1990 Chevy Lumina 1990 Lumina 3.1 engine idles - no advance

Tiny
RESSHADEMECH
  • MEMBER
  • 1990 CHEVROLET LUMINA
Engine Performance problem
1990 Chevy Lumina Front Wheel Drive Automatic 71000 miles

Car idles great -push the gas pedal - chokes and dies
will restart and idle great - have had alot of work done to the car
Head Gaskets & Lifters and all associated gaskets
Vacume lines, Map sensor, Knock sensor, Idle air motor, Crankshaft sensor, Coils (3), Fuel pump and pressure regulator, Injectors good, Had Inition module tested - Good
This one has stumped me
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Monday, September 22nd, 2008 AT 11:01 PM

6 Replies

Tiny
RENAUDTN
  • MEMBER
Have you checked your fuel pressure, TPS sensor?
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Tuesday, September 23rd, 2008 AT 9:56 AM
Tiny
RESSHADEMECH
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New installed - could the ignition module play a role in this? Or computer? I am leaning this way
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Tuesday, September 23rd, 2008 AT 3:33 PM
Tiny
RENAUDTN
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I mean: have you connected a fuel pressure tester to check if your fuel pressure is good?
If low fuel pressure, test your fuel filter and make sure lines are not bent or something.

So you replaced the TPS sensor, correct?

Check your EGR and PCV valves.
Check your catalytic converter, or any restriction in the exhaust system.
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Wednesday, September 24th, 2008 AT 11:34 AM
Tiny
RESSHADEMECH
  • MEMBER
TPS? Sensor
Pressure 40 drops to 39 when throttle opened
makes it half open throttle then engine goes south and dies - New Fuel pump, filter and regulator
Leave the belt off and runs great - Stumped
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Sunday, September 28th, 2008 AT 9:55 PM
Tiny
RESSHADEMECH
  • MEMBER
TPS new - I thought malfunction until I left belt off runs great full range throttle, engine strong and reacts like a new car - still stumped
Cat year old - exhaust strong and lean no fuel smell

Took wire harness apart to computer and re-loomed
from injectors, Crank sensor, ingnition module
still have problem - replaced alt - questioned regulator - still have problem

this car only has 70,000 miles and alot of money invested
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Sunday, September 28th, 2008 AT 10:06 PM
Tiny
RENAUDTN
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Okay, you would probably have to confirm with the specific service manual, but I believe the fuel pressure on this car is supposed to be between 41 and 47 psi.
If you get 39-40, it may not be enough when the engine is under higher load.
If you replaced the fuel pump, filter, pressure regulator, I would then check the voltage at the fuel pump and make sure the fuel lines are not obstructed, or the fuel pump inlet sock is not clogged. Low voltage would indicate something wrong in the wiring, like high resistance.

Here is a little test you can do to help you determine if your pump is pumping enough fuel in the system:
With engine idling, pinch shut the return line. You should read about twice as much fuel pressure than usual.
If the pressure doesn't go up with return line shut, that would mean your pump cannot deliver enough fuel at higher speed. Check for possible causes mentioned above.

In case I'm wrong with the fuel pressure, here are a few more possibilities:

-I forgot to ask, but have you looked for codes?

-Check your EGR valve.

-How is your air filter? If it's badly clogged, it could be your problem.

-I know you said you replaced some vacuum lines, but have you replaced the vacuum lines going to the MAP sensor? Sometime they can collapse under vacuum which messes up the MAP sensor inputs to the PCM. Even if they " look' good, they may need to be replaced if you haven't done it yet.

-Have you checked your spark plugs and wires? You need a strong spark to run the engine smoothly under high load.

-If all of the above are OK, you may want to have your pcm tested.
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Monday, September 29th, 2008 AT 3:21 PM

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