TeamSwift

has anybody used an electric fuel pump on the stock carb? i am not talking about EFI pumps that put out 50psi, more like the holly pumps that put out 10 psi or so. has anybody done this?
thanks,
nemo

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"muchos tanks, village destruidos"
"muchos sanks, menos submarinos"
-vernon wasser-

88 sprint, 4dr sold
87 turbo 2dr, never ran
86 sprint, 2dr current DD!

I haven't done that on a MK1 carb but my '89 Mazda b2200 pickup has a carburetor and I think it came from the factory with an electric fuel pump in the tank, which is the first and only time I have ever seen a vehicle stock from the factory with an electric fuel pump and a carburetor. Anyhow, the in tank electric pump must have failed while some prior owner had it because when I bought it it had a generic cheapo parts store electric fuel pump spliced into the fuel line and fastened to the firewall with a bit of steel strap. Set up like that the truck had no end of fuel starvation and stalling problems ( like going uphill and fuel delivery cuts out and so on and so forth) so I ran rubber fuel hose bypassing the parts store electric pump and disconnected the electric wires to it and instead accquired and installed a mechanical fuel pump (there was a blanking plate of some sort covering the hole for the mechanical fuel pump in the cylinder head) and the truck has run like a top ever since, although so far that only means using it one or two or three days a year when I put a one day permit on it to haul stuff.

an electric fuel pump needs to always be mounted at the low point of the fuel supply line. they pump fine but not against an air bubble that forms in the line from the upper level of fuel in the tank to the mounting location of the pump on the firewall.

any electric fuel pump needs to be mounted at or near the lowest point of the fuel supply.

most of those low pressure in-line fuel pumps will run 15 to 20 psi while most carburetor float bowl inlet valves like between 8 and 12 psi fuel pressures. the flow rate is generally indicated by the cost of the pump and it's inlet and outlet diameters.

i'm not a mk1 enthusiast so my remarks are just general. i never take being corrected by the mk1 godz very hard because they know best.

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I have an electric fuel pump on my 1987 Sprint which has a rebuilt factory carburetor. No Problems....except I went through (3) fuel pumps before I got one that finally worked all the time (rebuilt ones from Advance Auto)....

Hooked it right up to the original hoses which is high above the gas tank of course, but no problems.

good topic....one I have thought of trying many times myself on my mk1....but to date have not. I just this past week also replaced a Manual pump that had gone bad after only 6 months. Warranty so stuck with the manual for now.

T3 is spot on with his comments about location. as close as possible to the tank is desired. They do not suck well over distance but rather are pusher pumps. After the failing of several mechanical pumps, in a very short time on my old 73 gmc I tried the electrical route. I also went through 3 electric pumps in under a year same problem. I Ultimately did find a pump that has now lasted over a year. The most reliable mounting location I found was within about 12" of the tank itself and low on the chassis. Up near the carb did not work at all.

In addition I would recommend a check valve on the discharge side. Non tank based electric pumps have a bad habit of leaking prime pressure when they sit for extended periods of time. This may or may not contribute to premature failure in some situations. Parts houses do not carry these but can be found on the net.

The one I have had the best luck with so far is the Mr Gasket, Low pressure unit, product #12S, 4-7 psi. As the MK1 carb does have a return leg off of the fuel inlet, I would tend to think these psi's would be fine. Most major parts houses do carry Mr. Gasket. The pump specifically says it is alcohol compatible.

To my research the leading manufacturer of fuel pumps in the US is a company called AIRTEX. Both myself and several others I know have had a lot of problems with AIRTEX Pumps, both mechanical and electric not lasting long. If I had to guess it probably has alot to do with alcohol in the fuels and internal rubber parts non being compatible. I find it real hard to believe that everyone needing a pump sees the same problem or AIRTEX would be out of business. I guess I have just been unfortunate. I have been through 5 Airtex pumps on 2 vehicles in the last year. I would avoid Airtex if possible. I spoke to my parts house (Advance) just yesterday on this topic and they now offer another line of Electric pumps, as well as the AIRTEX. Even they agree that they have had way too many returns on the line of product.

Let us know how the project goes....I might follow suit if you have success.

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Mike
Valley Grande, AL
1986 Sprint plus

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