Engine floods with too much fuel

Tiny
NOEL BEGLEY VANUATU
  • MEMBER
  • 2009 CHEVROLET AVEO
  • 1.4L
  • 4 CYL
  • 2WD
  • MANUAL
  • 85,000 MILES
When cranking it starts but lots of black smoke and it will get so much fuel that it stalls the motor. I have found another one that is running fine and checked the fuel pressure at the rail. They are both 55 lbs. Swapped the injectors, the coil and leads, the MAP sensor, throttle body with position sensor and idle up, crank sensor and cam sensor, ECU, EGR valve, fuel pump in the tank. Checked compression all around 250lbs. If I start the motor and remove the fuel pump relay and watching the fuel pressure it likes to run at below 40 lbs pressure and I just touch the relay on the contact to plug it in when it is about to stop allowing the pump to deliver fuel to 40 lbs. Then unplug it and I can keep it running fine. But the other one that is running fine is ok with the 55 or 60 lbs fuel pressure. I swapped the injectors a rail from the good going car into this one and it still over fueled. Have swapped every sensor even the oxygen sensor and removed the catalytic converter. Please suggest what I can try next.
Wednesday, December 22nd, 2021 AT 11:58 AM

5 Replies

Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
H,

The manufacturer's fuel pressure specifications are 55 to 62, so you are right where it needs to be. See pic 1 below.

Since you switched the injectors and it made no difference, I don't suspect any are leaking, so that leaves one other thing to check.

First, if you have a live data scanner, before starting the engine (cold) check the ECT (engine coolant temperature sensor) signal to the PCM. The information from the ECT is what the computer uses to determine the air-fuel mixture needed to run the engine.

Since these are electrical components, even if the ECT is totally wrong, the PCM doesn't know. All that is recognized is that it is getting a signal.

Here is what can happen. If the ambient temperature is 70 F and the ECT is indicating it is neg 40F, the computer will provide an extremely rich fuel mixture to allow the vehicle to run in the extreme cold.

Let me know if that is something you can check. Also, if you do have a live data scanner, let me know what the short-term fuel trims are.

Take care,

Joe

See pic below.
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Wednesday, December 22nd, 2021 AT 8:00 PM
Tiny
NOEL BEGLEY VANUATU
  • MEMBER
  • 17 POSTS
I have found the fault, I think. The pin that locates the cam gear has Shawn off and the gear has moved approximately two teeth. But when I took the timing belt off, I discovered that the lower gear has also been loose and the key in the pulley is worn enough to shift the timing about another 4 teeth. I have another lower gear and crank pulley coming tomorrow and have fitted a new pin to the camshaft and fitted the pulley back to the camshaft.
So hopefully this will solve the problems.
Thanks for all your help.
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Saturday, January 8th, 2022 AT 11:57 PM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
Hi,

Thanks for the update. Is everything working properly now?

Joe
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Sunday, January 9th, 2022 AT 5:21 PM
Tiny
NOEL BEGLEY VANUATU
  • MEMBER
  • 17 POSTS
Yes, it is running good now. I have some issues with the plugs on the injectors, but all is going well.
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Tuesday, January 11th, 2022 AT 1:17 AM
Tiny
JACOBANDNICKOLAS
  • MECHANIC
  • 110,176 POSTS
I'm glad to hear it and thanks for letting me know.

Please feel free to come back anytime in the future if you have questions. You are always welcome here.

Take care of yourself.

Joe
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Tuesday, January 11th, 2022 AT 7:08 PM

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