1990 Chevy Lumina Hart to start cold or hot

Tiny
GOLFNGUITARS
  • MEMBER
  • 1990 CHEVROLET LUMINA
  • 6 CYL
  • FWD
  • AUTOMATIC
  • 220,000 MILES
Just had a new pipe and muffler installed. I have been having trouble starting the car since that day. Perhaps just a coincidence, but it's puzzleing. Car runs awesome. Lots of power. Idles fairly smooth. Within the last 2 years, new fuel pump, crankshaft sensor, plugs, wires, fuel filter, airfilter, AIC motor, PCV valve and ECC. Tough to start weather it's cold or hot, I have to make several attempts before it starts, then it starts but not smoothly for a second or two, then it's fine. I thought it could be the fuel pressure regulator. I disconnected the vacuum hose, no fuel odor or leaks. I have no way of doing a pressure test myself. My old exhaust system had many leaks, and the car ran fantastic. With the new exhaust, the car runs good, but a little slower when accelerating fast, but there are no issues with power or acceleration. The car never stalls. Doesn't burn oil. However the exhaust odor is a little strong. Someone mentioned to me it smells like a rich mixture. Bad O2 sensor? Bad fuel regulator or leaking injectors? Could the new exhaust have anything to do with the problem? I have noticed when it does start, if I shut it off for a minuite or two, it will restart just fine. I love this car, and will never get rid of it. I want to keep it running forever.
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Saturday, July 24th, 2010 AT 10:01 PM

3 Replies

Tiny
RASMATAZ
  • MEMBER
Hi golfnguitars, Welcome to 2carpros and TY for the donation.

Its a must that you use a fuel pressure tester to check the fuel pressure if its within specifications. If okay test the coolant temperature sensor, clean out the idle air control valve and test the throttle position sensor. Could very well be the ignition switch
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Sunday, July 25th, 2010 AT 2:34 AM
Tiny
GOLFNGUITARS
  • MEMBER
I tested the fuel pump by connecting 12 volts to the test connector, all is well there. I tested the fuel pressure, connected the gauge to the schrader valve, the pressure is low when the key is in the ON position, 10psi. After I started the car, pressure is within specs, 32psi. From there everything is normal. Tapped the throttle, pressure jumped about 5psi, disconected the vacuum from the regulator, pressure jumped 10psi. No fuel dripping out of the vacuum line, no odor. I did change the ECT sensor, no effect on the starting issue, however I believe the air/fuel mix is better. Again, once the car starts, it is fine. If this matters, there is just a slight hesitation when I tap the throttle gently. Very slight!
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Thursday, July 29th, 2010 AT 5:44 PM
Tiny
RASMATAZ
  • MEMBER
Check and test the throttle position and manifold absolute pressure sensors
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Thursday, July 29th, 2010 AT 5:47 PM

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