Spark but no start

[hesermon]

I apologize in advance for being redundant in my posts, but for anyone offering suggestions that did not read my other post.... after a complete conversion from hot air to 87 setup, my fuel pump ran constantly with the key off. I think I'm reading a response correctly that the small black wire behind the alt. is only for diagnostic and should NOT be connected. I unhooked it and now the pump seems to run properly (only for a few seconds with the key on). Engine does not start. Replaced broken crank sensor, I DO have spark. Question, would a bad cam sensor prevent starting or only cause it to misfire and run like crap after it starts. It does not even try to start. Conversion included 87 harness, crank sensor, ECM 42.5 lb injectors and chip purchased for them. Only wires NOT connected at this time is the fore mentioned black wire and a three pin flat connector beside the alt. that almost looks like the cam sensor connector. There is also a green connector with two white wires that has a single flat spade type blade inside it that is also over by the alt. Next test (tomorrow) will be starting fluid but was hoping to avoid doing that. Any suggestions very much appreciated!

 

[86george]

I apologize in advance for being redundant in my posts, but for anyone offering suggestions that did not read my other post.... after a complete conversion from hot air to 87 setup, my fuel pump ran constantly with the key off. I think I'm reading a response correctly that the small black wire behind the alt. is only for diagnostic and should NOT be connected. I unhooked it and now the pump seems to run properly (only for a few seconds with the key on). Engine does not start. Replaced broken crank sensor, I DO have spark. Question, would a bad cam sensor prevent starting or only cause it to misfire and run like crap after it starts. It does not even try to start. Conversion included 87 harness, crank sensor, ECM 42.5 lb injectors and chip purchased for them. Only wires NOT connected at this time is the fore mentioned black wire and a three pin flat connector beside the alt. that almost looks like the cam sensor connector. There is also a green connector with two white wires that has a single flat spade type blade inside it that is also over by the alt. Next test (tomorrow) will be starting fluid but was hoping to avoid doing that. Any suggestions very much appreciated!

Yes a bad cam sensor will cause a no start.Take the cap off and see if it's broke.Get a noid light from a parts store to check for injector pulse.The green connecter flat spade wire is a tach hook up. The 3 pin flat wire sounds like it might be for the egr solenoid. Good luck

 

[whitehot1]

What do you mean by " replaced broken crank sensor" ?

Did it get broken from hitting the reluctor/timing ring on the balancer/hub?

If so was there any damage done to the reluctor/timing ring? did the ring get moved from hitting the crank sensor?

If the reluctor/timing ring is good did you set the new crank sensor properly?
with the required .025" air gap.

Did the engine ever run after the conversion?

 

[hesermon]

What do you mean by " replaced broken crank sensor" ?

Did it get broken from hitting the reluctor/timing ring on the balancer/hub?

If so was there any damage done to the reluctor/timing ring? did the ring get moved from hitting the crank sensor?

If the reluctor/timing ring is good did you set the new crank sensor properly?
with the required .025" air gap.

Did the engine ever run after the conversion?

The crank sensor was not tightened and the center part got broke off. There appears to be no damage to the ring.
I installed the sensor with the ring centered between the center and back lobe.

The engine has not started since the conversion. It turns over fine and has spark. Fuel system seems to be working fine. I have extra cam sensor, coil packs, and ign modules that I have not tried yet. All these on the car now is from the wrecked donor, I've never heard it run but obviously was when it hit the tree. Also, will the ECM from the 85 hook up just enough to start the car to eliminate this from the equation?

 

[whitehot1]

Here is a link to a good site for troubleshooting that may help.

Vortex Turbo Buick Performance

It sounds like you have the crank sensor installed ok,if you used the slot farthest from the connector plug end.

I'm not sure about your question on the 85 ecm.

 

[hesermon]

whitehot1, thanks for the link. I had spark (yellow) "suspect ECM or Cam sensor". I swapped out the cam sensor from my 85 and she fired on the first turn of the key. Now some tuning, a/c work and she is 95% done. (As we all know there is a large amount of stuff in that last 5 %)

 

[whitehot1]

Glad you got it running.

There is a ton of information on that site and hope it will help you in the future.

 

[Just a Six??]

Glad you got it running.

There is a ton of information on that site and hope it will help you in the future.

Agreed! Glad it's running & Steve's site is a valuable asset to us for these cars.