Fuel pump quirks

[Jon Klein]

hi guys...I have a 93 ATX and I have a fuel problem (I think). I got my fuel pump replaced at 122k along with the 60k service...and they said that they hooked the car's fuel line up to a machine and ran it on some kind of fuel system cleaner. After that the car never started right again, and they said it would go away eventually. So heres the problem...when the car is cold it will just crank for about 10 seconds or more, unless you put you foot on the gas it will take only 5 seconds. If you turn the key to ON, and let the fuel pump run, and keep turning it off and on for about 3 times, you will hear the pumps winding get slower and lower pitched, then it will start right up. When the car is warm, usually no matter what it will start on a dime. sorry its so long.....please help me....

JON

 

[89 black SHO mtx]

any codes??? sounds like it might be a temp sensor but could be a bad check valve in the pump letting it bleed down. check your fuel pressure 1 morning before you start it attach a gauge to the schrader valve and turn the switch to run (don't start it) it should be close to 40 psi with the 2 second burst if not you could have an injector sticking causing it leak down or some other problem

 

[sdpatt]

Sounds like the discharge check valve in the fuel pump or the pressure regulator on the fuel rails is not holding the fuel pressure in the line to the engine. The change in the pump sound during the repeated key-ons indicates that the pressure is increasing each subsequent turn of the ignition key. Being a positive displacement pump, the fuel pump will spin faster when the outlet pressure is lower and spin slower when the pressure is high. It should take only a split second to fully pressurize the fuel lines on the first pump start.

 

[aaronsbiza]

I have the same exact problem and symptoms on my 95ATX, and after a bit of research on the forum along with a post very similar to yours I have singled it out to the fuel pump.