Testing for Spark PRESENCE by Yourself & in a Pinch

[1987 GMC Jimmy]

Nothing too fancy here, but when emergencies happen and/or you're alone, your brain can get a little cloudy when it comes to addressing the problem. I know mine does. It's just me here, and I lost spark in my car tonight. This is the first time it's left me stranded somewhere. It died very spontaneously while driving down a parkway and left me in a bit of a bind. Anyways, I got it back here and decided to dig in. I've got a roommate, but he doesn't know diddly about anything, and I didn't want to pull him from his very important video game (sarcasm - I could give a ****, but I'd rather work alone unless I have someone who knows a couple things and is willing to help) so I figured I'd verify lack of spark. I don't have a remote starter with me, and I didn't have anyone to turn the key while I grounded a removed plug. I have an inline spark tester, but it's an unreliable piece of crap. So I'm left with a timing light that I always haul around. I hook it up and unfurl the wires so it'll reach to where I can push the button and turn the key. Turn the key, it lights up, the car starts almost immediately after, the light stops, and the car dies after about five seconds of running. Try again and no more light so I know I'm not getting any spark. This is a Bosch light with a little button, but if you have a light with a trigger, and it won't reach, you can tie the trigger down with a zip tie or something, point it towards you, and go for it. This is a poor test for spark QUALITY, and it was only intended to confirm my suspicion of a failed ICM. I can reconfirm by taking it to Autozone, but that's gonna involve me taking a streetcar and a bus now, and this gave me the peace of mind in ordering a new one. Again, nothing special, but I figured I'd share to maybe help someone else down the road in a similar predicament who wants a quick answer to the question of do I have spark.

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[chengny]

Or, if you didn't have an inductive timing light with you, try this:

Disconnect a wire at the plug end (#1 is a good choice - it's a nice long one). Stick a bolt or a screw in the boot. Look around for a spot where the screw/bolt can be observed through the gap between the hood and cowling. It's best to find a spot where the bolt can be suspended - so that it is close to, but not touching, a good ground. Also, at night any number of places will work. But in broad daylight, it sometimes helps to find a spot in a shaded area.

 

[MtBraun]

Nothing too fancy here, but when emergencies happen and/or you're alone, your brain can get a little cloudy when it comes to addressing the problem. I know mine does. It's just me here, and I lost spark in my car tonight. This is the first time it's left me stranded somewhere. It died very spontaneously while driving down a parkway and left me in a bit of a bind. Anyways, I got it back here and decided to dig in. I've got a roommate, but he doesn't know diddly about anything, and I didn't want to pull him from his very important video game (sarcasm - I could give a ****, but I'd rather work alone unless I have someone who knows a couple things and is willing to help) so I figured I'd verify lack of spark. I don't have a remote starter with me, and I didn't have anyone to turn the key while I grounded a removed plug. I have an inline spark tester, but it's an unreliable piece of crap. So I'm left with a timing light that I always haul around. I hook it up and unfurl the wires so it'll reach to where I can push the button and turn the key. Turn the key, it lights up, the car starts almost immediately after, the light stops, and the car dies after about five seconds of running. Try again and no more light so I know I'm not getting any spark. This is a Bosch light with a little button, but if you have a light with a trigger, and it won't reach, you can tie the trigger down with a zip tie or something, point it towards you, and go for it. This is a poor test for spark QUALITY, and it was only intended to confirm my suspicion of a failed ICM. I can reconfirm by taking it to Autozone, but that's gonna involve me taking a streetcar and a bus now, and this gave me the peace of mind in ordering a new one. Again, nothing special, but I figured I'd share to maybe help someone else down the road in a similar predicament who wants a quick answer to the question of do I have spark.

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That's exactly how I tested for spark in my ongoing TBI troubleshoot. I think I even have the same light. Cheers!

 

[Dougnsalem]

Its easier just to hold the wire. No tools required. You'll know if you have spark, and how good it is....

 

[Robert Samaniego]

When I'm trying to find a cylinder that is not firing, I get a spray bottle with water and with it running I spray the header primaries individually . If the water evaporates as soon as it hits the header I know that I have a good cylinder. If it runs down the headers without evaporating it tells me I've got a cylinder that is not firing. Then of coarse I go check the wire and the plug along with the distributor.

 

[Honky Kong jr]

Its easier just to hold the wire. No tools required. You'll know if you have spark, and how good it is....

That’s the asylum method. Just put your belt between your teeth or a stick if you don’t wear a belt.

 

[Dougnsalem]

Well, yeah. Why do you think they filmed One Flew Over The Cuckoo's Nest in Salem? We're all like that...

 

[Honky Kong jr]

Well, yeah. Why do you think they filmed One Flew Over The Cuckoo's Nest in Salem? We're all like that...

I was like wait Salem....... I had to look, your in the other Salem not the witch Salem lol

 

[Snoots]

Its easier just to hold the wire. No tools required. You'll know if you have spark, and how good it is....

This works WAY better if you're standing in water.

 

[Dougnsalem]

This works WAY better if you're standing in water.

It's Oregon. We always are.... Lol

 

[Dougnsalem]

I was like wait Salem....... I had to look, your in the other Salem not the witch Salem lol

That's ok. I thought you were in Colorado....

 

[bucket]

When I'm trying to find a cylinder that is not firing, I get a spray bottle with water and with it running I spray the header primaries individually . If the water evaporates as soon as it hits the header I know that I have a good cylinder. If it runs down the headers without evaporating it tells me I've got a cylinder that is not firing. Then of coarse I go check the wire and the plug along with the distributor.

That spray bottle is also really good for finding failing spark plug wires. A little mist here and there, then look for arcs.

 

[Honky Kong jr]

That spray bottle is also really good for finding failing spark plug wires. A little mist here and there, then look for arcs.

And if you run a grounded test light along them, but not touching, while running and wet you can do a fine spark jump test.

 

[1987 GMC Jimmy]

Another thing I found today... My 13 month/12,000 mile old AC Delco ICM did fail on the bench, it failed due to overheating, and I’m pretty sure it was my fault. I say that because it passed the first test but failed the subsequent ones when it was warm and because this module (third one) didn’t come with a packet of heat sink compound. I made the almost certainly false assumption that the generous amount stuck to the distributor from the previous two modules would be enough. I was wrong, and if you find yourself without a packet of grease, please go buy some instead of being an impatient dummy like me. The Autozone part number for it is SL203. It’s two little packets in a box. I also bought a disposable spare ICM for the glovebox [Duralast DR124 for ESC distributors (many 81-86 trucks, certain 80-90 GM cars)], which I should have done a year ago. The Delco module is coming from Rock Auto Saturday, and hopefully it’s not a dud.

 

[Snoots]

This is GOOD stuff!
https://www.amazon.com/Arctic-Silver-AS5-3-5G-Thermal-Paste/dp/B0087X728K?tag=amazongs-20

Always clean off the area where the module mounts. Don't leave any old grease on it.
Alcohol (not the drinking kind) and a rag.