I have been fighting with this problem for some time now and have checked almost every thing. It all started off with me blowing a ECM B fuse. So i replaced the fuse and the truck would not start. I was getting fuel so i ceheck for spark and i had none. So i checked all the components. I checked my pick up coil restance, had the ignition modual checked and checked the coil and the ECM. What else could this be it really is confusing me as to why i am not getting spark
CK5
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Not getting any spark can't figure it out
- Thread starter 1979jimmy350
- Start date
mudhog
THEGAME
im sure you already checked this but are you getting power to the coil?
yea i am getting power to the coil. How likley is it for the magnents to go bad in the distrbutor? is there any easy way to check for this?
ttt
readymix
3/4 ton status
I just went through this last week. My magnets had worn out.
Keep in mind that if the magnets wear out then you will have two symptoms.
1. No fuel...injectors not firing(if TBI)
2. No spark
Both led me to believe that i had a faulty pick up coil. After replacing it 3 times i hooked up the output of the pick-up to my DVM and spun the mainshaft with a drill. No output at all. It should be around 1Vac or so to fire the EST.
When you remove the distro and spin it slowly by hand you should feel the magentism between the mainshaft and the reluctor.
Keep in mind that if the magnets wear out then you will have two symptoms.
1. No fuel...injectors not firing(if TBI)
2. No spark
Both led me to believe that i had a faulty pick up coil. After replacing it 3 times i hooked up the output of the pick-up to my DVM and spun the mainshaft with a drill. No output at all. It should be around 1Vac or so to fire the EST.
When you remove the distro and spin it slowly by hand you should feel the magentism between the mainshaft and the reluctor.
do you think that the starter will turn the shaft fast enough to tell? The distributor is still in the truck and i am 3.5 hours away from the truck. I am leaning twords the magnents because i replaced the pick up coil in it about two years ago
readymix
3/4 ton status
It could spin it fast enough to get a reading.
ok i had my brother spin it by hand and the most he could get was .9 AC volts. Now this is a V6. For comparision i have a TPI distrbutor in my dorm room and i was spinning it by hand and was able to get 2.5 volts. Do you think that that large of a difference could be caused by the fact that one is for a V6 and the other a V8 or is the V6 one most likley shot
readymix
3/4 ton status
.9Vac might not be enough, but don't quote me on that. What i would do is this test.
- Unplug the PU coil from the EST while the distro is installed, cap removed.
- Ignition on but do not try to start it.
- Use a noid light to jump 12Vdc over to the PU coil inputs on the EST. What you need to do is quickly move the noid light end from one pin to the other and back and forth. Every time you do this you are effectivly firing the HALL effect device in the EST. When you do this it should cause the coil to fire. You should see the spark from the primary of the coil.
Don't shock yourself
- Unplug the PU coil from the EST while the distro is installed, cap removed.
- Ignition on but do not try to start it.
- Use a noid light to jump 12Vdc over to the PU coil inputs on the EST. What you need to do is quickly move the noid light end from one pin to the other and back and forth. Every time you do this you are effectivly firing the HALL effect device in the EST. When you do this it should cause the coil to fire. You should see the spark from the primary of the coil.
Don't shock yourself
Leper
1/2 ton status
You will shock yourself. But, that is the easy way to test for spark. That is a good test. I will have to remember that.
readymix
3/4 ton status
That test is even easier if it is TBI since it will fire the injectors
That way you will not get shocked
That way you will not get shocked
opfor2
1/2 ton status
1979jimmy350 said:
How did you check the ignition module? I had mine go out on me and it did the very same thing, no spark, no fuel. I got a replacement module from AutoZone and guess what?? It was defective, installed an OEM ACDelco and she runs like new. I would replace the module and see what happens.
good luck
Dan..
readymix
3/4 ton status
Speaking of how to test. Can anyone find me a true schematic of the hall effect circut so i can make my own testor?
i had my modual tested at autozone they have a special machine for it
This isn't exactly what you are looking for, is it?
http://92b4crs.tripod.com/86wiring/dia-pics/22-0.jpg
I'm pretty sure my '88 Camaro service manual has a more detailed breakdown, if I get a chance to head out to my truck, I'll check it out.
http://92b4crs.tripod.com/86wiring/dia-pics/22-0.jpg
I'm pretty sure my '88 Camaro service manual has a more detailed breakdown, if I get a chance to head out to my truck, I'll check it out.
readymix
3/4 ton status
Not the type of schematic that i am used to seeing, but it is more detailed than most chevy diagrams. Don't think it is enough to build a tester from though.
Nope, guess the service manual portion isn't any more detailed than what I linked you to. If I do run across one, I'll let you know.
well finnaly got the truck running after two months of sitting. It turned out to be the ignition modual even though it tested good at auto zone
readymix
3/4 ton status
good to hear that.
