98 Lumina LTZ Idol problem

[LTZluminaguy]

My 98 Lumina LTZ 3.8 liter will only start after pumping the gas pedal and holding my foot on it, if I take it off it will die. Before this started it was becoming difficult to start I would have to pump the gas pedal to get it started , but once it started it ran ok. I also would sometimes for awhile now get a strong smell of gas after shutting off my car or sometime while sitting still and idiling. I did a fuel pressure check and got 52 psi the correct range is 48 to 55 psi, since the fuel pressure appears ok and I could hear the fuel pump running I am assuming it is ok and the fuel filter is alright. Could my problem be the fuel pressure regulator, even through the fuel pressure test was good? I pulled the vacuum line of the fuel pressure regulator and no gas came out and there appears to be good vacuum on the line. I check it while the car was running with someone holding their foot on the gas pedal. I have 83,000 on it and the car is a one owner with the only problem being a slight oil leak on back side of engine, which I haven't fix since the shop wanted over $400.00 to fix, I can by a lot of oil for that amount. I am on a budget so I would like to fix this myself if I can, the car is in great shape.

[Schurkey]

Originally Posted by LTZluminaguy

My 98 Lumina LTZ 3.8 liter will only start after pumping the gas pedal and holding my foot on it, if I take it off it will die. Before this started it was becoming difficult to start I would have to pump the gas pedal to get it started , but once it started it ran ok. I also would sometimes for awhile now get a strong smell of gas after shutting off my car or sometime while sitting still and idiling. I did a fuel pressure check and got 52 psi the correct range is 48 to 55 psi, since the fuel pressure appears ok and I could hear the fuel pump running I am assuming it is ok and the fuel filter is alright. Could my problem be the fuel pressure regulator, even through the fuel pressure test was good? I pulled the vacuum line of the fuel pressure regulator and no gas came out and there appears to be good vacuum on the line. I check it while the car was running with someone holding their foot on the gas pedal. I have 83,000 on it and the car is a one owner with the only problem being a slight oil leak on back side of engine, which I haven't fix since the shop wanted over $400.00 to fix, I can by a lot of oil for that amount. I am on a budget so I would like to fix this myself if I can, the car is in great shape.

Does the TPS, MAP, and coolant temperature sensor read within normal ranges? Any codes stored?

[LTZluminaguy]

What is TSP and MAP? My problem is when the engine is cold and has not been running and the service engine soon light does not light up, there is no kind of light of signal that anything is wrong. Also when doing the fuel pressure test not only did it show 52 psi droping slowly to 48 psi but it drop to 42 psi when I started it, (holding my foot on the gas pedal) which is what it should do according to Haynes manual for Luminas. While doing this it smoked some out the exhaust too.

[Schurkey]

Originally Posted by LTZluminaguy

What is TSP and MAP? My problem is when the engine is cold and has not been running and the service engine soon light does not light up, there is no kind of light of signal that anything is wrong. Also when doing the fuel pressure test not only did it show 52 psi droping slowly to 48 psi but it drop to 42 psi when I started it, (holding my foot on the gas pedal) which is what it should do according to Haynes manual for Luminas. While doing this it smoked some out the exhaust too.

TPS = Throttle Position Sensor
MAP = Manifold Absolute Pressure sensor

Unless you can read the sensor information with a scan tool, you're going to have a tough time diagnosing the problem.

Does the fuel pump run for two seconds when you first turn the key to "Ignition" and the engine is NOT running? Do you have fuel pressure then?

[LTZluminaguy]

Yes the fuel pump does come on and run as soon as you turn the key, as I said earlier there is good fuel pressure. Since the Service Engine Soon light is not staying on, would there be anything showing up with a scan tool, I throught that light would have to stay on for there to be anything showing up on computer/scan tool.

[Schurkey]

Originally Posted by LTZluminaguy

Yes the fuel pump does come on and run as soon as you turn the key, as I said earlier there is good fuel pressure. Since the Service Engine Soon light is not staying on, would there be anything showing up with a scan tool, I throught that light would have to stay on for there to be anything showing up on computer/scan tool.

Unlike a cheap 'n' crappy code reader, a scan tool will show all the activity on all the sensors, pending codes that haven't actually turned on the SES light, etc.

Having fuel pressure at idle or key-on, engine off does not guarantee that you don't have a defective check valve or appropriate volume from the pump.

[jeffcoslacker]

With the engine idling read fuel pressure at the rail.

Clamp the return line shut. Reading should jump a bit then settle back to norm. If it shoots way up and stays up, new FPR time...

Sure sounds like it's overfueling. Your fuel smell when sitting is from overpressure in the rail leaking through the injectors while they bleed off the excess pressure. Then when you try to start, you've got fuel soaked cylinders.

Crank the motor briefly in the morning without starting, pull a plug out...bet it's soaked.