Any ideas on a no start condition??

[Dreamcar86]

Normally I figure this stuff out but this one has me stumped. This is a no spark situation however every so many cranks it will spark then nothing again. Has anyone had this no spark then spark then back to no spark? Is there a ground wire I am missing or wiring harness problem?

Here is what I have done so far:
- checked all fuses
- checked battery voltage while cranking
- swapped out my coil and ignition module with a new one I had on the shelf
- swapped out my crank sensor with one I had sitting on the shelf.
- checked fuel pressure
- visually inspected grounds
- checked all connections and pins

What next?

 

[earlbrown]

Have you lost a timing set? What did it do the last time it ran?

 

[SHADOWII]

Have you checked the fuseable links? Maybe the org. wire?

 

[Dreamcar86]

Have you lost a timing set? What did it do the last time it ran?

This is a new motor with about 500 miles on it. The thing has run like a champ since the first crank. I had turned it on pulled it out of the garage, turned it off came back out 15 minutes later and no start. My gut reaction was a crank sensor.

 

["Reaper"]

Could be cam sensor cap or cam sensor window. ( metal piece under cap)

 

[Dreamcar86]

Have you checked the fuseable links? Maybe the org. wire?

Yes, checked fuse box, all connections to include checking for bent or broken pins.

 

[Dreamcar86]

Could be cam sensor cap or cam sensor window. ( metal piece under cap)

Would that create a no spark situation or intermittent spark?

 

[GNVenom]

Ignition switch.

 

[Dreamcar86]

Ignition switch.

Hmm, anyway to test the switch?

 

[GNVenom]

Replace it is about the best way. If the new switch works, you have effectively tested it.

All joking aside, I do see the ignition switches fail more these days. the age has caught up with them. Inexpensive part to have in your arsenal.

 

[Dreamcar86]

Replace it is about the best way. If the new switch works, you have effectively tested it.

All joking aside, I do see the ignition switches fail more these days. the age has caught up with them. Inexpensive part to have in your arsenal.

Very good point after 27 years of cranking this car over I would be tired too. Thanks for the heads up I will give it a try!

 

[TurboTdr3.8]

ECM is coming and going

 

[Dreamcar86]

ECM is coming and going

I have considered this. Guess I'll start with the ignition switch then if that does not work move to the ECM.

 

[TurboBob]

you said it starts on some attempts. when it does, shake and rattle all of the electronics you can get to. The harness and connector components age along with the rest of the parts.

a loose cam sensor can act like this, take the top off it and make sure the tang that holds the interrupter is not broken and moving around.

does it start more easily if you press the gas slightly?

B

 

[Dreamcar86]

you said it starts on some attempts. when it does, shake and rattle all of the electronics you can get to. The harness and connector components age along with the rest of the parts.

a loose cam sensor can act like this, take the top off it and make sure the tang that holds the interrupter is not broken and moving around.

does it start more easily if you press the gas slightly?

B

I have rattled the harness a time or two which makes me wonder if that was helping. Before the engine went back into the car I installed RJC's cam sensor fix however it never hurts to look again. Have not given it throttle yet.
Thank you for your input!

 

[Bescurred]

How's your harmonic balancer look? Mine did something awfully similar and come to find out I had a crack in the balancer that would cause the car to crank and crank and crank then eventually start.

I was thinking crank sensor too...

 

[HouTX87]

I thought the cam sensor controlled injector timing, not spark.

 

[GNVenom]

Cam sensor sets fuel timing, not spark timing. But, if there is no cam sensor signal on startup, there will be no spark. Ever.

 

[Dreamcar86]

How's your harmonic balancer look? Mine did something awfully similar and come to find out I had a crack in the balancer that would cause the car to crank and crank and crank then eventually start.

I was thinking crank sensor too...

I will also look at the harmonic balancer. Just had it machined for the new motor and it might have cracked during the process. One more thing to look at.
Thank you for the input!

 

[Dreamcar86]

Cam sensor sets fuel timing, not spark timing. But, if there is no cam sensor signal on startup, there will be no spark. Ever.

Could be cam sensor cap or cam sensor window. ( metal piece under cap)

I thought the cam sensor controlled injector timing, not spark.

Well I feel silly. For those above who said cam sensor you are correct. The first time I checked I had only made a visual inspection however on the second look I physically twisted the interrupter ring and it was able to wiggle back and forth about 1/16 - 1/8". Apparently when I did the RJC cam sensor fix I did not tighten the hex head bolt tight enough and there was just enough play to disrupt the signal. Its always the little things.

Thank you all for giving me a fresh perspective on this!