no spark trying to diagnose why

[moofus02]

1995 s10 blazer 2dr 4x4 4.3L vin w cmfi engine. kept blowing fuses, shorted wire to fuel pump. fixed that and now has no spark. found a thread on testing ign on a 98 or 99 but wireing codes were different. I have power to coil and ign module on pink wire. don't think I'm getting a pulse but not sure how to diagnose that. all fuses are good. emission tag says it is obd1, has 16 pin connector but the pin layout looks to be obd2. engine has oil pressure so cam is turning but no spark at coil wire. I don't want to wast money changing parts, i want to trace a wire problem or diagnose a bad part. someone changed the trans and left wires lose and exh melted them, that was my fuel and fuse problem. don't find any pinched wires at distributor. any advice is appreciated. brian

[Schrade]

I have power to coil and ign module on pink wire. don't think I'm getting a pulse but not sure how to diagnose that. all fuses are good. emission tag says it is obd1, has 16 pin connector but the pin layout looks to be obd2. engine has oil pressure so cam is turning but no spark at coil wire.

You say "power to coil", and "no spark at coil". Which is it?

You can pull the ig module, and take it to Advance / Zone and they'll test it for free. They can only test it cold tho', unless it's pulled from a car you just drove there.

So if it tests bad, it's bad. But if it tests good, it COULD still fail when hot (but it WILL start the car).

Make sure whenyou put in the new one, you use heat sink paste. Get a tube, or get some from a computer shop on the way home.

[moofus02]

I have power everywhere but no spark. I don't know if its the computer, icm or pickup in distributor that's not tripping the coil or possibly a bad wire. looking for info on wiring and testing so I can fix this without wasting money or driving 50 miles to have stuff tested. any help is appreciated. Thanks Brian

[Schrade]

Originally Posted by moofus02

I have power everywhere but no spark. I don't know if its the computer, icm or pickup in distributor that's not tripping the coil or possibly a bad wire. looking for info on wiring and testing so I can fix this without wasting money or driving 50 miles to have stuff tested. any help is appreciated. Thanks Brian

Only SURE thing I can tell you is to go to a local mechanic, and see if he has Mitchell's Online, or ALLData, and get him to printout diagnostic procedure for ??? (exactly what the problem is ???)

What did you do to fix the shorted wire to fuel pump?

Are you sure that you have power to the coil? Have you checked for spark at each spark plug wire? You can check each wire AT the distributor, but it's tricky...

I have a Chilton's for 'S'-vehicles '94 - '99 that you can have for postage. They're not the best tech info, but sometimes they have enough to steer you in the right direction... PM me...

[skyzend]

I had a similar experience with my 1999blazer.
Basically would not start with symptoms of either no fuel or no spark.

Plan A - no fuel
I checked the fuel pressure and it was good so that ruled out anything towards the fuel pump side.
You should check to ensure that after you corrected the fuel pump wiring that it actually delivers the right amount of pressure to the system. If the pressure is not at the factory minimum then the injectors will not fire and all bets are off ... the symptom actually looks like no spark ...

Plan B: no spark
As I mentioned I went through the steps above and ruled out problems with fuel as a root cause.
To shorten the story, the root cause was the ignition wiring. It was original factory wiring and had over 300,000km of use. The internal impedance increased to the point where it just would not function.
More specifically, the coil wire to the distributor, which carries in its lifespan, 6 times the number of voltage sequences than any of the spark plug wires (4.3l 6 cylinder). If this goes bad all bets are off, everywhere.
Have a look at the coil area at night while trying to start and you may see arcing from under the coil boot going to ground. this is usually acompanied by ticking. If you have 1 or more bad spark plug wires, after starting the truck you might see intermitant sparking. This will become all the more prominant in damp weather
When installing new wires, use dielectric grease as this helps the wire boots slide on and insulates the connection from moisture and arcing problems.

Hope this helps