I just got a 88 firebird with the 305 tpi engine. sometimes when i go to start it the fuel pump will run briefly to charge the rail and shut off. I then start it and it starts right up and runs perfectly. I then drive it for ten minutes and shut it off. I then go to start it again and the fuel pump continues to run and will not turn off. When the pump is running the car will not start. I checked the pressure on the rail and it immediately pressureizes to 42 PSI within a couple of seconds. Why does the pump continue to run and why won't the car start if the pump is running? It appears as if when the pump continious to run then the computer will not fire the injectors. I don't know much about these engines, but it is the strangest dam thing i ever ran across. If the pump shuts off within a few seconds the car fires right up and runs fine. No codes. If it does not and you manage to get it started it runs like **** and serveral codes appear. Is there some sensor that tells the computer that the fuel rail is fully pressurized and that it is OK to start or what. I don't understand what is going on here, but its definitely related to the fuel pump running sometimes forever. Anyone ever have any simular problem?

 

that is strange. im kind of leaning toward the ecm at this point.
but, we need more info, when it kicks codes, what are they?
any lights coming on in the dash? what about your check engine light, does it work normaly? do you have a scanner you can hook up to it?

 

The check engine light does work properly. I get the codes from jumpering A and B in the test connector. No other lights come on on the dash except for the ckeck engine when it kicks codes. The thing is is the pump shuts off briefly after the ignition switch is turned on the check engine light does not comes on and when you check the only code is 12 saying all OK. Tonight after work the pump shut off about 5 seconds after the ignition switch was first turned on. The car fired up immediately. I drove it around hard for about 30 minutes or so. No check engine light and ran like a top. I then shut it off and and turned it back on again. The fuel pump did not run and car fired right back up again and no codes when ckecked again.. About twenty minutes later I tried to start again and would only try to start briefly. Listened and the pump was running again. I ckecked and only got code 42. I played with it for the next hour, but the pump will not shut of by itself and therefore the car will not start correctly. The only way to shut off the pump is to pull the connector used to reset the computer or unplug the fuel pump relay. At least I think its the fuel pump relay. Its located on the firewall on the driver side. There is three relays and some flat module . Two relays have bellow or pillow type connectors. The one I think is the fuel pump does not. It has five wires 1 big orange, a smaller orange, a green/wht, blk/wht and 1 big tan/black mounted on rubber mount.

 

If i get the car started and drive it running very badly wanted to stall out and bucking and jerking, and then check codes afterwards I get the 42, 33, 34 and 54. I don't think these codes are real though beacause I am driving the car running poorly.I just went down again to try it. The fuel pump did not turn on at all now. It started right up but then stalled. I was not touching the gas pedal. I tryed it again. Again pump did not run and it fired right up and was OK but did throw code 42. It seems to be OK though. After a bit of idleing it idled down to 750 RPM's and sounded fine. It appears as if something is heating up and failing. Once it is in fail mode it will not shut off the fuel pump and allow the car to start. There has to be something that tells the computer when the fuel rail is charged and its Ok to start. From what I understand the car has had this problem for many years. It has been to three different dealers and many sensors have been changed. The fuel pump and filter was even changed. The dealers always want to change the MAF sensor but if this was bad would the car ever run right at any time. I wouldn't think so. I mean honestly the car runs perfectly when is starts correctly.

 

It might be the fuel pump relay dying. As you know, it's supposed to just prime the pump for 2 seconds, then shut off. But, once it gets hot enough, it may not switch the fuel pump off when it's supposed to. It's cheap enough to buy a new one and swap it, just to see.

Sounds like the other problems are related to it being so loaded up with fuel when it doesn't start right away. Once the excess fuel clears out of the chamber it'll idle normally, but I'd bet the plugs are starting to foul also.

 

I just got done changing all three relays with new ones. Fuel pump, MAF burnoff and the other one which I am unsure what is called. No change. Started up and ran fine. Drove for twenty minutes . Let sit for five. Turn on and fuel pump won't shut off. Tonight i pinched shut the fuel return line and fuel pressure shot right up. I pinched of the supply line and fuel pressure on rail dropped. I applied vacuum to the FPR and the rate of fuel through it changed. I also comfirmed that If the pump does not shut off then the injectors do not fire. There is no problem with fuel pressure on the rail the question is why don't the pump shut off after the two seconds once it has run. It appears to be heat or coolent temperature related. I left the ignition on and therefore pump running for about 45 minutes and then it finally clicked off. The car started right up and no code so it appears like when the coolent temperature dropped the pump shut off. I may be way off base but this is driving me nuts. What should be normal operating temperature. Mine takes forever to get to 160 degrees but it seems like the pump will shut off if below 140 degrees. Does coolent temp have anything to do with it? Someone has to know what causes the pump not to shut off after the two seconds before ignition. GM doesn't although!

 

I just got this problem resolved. It turned out to be the ECM.