Installing an Electric Fuel Pump in a 1973 Mustang

A friend has a 1973 Mustang Grande that someone swapped in a 1985 5.2 liter engine, and Automatic OverDrive (AOD) transmission into. What a mess this is going to be, given the radical changes with 1985 Mustangs compared to early generation Mustangs. One of the differences is in 1973 the engine had a mechanical fuel pump, but in 1985 Mustangs had an electric fuel pump.
Currently the 1973 Grande has no fuel pump. So I put together some parts and did some pre-assembly of the parts needed for this project. In a few days I am going to ship the parts to Poland so the owner of the Mustang can install the fuel pump.
There is more to this project than meets the eye.

[@Kn240sx]

Thank you! Great explanation as usual. Been thinking of adding an electric pump to my '73 hoping to help cold starts after not using car for few weeks.

[@gilberthale7777]

I am assuming your engine is not stock. Are you running a carburetor? If so, which carb? The reason I ask is some carburetors have a Power Valve, where a leaking or ruptured diaphragm can allow raw fuel to leak into the intake manifold, not just when the engine is running where intake manifold vacuum can suck down huge amount of raw gasoline. rather, the fuel in the fuel bowl can end up slowly leaking into the intake manifold, which causes washdown of oil in affected culinders, and hard start due to an empty fuel bowl.
Just a fe2 thoughts I conjured up re: the hard start when cold situation.

[@Kn240sx]

@@gilberthale7777 Its a 4160 with vac sec and electric choke (p/n 0-80457S). It's about 20 years old. First start after winter storage takes about a minute of cranking. Changed plugs this year and they were pretty sooty for only about 500 miles of use. I've been working my way through your videos to fix up the electrical and vacuum issues, but carb tuning has me baffled.

[@gilberthale7777]

@@Kn240sx It is sounding like you have a leaking or ruptured Power Valve. By draining the fuel bowl after sitting unused, when you later try to start the engine there is no fuel in the furl bowl to squirt fuel out the accelerator pump when starting it cold. It would take some bit of cranking to refill the fuel bowl. Once it fires up the leaking Power Valve will cuse the carburetor to run very rich, and can definitely foul spark plugs. One way to test to see it the Power Valve is leaking is to warm the engine up, then turn the idle mixture screws to the far right to close off fuel flow via the idle circuit. If the engine is still idling it is a sure sign the fuel is coming from "somewhere.? Most likely the Power Valve.
But wait, there's more. One reason these Power Valves will rupture is when the engine has a backfire, or even a burp back event. That puts positive pressure into the intake manifold, and that pressure is sent to the Power Valve's vacuuum chamber where the valve's diaphragm is not designed to handle such a reversal of pressure from one extreme to another. Holley, in 1992, introduced a Power Valve Protection circuit, where they use a spring loaded check ball in the Power Valve channel in the base plate to block of positive pressure, thus keeping the diaphragm from being subjected to blowback pressure. Holley actually makes a kit for pre-1992 carburetors to add the Power Valve Protection components for those older carburetors. The site for that kit is below
www.holley.com/products/tools/carburetor_tools/parts/25-100QFT
For folks not believing the Power Valve blowout is a real thing, here are some interesting article...
www.google.com/search?q=holley+carb+power+valve+blowout+protection&rlz=1C6CHFA_enUS1044US1046&sca_esv=5ac3b5860f52b755&sca_upv=1&sxsrf=ADLYWIK9zwUATkOiBQYj_yU2FgLUVwoeRg%3A1717790082817&source=hp&ei=gmVjZsSzL8eI0PEP2N-D0Ak&iflsig=AL9hbdgAAAAAZmNzkhDeHE5xnCPtK8yMKtfgtYjecLe9&oq=holley+power+valve+protection&gs_lp=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&sclient=gws-wiz
www.enginebuildermag.com/2013/01/the-truth-about-power-valves-used-with-holley-carburetors/

[@gilberthale7777]

@@Kn240sx I would check to see if the carb has the Power Valve Protection circuit. This could be your entire problem.

[@Kn240sx]

@@gilberthale7777 Engine definitely stalls when I turn either idle screw in past 1-1/2 turns. Best idle is at 2-1/2 turns open. Carb is from 2003, so I assume it has the protection circuit but I’ll check. Just for reference, the engine is basically stock with all emission stuff removed. I did change the cam out 40 years ago to 272/284 duration, 484/512 lift. Manifold is some kind of Edlebrock (SP2P I think) which is mostly for low end torque. Probably not a good combination of parts, but I was in high school and didn’t know better! Also have headers and Pertronix 2. Thanks for your help!! Your videos have helped me much more than the forums!