86 Vette not running

[metoo1012]

Drained fuel system, checked for contamimantion, none found. Added fresh fuel and the same results. Runs for 3 seconds and then dies. Will not start everytime, just when it wants to.

 

[milehigreg]

Don't Give Up!

About 2 years ago, my 89 exhibited the exact same behavior. I used the FSM to troubleshoot but it didn't provide any definite answers for this issue nor did I fix the problem.

I read that you have replaced the injectors. Injectors were the eventual source of my problem. The original injectors apparently do not tolerate ethanol very well and the insulation on the coil degrades and causes a short. This reduces the resistance of the coil and too much current flows. The ECU detects this and shuts down the engine. Two ways to test this. Check the resistance of each one. Second, disconnect the injector plugs one at a time and try to start the engine. The L98 is batch fired which means that all the injectors on either side of the engine fire at once. If you isolated the bad injector by disconnecting it, the overcurrent situation won't occur and the ECU won't shut down the car. Maybe you got a bad new injector. If this doesn't work, I suggest checking the injector clips and wires for a short. The FSM says absolutely nothing about this malfunction!

GMjunkie usually chips in on these situations and suggests the EGR is being held open by a chunk of carbon. You mentioned checking this but didn't say whether you did or not.

When I finally changed the injectors on mine, I went ahead and replaced the EGR and the FPR since they are both located under the plenum and runners.

Good Luck and keep after it! It took me three months and replacement of the ECU, ignition module, complete removal of the dash to check the VATS module, checkout of the MAF andTPS, replacement of the fuel pump and then finally replacement of the injectors, EGR, FPR and the ignition connector harness. She runs like a top now and I know those items won't cause me any issues.

 

[metoo1012]

What do you mean by the ignition connector harness? Is this the short one behind the distrib?

 

[metoo1012]

Thanks for the link, great information.

 

[metoo1012]

UPDATE AS OF 5/06/2006 Starts and runs for maybe 3 seconds and dies, noid light flashes and timing light flashes as the motor dies.Continuing to crank while it dies. lights flash.

latest testing new injectors ohmed out at 14
replaced ignition control module with oem
had alternator checked - passed, wires passed
replaced battery cables (desperate try)
Battery tested and charged
Replaced gaskets on plenum and tubes, had to check not sure if they were damaged.
Tried another ecm and memcal, same results.
rechecked egr valve, no problem
hot wired from dist. 4 wire to ecm bypassing all connectors

going crazy. priceless

 

[milehigreg]

Feelin' Your Pain

I printed out the L98 start sequence info when I was working on mine. It doesn't say a thing about the injector issue. When you run out of possibilities from the start sequence, try the disconnecting individual injectors test and see if she starts and runs. Then I would check the connectors and then the wires for shorts.

Victory will be sweet when you figure this out!

 

[milehigreg]

Any Progress?

Any news? Did you figure it out? Did you check the resistance of the cold start injector? Did you check the injector wiring harness? If you figured it out, let us know.

 

[632bb]

UPDATE AS OF 5/06/2006 Starts and runs for maybe 3 seconds and dies, noid light flashes and timing light flashes as the motor dies.Continuing to crank while it dies. lights flash.

latest testing new injectors ohmed out at 14
replaced ignition control module with oem
had alternator checked - passed, wires passed
replaced battery cables (desperate try)
Battery tested and charged
Replaced gaskets on plenum and tubes, had to check not sure if they were damaged.
Tried another ecm and memcal, same results.
rechecked egr valve, no problem
hot wired from dist. 4 wire to ecm bypassing all connectors

going crazy. priceless

I keep reading this and can't figure out why this don't run.. So. I have only one reason that it won't run, You have a BAD TIMING CHAIN, Its the only thing that would do what it is doing assuming all the other parts replaced are good. I would pull the cover and check it out.

 

[metoo1012]

You are 100 per cent correct. Timing chain was defective due to plastic gear on the cam shaft. I found this by watching the rotor jumping while it was rotating, mystery solved. For me this has been a trial on my patience, mechanical and electrical skills. Not to mention one of the strangest problems I have ever come accross.

Thank you all for your imput and encourgement especially Ron Kane from Ind.and Jon from Georgia.

I had to hear it running before I could post the final results.

 

[milehigreg]

YEEEHAAAAA!!!!

Congratulations! Thanks for sharing the final solution. It may have been a trial on your patience but your patience paid off. You now have a running torque monster L98. You've learned tons about its operation and you've checked or replaced a lot of stuff that should now not give you any problems. You've also probably helped someone else now or in the furture by sharing the experience. Enjoy your FORMER basket case!

 

[roger longman]

Hi 632bb, WELL DONE! Roger.