Spark to distributor but not to plugs - Bad Riddle (Page 1/2)
Lobster JUN 22, 11:54 AM
Hi All, I'm new to Pennock's but hoping someone can shed some light on this.

87 Fiero GT - son picked it up for graduation. On the drive home (40 min), it stalled. From his description - "it studdered, I pushed the clutch in and it smoothed out, I revved it a couple of times and that sounded good, then I downshifted because I had slowed down, and when I dropped the clutch it stalled completely" - I thought it must be old gas that had plugged the fuel filter, etc.

We towed it home and it ended up being spark, fuel pressure is 45psi. So we (in this order).....

changed the distributor cap and rotor - no change
changed the distributor (complete) - no change

Symptoms include....

rotor spins when engine cranked,
when I connect any spark plug wire to the coil - there is spark when grounded to the engine
No spark from any of the 6 spark plug wires when connected to the distributor and grounded to the engine (actually we do get the odd spark here and there but just 1 maybe 2 during a 6 second crank,

Because we have spark from the coil to the distributor and its there no matter what wire I use I want to say that it can't be the wire set or the plugs - car ran fine before it died. Is there something I'm missing? In the way it died, does that give anyone an idea that it could be something other than the rotor or cap?

Really wish I could get this on the road for him, thanks in advance!
theogre JUN 22, 11:58 AM
Pull tach filter and
See my Cave, HE Ignition

------------------
Dr. Ian Malcolm: Yeah, but your scientists were so preoccupied with whether or not they could, they didn't stop to think if they should.
(Jurassic Park)

The Ogre's Fiero Cave

Lobster JUN 22, 12:43 PM

quote
Originally posted by theogre:

Pull tach filter and
See my Cave, HE Ignition




Thanks theogre, when I pull the coil wire off the distributor and put a spark plug into it and ground it to the block, I have really good, continuous spark. When I put that wire back onto the distributor and use the regular spark plug wires to check spark in the same manner (spark plug grounded to block) I do not get spark. Impossible or am I missing something. I did try unplugging the tach but it made no difference.
theogre JUN 22, 12:58 PM
Get a "Spark tester."
If adjustable set to ~ 25KV.

Example: Non-adjustable


"holding" a plug wire near ground have many problems and can damage the coil and other parts.
Lobster JUN 22, 01:11 PM

quote
Originally posted by theogre:

Get a "Spark tester."
If adjustable set to ~ 25KV.

Example: Non-adjustable


"holding" a plug wire near ground have many problems and can damage the coil and other parts.



I would grab one but as I mentioned I do have spark with the existing spark plugs and wires so I know they work. Just trying to figure out where the spark is going. It is definately well and good at the end of the coil wire (going to the top of the distributor) but it dies between the cap and the plugs. My understanding is that there is only the cap, rotor, plug wires and spark plugs after that. Is there something else that would stop the spark from reaching the plug wires?
sanderson231 JUN 22, 01:17 PM
Have you tried rotating the distributor with a grounded spark plug connected to a spark plug wire?. It sounds like the coil is firing when the rotor is not pointed at a spark plug wire.
Lobster JUN 22, 01:18 PM
Member 4LB21HP posted about the exact issue I'm having back in 2010 but he didn't say what fixed it and I know he did because he's posted after that Would be great to hear what it was. Here's a copy of his original post. Just for clarification, I've done everything on his list except replacing the distributor twice, I've just done it once but there is spark at the coil wire so I think all is good there

*************
OK so I have a no start situation. The car is an 87 V6, it will turn over but not start. Things I have done to try to fix the problem:

Checked for 12v at the coil, Good
Checked for 12v at the disttibutor, Good
Check to make sure that the engine is grounded, got a 0.00 for resistance, excellent.
I recieve a tach reading at the gauge while attempting to start
Replaced the distributor, completelty new, with Pickup and ICM
Replaced the coil
Checked for spark with spark tester, I can get spark from the coil to grounded on intake, but not from any of the plug posts on the distributor (yes coil to distributor wire connected)
Checked to make sure that the rotor actually spins.
Replaced the cap and rotor
Replaced the distributor a second time, just for for spite

Is there anything else out there that I have not though of as a test or replace? It makes no sence to me that everyting has been replaced and the distributor will still not pass on the spark!!! Any help would be greatly appriciated!

************
Lobster JUN 22, 01:26 PM

quote
Originally posted by sanderson231:

Have you tried rotating the distributor with a grounded spark plug connected to a spark plug wire?. It sounds like the coil is firing when the rotor is not pointed at a spark plug wire.



Thanks, I did try moving the distributor clockwise and counter clockwise as much as I could but it didn't change anything. We marked where it came out and put it in likewise. I can rotate it equally in both directions but no luck.

This might sound crazy but could a person put foil or wire between two poles inside the distributor, crank it and see if there's spark to that plug wire or would that be to hillbilly and cause damage to other components? I'm thinking tin foil or something light that wouldn't destroy the distributor with a short 3 second crank
Patrick JUN 22, 02:31 PM

quote
Originally posted by Lobster:

Just trying to figure out where the spark is going. It is definately well and good at the end of the coil wire (going to the top of the distributor) but it dies between the cap and the plugs.



"well and good" is not too technical of a description. You need to determine if the spark is able to jump a 1/4" gap. It should be able to snap across such a gap in atmospheric pressure with no issue whatsoever.


quote
Originally posted by Lobster:

My understanding is that there is only the cap, rotor, plug wires and spark plugs after that. Is there something else that would stop the spark from reaching the plug wires?



I don't know what it's called, but make sure the spring loaded center electrode thingy inside the cap is present and is protruding far enough to make contact with the rotor.
Lobster JUN 22, 02:40 PM

quote
Originally posted by Patrick:

I don't know what it's called, but make sure the spring loaded center electrode thingy inside the cap is present and is protruding far enough to make contact with the rotor.



Fair, I'm not sure how to measure that spark off the coil but it's bright and constant, not something I'd put my tongue on to check I have 2 rotors and 2 caps but neither work, both buttons appear to work (spring bit goes in and out).