1996 Tahoe 5.7 cranks but wont start

Tiny
BRICEH
  • MEMBER
  • 1996 CHEVROLET TAHOE
  • V8
  • 4WD
  • AUTOMATIC
Changed rod and main bearings in a '96 tahoe put it all back together and started it up.
it ran for about 15 seconds and I had gotten oil pressure. It died suddenly so it made me think something electrical. The engine wouldnt refire it would just backfire out the exhaust occasionaly. I tested for spark and I have spark. Im getting fuel u can smell it out the exhaust and the plugs were wet with fuel. I checked all the fuses and they all tested good. Im not sure what to try next. If u have any suggestions they would be greatly apprieciated.
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Monday, November 22nd, 2010 AT 8:28 PM

2 Replies

Tiny
WRENCHTECH
  • EXPERT
Check the compression on all cylinders. Sounds like you may have a timing issue or you could have the distributor out of synch. The ignition timing is not adjustable.
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Monday, November 22nd, 2010 AT 8:34 PM
Tiny
DRCRANKNWRENCH
  • EXPERT
Sounds like it may be getting too much fuel. You might want to run a compression test as well to make sure that everything is ok and the rings are sealing because that will cause the air/fuel charge to not ignite and the engine won't run.
If the truck sat for a while without running, the injectors coulod be part of the problem as well. They can clog from olod gas congealing in them or they can fail elecrtically where the solenoid sticks open, ususallyclosed, either wilkl casue problems.
There are also 2 items that act as a choke and a load detector. The Fast Idle and/ or the Idle Air Control Valve work as a choke to get the motor going and to sense increses in engine load to which the computer reacts and idles up or richens the motor to keep running.
If the plugs are sparking, the fact that they are wet with gas leads me to think that there may be an issue with timing such as the chain being off a tooth or 2 whcih could have caught a vavle or is making compression of the charge impossible and the gas is just getting pumped through.
Also, the O2 sensor could be bad and sending the ECU a signal to dump gas.
Electrical stuf is hard to track especially in a sistuation where the vehicle has sat or has a new engine.
Start with mechanical eorro with a compression test and then double check TDC by remeoving the vavle cover over cylnder number 1 and make sure it is timed correctly with the cam.
Let me know how it goes and I will keep an eye on this post and get back ASAP.
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Monday, November 22nd, 2010 AT 8:47 PM

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