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Thread: Fuel pressure goes very low when car is hot.

  1. #1

    Default Fuel pressure goes very low when car is hot.

    Have an Atomic MSD working great. 1966 Toronado 425. I have a return line too. When the car is hot and I stop and turn off the engine of course the engine bay heats up.

    If hot enough then fuel pressure on a restart will will only go to about 7 PSI. Normally this is about 52 PSI. Letting the car cool for a few minutes and the pressure goes back up. I can hear the pump run but it stops after 2-3 seconds and pressure only reaches 7-10 psi. If I start the car with this low PSI it will eventually stall as the PSI is gradually decreasing.

    Is this a sensor problem of some sort? ECT is usually around 218°F and IAT might be 139°F with the outside temperature 100°F.

    Should I replace something? I'm afraid this will happen while driving. My system was purchased about two years ago, but only have 500 miles on it as the install was just finished.

  2. #2


    Are you using a return fuel system? When the car is hot and you turn on the key to the run position, dose the fuel pump turn on? Thank you.

  3. #3


    Hi,. Yes, I have a return fuel system. What I did was clean the throttle body with MAP spray and also cleaned the sensor. This solved the issue and the system was running great. However, today another problem has appeared, which I posted on a new thread.

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