No Spark 85 Caprice

[RageCage]

OK, thanks for the tips on testing for spark. I used both methods, the timing light and watching the plug. No spark either way !

SO now what? I have the HEI ignition, which has the "integral coil" in the cap, and also a "module" in the cap. I also have some unit bracketed onto the passenger fender (Electronic Spark Control ???) I have looked in my Chilton's and haven't gotten much help there.

I'm going to take off the cap and just see if maybe the rotor is totally shot (an easy fix).

But if it's not the rotor, what would it be, and how could I test for it?

Thanks

[RageCage]

Well, it started up again, after I let it cool down for 7.5 hours. I checked the rotor. It looks OK. A little rusty, but since there is no spark passed from it, in the HEI, I think it's OK.

I found out the module mounted to the fender is a MAP sensor.

[MagicRat]

If it starts up when cold, but dies when it warms up, and has NO spark when warm, it's likely your coil is bad.
If the rotor and cap look poor, its time to change them, too.

Modules usually work perfectly or not at all, so if it runs, the module is propably okay.

[RageCage]

Originally Posted by MagicRat

If it starts up when cold, but dies when it warms up, and has NO spark when warm, it's likely your coil is bad.
If the rotor and cap look poor, its time to change them, too.

Modules usually work perfectly or not at all, so if it runs, the module is propably okay.

MagicRat, Thanks. I appreciate the info! Is this the "pickup coil" which is under the rotor, and which requires removal of the distributor, to replace? Lots of labor?

And I'm curious. Why does the car run fine, once it starts cold, and runs fine while it's warming up, and even when it's hot ? Why isn't the "no spark" condition happenning when the car is running and warm?
Why only during startup and warm?

Rage

[bobss396]

The ECMs are notorious for breaking down when they get hot, even warm. I've had them shut the car off under power, I've had a no-start condition when I've had the car sit for like 20 minutes. If I was driving it making stops running errands, it was ok. But as soon as it sat for a short time, zero spark.

In both cases once I changed the ECM, it cured the problem. If you got a few bucks to spend, swap out the whole distributor for a remanufactured one. But the ECM will run about $45.

Bob

[RageCage]

On closer inspection, I noticed the rotor had a dimple worn into it
where it pressed against the cap button, and also had a small rough
spot inside that dimple. (It had a * LOT * of miles on it).

So I bought a new rotor. The new one has a stronger tang on it. It
sticks up farther, to press against the cap button. The old one had
sagged lower, and maybe it was just barely connecting to the cap button, and that dimpled part was def not touching the flat cap button. Thebcap button is worn flat but still sticks out from the cap a bit.

The car starts much faster now when cold or hot. It also starts now
when warm, although sometimes it takes some playing with the gas pedal.

So, I am cautiously optimistic that the new rotor solved the problem.
Still more testing to do before I am sure.

Thanks.

[1986Z28]

i would check the coil also

[RageCage]

Back to the drawing board. Got the "no spark" again, when warm. It was starting OK for 2 days, after I put in the new rotor. I couldn't test the voltage at the cap, since I was stranded at the time, but I'll try to recreate the "no spark" in my driveway, then test for voltage at the cap's battery connector.

[beat88ls]

My 86 s10 did the same thing; it was a 5 speed 4 banger. If I stalled it or shut it off when at operating temp it wouldn’t start for several hours. I dicked around for a few days replacing cap, rotor, everything I could think of. I eventually sent it to my mechanic. He replaced something called a halifax switch in the distributor. Ive never heard of it, but after he fixed it I never had the problem again. Sorry if this doesn’t help

[RageCage]

Update. Finally fixed it (I hope). It's been starting at all times for about a week now. I called my mech and he said to try replacing the ignition control module. I did, and that apparently has fixed it !!!!!