Strange Issue

**Resin** · 4 Weeks Ago

I've got a weird one if you want to scratch your brain.
For all intents and purposes, I am working with an L03 89 Firebird. It's actually closer to an L05 now but that's beside the point.
I got it to start a couple of times, it was running super rough though. Timing was jumping around.
Then it quit sparking.

What I can't wrap my head around, is that the coil is sending power to the middle post of the distributor.
The injectors are firing.
But there is no spark at the plugs.
Where is the power from the coil going?

Plug wires are brand new all within ohm spec. 1.3k for the wire going to #1.
There is nothing flowing to the plug though.

I've seen plenty of other posts about similar issues, but they all don't have an injector pulse and/or no spark at the coil either.
Has anyone seen anything like this before?
Could it be an issue with the ECU?

Regards,
Resin

**Sledhead2** · 4 Weeks Ago

If it is coming out of coil wire then look at your cap and rotor. spark should go right from rotor tap to cap post.

Look for carbon marks in the cap, they will look like little stress cracks.

Did button burn out on rotor.

**Resin** · 4 Weeks Ago

I will take a close look at both of them later today. I have tried two entirely separate distributors and they both behave the same way. I have tried two separate coils as well. Thanks for the suggestion though, it's entirely possible they are both bad. I will report back.

Regards,
Resin

**Resin** · 4 Weeks Ago

Well, I took a look at both of the distributors and I don't see any damage anywhere. Things have now gotten weirder though.
Now I can't get the car to crank. Fuses are all good from what I can tell. Lights on the dash come on with the key. I get 12v to the injectors.
The security light now stays on. I've tested the resistance of the key and it is still in spec. I tested the continuity of the wires to the ECU and they're not broken with 0 ohms. Tested the key side of the circuit too. I'm starting to think more and more that my ECU is dead. Does that track? Am I crazy?

**Fast355** · 4 Weeks Ago

Originally Posted by Resin

I've got a weird one if you want to scratch your brain.
For all intents and purposes, I am working with an L03 89 Firebird. It's actually closer to an L05 now but that's beside the point.
I got it to start a couple of times, it was running super rough though. Timing was jumping around.
Then it quit sparking.

What I can't wrap my head around, is that the coil is sending power to the middle post of the distributor.
The injectors are firing.
But there is no spark at the plugs.
Where is the power from the coil going?

Plug wires are brand new all within ohm spec. 1.3k for the wire going to #1.
There is nothing flowing to the plug though.

I've seen plenty of other posts about similar issues, but they all don't have an injector pulse and/or no spark at the coil either.
Has anyone seen anything like this before?
Could it be an issue with the ECU?

Regards,
Resin

How can it be closer to a L05? It either has a 305 or a 350.

That being said, cap and rotor, especially the rotor ar suspects. If the rotor has burned through, the spark is grounding out on the distributor shaft.

**Fast355** · 4 Weeks Ago

Originally Posted by Resin

Well, I took a look at both of the distributors and I don't see any damage anywhere. Things have now gotten weirder though.
Now I can't get the car to crank. Fuses are all good from what I can tell. Lights on the dash come on with the key. I get 12v to the injectors.
The security light now stays on. I've tested the resistance of the key and it is still in spec. I tested the continuity of the wires to the ECU and they're not broken with 0 ohms. Tested the key side of the circuit too. I'm starting to think more and more that my ECU is dead. Does that track? Am I crazy?

The ECU has nothing to do with the engine cranking over. That is a function of thr VATS module and starter relay.

**Resin** · 4 Weeks Ago

I just jumped the outside two wires on the starter relay and it cranks again. Is the VATS not part of the ECU?
It's gone back to no spark at the plugs now though too.

**Resin** · 4 Weeks Ago

It's a 1995 350 block with vortec heads and a custom burnt chip. Not exactly L05 but closer.

**Resin** · 4 Weeks Ago

Let me check for resistance between the middle post and the shaft then. Would that be telling?

**Resin** · 4 Weeks Ago

0 ohms from the distributor shaft to the intake manifold. Open loop from the coil post to the shaft.

**Resin** · 4 Weeks Ago

8746-1.jpg
The starter solenoid looks like it us run through the ECU. Am I interpreting that wrong?

**dave w** · 4 Weeks Ago

It appears to me that the starter solenoid sends a voltage to the computer that the engine is being started cranking.

**Resin** · 4 Weeks Ago

Sounds good. That makes sense.
So I have two separate issues now.
Next thing that I'm going to verify is that the Rotor is actually spinning. It seems that would explain the issue better than the ECU not working.
I didn't think about it till I had already left the shop last night.
Thanks all for your input. I hadn't even thought about the voltage grounding through the distributor shaft but that prompted the idea that it isn't spinning at all, or at least intermittently.

**steveo** · 4 Weeks Ago

a weak coil will sometimes have enough output to jump one gap but fail to jump the second one. takes quite a big spark to jump the distributor and the spark plug. seen it a few times.

**Resin** · 4 Weeks Ago

A combination of a low battery and bad spark plug wire seems to have been the culprit on the spark issue. I think steveo was right. Now I have a different issue. The TBI is spitting fuel like a backfire and it actually caught the unit on fire. That is likely a valve issue right?