a long time, and rarely need to be rebuilt.

Again, here are the two pieces you are replacing when you rebuild an accelerator pump:
Image
1. He's putting on the blue and brass colored pieces to the right in the picture above.
2. The top white arrow shows what happens when you break an accelerator pump.
3. That particular pump was broken when someone used a screwdriver to pry up on the space indicated by the lower white arrow.
4. The black (2 pieces) rubber is the old, removed plunger...equivalent to the new blue piece.

The lower pump is still rebuildable, the upper pump is fish line weight.

Any better suggestions on how to remove the brass piece to the right of the lower white arrow?

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DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


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PostPosted: Sun Apr 10, 2011 1:28 pm 
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It is time to update this carb rebuild thread.
As a reminder, in order of probable problems, follow this 'flow chart':
1.) vacuum leaks
2.) float out of adjustment
3.) needle valve (worked by float) sticking
4.) MCS

Unusual (unlikely) problems, in no specific order:
-bad microswitch
-bad fuel cut or bowl vent solenoid
-stuck plunger on the two solenoids above
-primary butterfly rod sucking air

If you are still having problems, then you probably need to take the carb apart, clean it, and put it back together. Here is the post where this procedure is illustrated:
viewtopic.php?p=378427#p378427
and a thanks to mkc1962 for posting that.

Remember to follow his instructions carefully, especially the part about drilling the 'plug'.

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DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
DIY Wheel Bearings: viewtopic.php?f=2&t=29003
DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


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PostPosted: Sun May 01, 2011 12:11 pm 
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Where you see 'vacuum leaks' (#1 above), it might not be clear.
Let's illustrate.
This will have an added advantage for those who think you need to rebuild the carburetor, when it is actually OK.
First, let's test the 'vacuum holding' capacity of the choke pull off.
Here is how you do it:
Image
There is no need to pull a huge vacuum; just put the needle up there and see that it holds steady.
If you have to keep squeezing your vacuum tester to get the needle up and it won't hold still, then you have a leak.
As you can see from the pictures, no one is holding the tool and the needle stays in one place.

Next, let's do the secondary diaphragm:
Image
Again, this is a simple procedure and we are looking for a steady needle at about the 3 o'clock position.

Last, let's do the idle up actuator:
Image
The vacuum tester is all the way out towards the hood prop rod, and you are checking the line all the way from the vacuum switch to the idle up actuator.

This completes the checks of the 'vacuum pots' on the carburetor. If all of the needles hold steady, you have a rebuildable carburetor / good core.

Moving away from the carburetor, you can continue to check for vacuum leaks.
You can easily check the second air valve, using the line directly above the one you just checked.

Once that is done, you can check the two or three (depending on your car) lines coming from the gas filter.
The 'gas filter' (not 'fuel filter') is just below the secondary diaphragm and is screwed into the intake manifold.
Don't skip this step.
Suppose you sniff the tailpipe and see high CO and maybe high HC. Don't jump to the conclusion that your carburetor is dumping too much fuel into the engine (it is, but read on).
Note that if the vacuum switch to the second air valve leaks, you will create a rich condition in your engine.
Why?
The second air valve will remain on, sending fresh air to the exhaust, so your oxygen sensor will continuously yield 0 volts instead of the .8 volts it needs to lean out the MCS in the carb.
In this condition, you can get the car to pass emissions by installing a new catalytic converter (band aid fix), but by fixing that valve, you will get the carburetor to work properly again (fixing the 'root' of the problem).
This is just one illustration why your carburetor 'woes' might not be fixed with a plug and play rebuilt carburetor.
In the case above, the problem wasn't the carburetor or a carburetor adjustment, but one of the little vacuum switches on the side. :thumb2:
You need to investigate all the systems on the MK1, and will be pleased with the final result.

Now that we have finished with the front of the carburetor and possible vacuum leaks, there are several on the back. (five to seven, depending on how you count and what year and model).
But you're probably bored with this post, so if you have an MK1, go out and spend 30 minutes and check all those front and side lines, especially if she doesn't hold all rpms smooth as glass.
We'll look at those rear vacuum lines another time, or one of you can go ahead and shoot up a little carb help.

_________________
DIY Broken Bolt Removal: viewtopic.php?f=22&t=41042
DIY Clutch Adjustment: viewtopic.php?f=9&t=48281
DIY Wheel Bearings: viewtopic.php?f=2&t=29003
DIY Shocks: viewtopic.php?f=10&t=45483
DIY Wheel Align: viewtopic.php?f=2&t=42479
Once you get the cars dialed-in (compression, leaks, bearings, alignment, brakes) swap in new rubber and glass, you've got something which should last for years!


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PostPosted: Tue Oct 31, 2017 12:39 am 
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Posts: 2
Location: British columbia
Tons of great info here Phil.. ive been trolling for sometime now and greatly appreciate your presence and knowledge around here..
Im about to take my carb apart next week and clean her out as im only getting around 25 mpg now.. its been a 6 month steady decline down from the famous 52mpg..
and would love to be able to see all the pics in the above links. But They are not working anymore..
Are they on your photobucket account still or have they been long deleted?
Id give my right leg to be able to see all.these pics that aren't working anymore :cry:


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PostPosted: Tue Oct 31, 2017 4:39 am 
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The pictures are stored on Photobucket, a site which tried to get rich quick a couple of months ago by charging a huge ransom for people's pics. If you use Chrome or Firefox there is an add on which makes these work again. Just search "Photobucket fix", pick your browser, and install.

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PostPosted: Tue Oct 31, 2017 10:28 am 
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Location: British columbia
Thanks for the heads up. Woodie..
Greatly appreciated.


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