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Thread: Won't Start-Fuel PSI drops to Zero with Key ON

  1. #1

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    Hi Everyone,

    I have put 135 miles of on the engine/atomic EFI/msd fuel system with no issues until this afternoon. I am running the Atomic with timing control and MSD fuel system PN2926, the car sputtered as I left my neighborhood then shut off and would not restart.

    Checked for spark and it was present, starter engages, however noticed my fuel pressure go up to 68 psi which is normal, then drop fairly quickly all the way down to zero with the key in the ON position. I already reset the atomic to defaults and re-entered the settings which I have been running successfully for many months. The fuel pump pressure still drops fairly quickly.

    My first guess if the fuel pump went bad (but in only 135 miles?). Or the atomic which controls the fuel pump may not be sending the correct signal to the fuel pump? My system is a very early Atomic and has the most current update. Can anyone help with this?

    Thank You


  2. #2
    Join Date
    Sep 2017

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    The fuel pressure dropping to zero a few seconds after turning the key on with the engine not running is not the reason your car stopped or will not start. When turning the key on, the fuel pump runs for a few seconds, but if it does not get the tach signal the pump turns off. Some people say the pressure drops slowly but my fuel pressure drops to zero pretty quick, this could be the check valve in the fuel pump, my car runs great so I am not concerned.

    You have not mentioned what your setup is, returnless, Atomic controlling ignition, FW versions, etc..

    But have you checked the screw has not loosened on the MSD adjustable rotor, if you have one? This is the most common cause for the splutter and stopping, I had the same thing.

    Let us know your setup and good luck..

  3. #3

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    I am running the following:

    -PWM with regulator (return fuel line)

    -Timing Control Enabled

    -All of the 9/25/14 released firmware

    -The adjustable rotor has loctite and is still in place.

  4. #4

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    Per a call into MSD, went through and rechecked everything like when the atomic was first installed, checked all parameters, rotor and #1 spark plug contact line up perfectly at 15 degrees BTDC. The Power module lights up, MSD box fires spark, the handheld screen lights up with no Error codes, and engine turns over but the car does not start.

    As mentioned earlier, on Sunday car drove out good then did misfiring sounds and then never started again.

  5. #5

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    If the fuel pressure comes up at key-on then drops off quickly, the check valve in the fuel pump may have gotten stuck open. This would allow the fuel pressure to bleed off quickly.

    This can lead to a hard starting issue. The fuel pump should come back on as the Atomic sees RPM at start up.

    With the system in PWM with Regulator mode, the fuel pressure will be significantly less at start-up/idle than it would be at cruise.

    Just to be sure that the check valve is the only thing we're dealing with here lets try something. Set the Fuel Pump type to Non-PWM with Regulator to see if the engine will start up easier.

  6. #6

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    MSD thank you for the input. I changed the setting to non-pwm with regulator and it did not start up.

    I will check the fuel pump check valve when I get home from work.

  7. #7

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    We do cover our products with a 1-year warranty from the date of purchase.
    Please contact our RMA department if you need to send the pump in for warranty. They can be contacted at 915-855-7123.

  8. #8

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    Hello MSD Tech, I replaced the Bosch fuel pump that I originally received with my fuel system PN2926, with the same model pump today. I noticed the replacement pump sounded healthier like my original pump when it was new, and also noticed that my fuel pressure is holding steady and not plummeting immediately like before.

    Are there any other checks or adjustments that you recommend I should do before attempting to start the car tomorrow?

  9. #9

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    Still trouble shooting my car that ran perfectly for months, then just stopped working. This evening I tried starting the car with the new fuel pump. Everything looks and sounds great on the fuel side with 64 psi now.

    The car will still not start, so I decided to pull the #1 wire from the spark plug and plug in an extra spark plug into the plug wire. I turned the key ON and could see the MSD 6A light turn on, but no spark while turning the engine over with the extra spark plug in place. Wouldn't a spark be visible on the electrode?

    At this time it looks like my Atomic EFI System had a fuel failure, which was fixed with a new fuel pump, but now I am dealing with what looks like lack of spark.

    Let me know if anyone can help troubleshoot this, thank you.

  10. #10

    Default Won't Start-Fuel PSI drops to Zero with Key ON

    I would check all your connections again. I had that problem at one time and that fixed it.

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