1966 Mustang: Mechanical To Electric Fuel Pump

Discussion in 'Classic Mustang Specific Tech' started by Alohastang, May 6, 2013.

  1. I converted from Mechanical to Electric Fuel Pump.... The Car Starts so much "faster" since the pump is actuated during Ignition "On" and the fuel is right there at the Carburetor !
    Electric Fuel Pump Mounting Plate.JPG Electric Fuel Pump Installed.JPG
  2. Great news & wld like to know some more details ?

    I have a 66 coupe and experienced continuos fuel related issues. It all started after i ran out of petrol one day. what followed ranged from vapor locks, no fuel reaching the carby, and continual stalling. Anyhow I spent unnecessary $$$ getting tank cleaned, carby redone, but the problems persisted. Then I was told the fuel pump was the cause because it was old and therefore was not sucking enough petrol. More $$$, . I replaced the fuel pump and my problem was fixed and i can now see petrol squirting out of both primary jets in the carby.

    However, now my new problem is the car runs very rich nothing has changed except for the new fuel pump?? I have also redone the mixtures several times. Another change i have noticed is there is now NO need to pump the accelerator at starting otherwise the car floods.

    Question.... Did you experience any similar fuel / carby problems since moving to an electric fuel pump?
  3. Sorry, my 66 coupe above is a stock factory 289 C4, A code , 4V mustang running a ford auto lite 4100 carby!
  4. YES !!! I had similar issues...... I hardly drive my Stang and the car was sitting for a few years and the Ethanol in the fuel these day's is what really screwed up my car; so I drained my tank and re-fueled with Ethanol-free gas and the car ran fine for awhile, but then my car stalled on the freeway and I thought I ran-out of gas, so I added more fuel and got the car started once again, but she died a 1/4 mile down the freeway and this continued as I "leap-frogged" down the freeway, until I just got the car towed home. Once home I checked the mechanical fuel pump and it was inconsistently providing fuel so I assumed something happened to the rubber diaphragm..... possibly caused by the Ethanol in the Fuel ---- this was why I decided to convert to a Electric Fuel Pump and I am glad I did !!!!! The car starts in one-try since the Electric Fuel Pump starts to run as soon as the ignition switch is turned "On" and the car Runs Great......

  5. Sounds like maybe to much pressure. I mech pump shouldn't have to much, but it might. You can put a regulator on it to lower the pressure, I'd start with a gauge they are cheap.
  6. Carburetors have A float bowl that always has a reservoir of gas... the engine isn't being fed by a steady stream from the fuel pump like Efi. But rather the pump fills up the reservoir which the carb runs off of.. if this pump magically made your car start better I'd check your float levels.. they may be set too low

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  7. Getting the fuel to my carburetor was the issue.... my mechanical pump was operating intermittently due to diaghram damage from the ethanol in the fuel after the car sat for a few years.
  8. How old was your old pump?
  9. My car was sitting for about 3 1/2 years..... the mechanical pump was about seven (7) years old. The rubber diaphragm in the pump was damaged from the ethanol in the fuel while sitting idle, which caused the pump to work inefficiently.
  10. Prob would of happened with non ethanol fuel. Anytime they sit and dry out like that it kills stuff like pumps and accelerator diaphrams.
  11. I added some Sta-bil (Fuel Stabilizer) in the tank prior to not-running the car, but I guess that didn't work.....


  12. Hi,
    What pressure you running at the carb. It's typical, you need a fuel pressure regulator. Most Eddy carbs don't lke more than 5.5 psi. Some Hollys will tolerate as much as 7 psi, depending on the build. They will run fine at 6, for most street rides and even some street strip rides.
  13. I am running a 600 cfm Holley (Vacuum Secondary's) Fuel Pressure is at 6 ~ 6 1/2 psi measured wih an in-line fuel pressure gauge at the carb....