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No spark?

Ok, went out to pull the distributor apart and noticed some corrosion/rust on the center terminal of the dist. cap. Pulled the other end off the coil and the coil terminal was coated heavily with white powder over its entire surface. Cleaned up and applied dielectric grease--but now it's too cold outside for the truck to crank (-20), so I've got it plugged in and waiting for it to warm up . . . .
 
Cranked with cleaned up coil to cap wire, nothing. Have to pull the external ign. coil to get the cap off, so tested it inside. All fine except secondary resistance reads low (4.8Kohms instead of 6-30Kohms). It's a MSD Blaster GM coil, not sure if the low secondary would cause no spark, based on past experience the numbers in the manual are a ballpark figure. Advice on this?

I'll continue with checking pickup coil and module, book says pull the dist. to check pickup coil? Anyway, it's tight back there and cold fingers don't help. Coffee break every half hour--pee break every 45minutes hehe.

Edit: almost forgot, I found a used ign. module in the glove box . . . .
 
Ok, pickup coil tested good, pulled the module and am looking for a place that will test it and the one I found in the glovebox. Also am getting only 11.6V at the BATT terminal of the coil--shouldn't it be battery voltage? Batteries are at 12.08 and 12.59V . . .
 
Eh, voltage at the coil is out of the cab (ignition switch or fuse panel, can't recall) so you've got some wiring distance and numerous connections. 1.5V drop isn't good, but isn't abnormal at the non-battery end of the wiring.
 
OK, swapped in the ign. module I had in the glove box with no change. This leaves several possibilities.

1) If this module and the original one are both bad, I need a new one, but why is the truck eating modules?
2) If this module is good, then the original one is likely good as well, and I need something else, most likely a new coil.

Sounds like I need to find someone to test my modules . . .
 
You got schucks, checker, or Kragen's up there? Autozone?

I've heard CSK will test them, I'd suspect others as well.

GM modules are supposed to have a white or yellow "bubble" on top of them if they fail. Never got a chance to test that.
 
None of the above, might be able to get it done at Canadian Tire (kinda like autozone I think) otherwise it's dealership time. If the module(s) are bad, I'd like to figure out why it's eating them like that. Although the pickup coil tested good, (even when I wiggled the wires around there was no change in resistance), the wires were cracked in several places. Mebbe I should just bite the bullet and get a brand new distributor if the module is actually gone.

In the meantime I'm seeing the upside of getting into the TBI system and getting familiar with it, so in the end it's all good . . . I also found and fixed a damaged vacuum hose.
 
:mad::mad::mad: Well, I'm pretty much fed up with this stupid truck.

As I said earlier, I tested the coil, and secondary resistance was low, so I bought a new one and installed it. Nothing. -$78

Checked resistance on the coil to cap wire and got infinite resistance up to the 20K range, so I replaced that. Still nothing. -$20

Installed, in turn, the original module, the one out of the glove box, and then a brand new one from GM. Still nothing. -$125

Checked for switched power at the injectors, that's good. What's supposed to happen at the TB when I crank the engine? Shouldn't I see fuel spray from the injectors?

Bypassed the MSD 6A box, then plugged it back in. Still nothing.

I need this damn truck on the road, it was supposed to be a no worries vehicle, and I'm getting pissed off. Coffee break time.

Next step is to rig some kind of light to check if the injectors are pulsing, and make sure there is fuel at the TB. Still not sure why I've got no spark though . . .
 
OK, I'm a goldurned carnsarned freekin' stupid moron . . . . Pulled a couple plug wires, stuck a spare plug in and grounded it, then had my bro crank the truck, I've got great spark. Not sure why my inductive timing light doesn't pick it up, and still not sure why the truck's not firing, but this whole thread is gone to freekin' waste.

Sorry guys, please excuse me while I kick my arse around the room a few times. Dangit.
 
Does the fuel pump cycle for 2 seconds when the ignition is first turned to the ON position? If not you either have a bad fuel pump, relay, and or back up pressure switch. I would lay the odds on a bad fuel pump at that point though since it is doubtful that the relay AND pressure switch would have went bad at the same time.
 
Well now we know you do have spark and the problem is not ign related:D
Dont kick yurself too hard. You will abusing yourself enough when you have to drop the fuel tank.
As 4x4 high said most likely fuel pump. Starting and dieing, long cranking time are symptoms of a bad fuel pump.
If you want to check the relay, its on the firewall with a red lead hanging out not connected to anything. Hook up 12v to the red wire. Fuel pump should run.
Even if you can hear the pump run it still can be bad. Only way to tell for sure is hook up a pressure guage.
 
Have your brother crank while you spray a bit of starter fluid into the throtle body. If it fires then you have a good indication as well that it is simply a no-fuel issue.
 
4x4HIGH called it first :D Right hand fuel pump is bad, I had my bro turn the switch to run, first with the rh tank (the full one that I was running on), then with the lh tank. It had about 1/8 tank left in it, flipped over to that tank, switched on, I heard the pump run, then the truck fired right up.

To think that I spent the last two days swapping ignition components when all I had to do is switch tanks :doah:

New fuel pump on the way :rolleyes: Just think of everything I learned--1) an inductive timing light is not a reliable method of determining spark, 2) an intimate acquaintance with the ignition components on my first TBI vehicle, 3) how to check the fuel injectors for correct (electrical) operation, etc. :haha:

At least now I can diagnose/change ignition components on the side of the road, and I even have spares for the glove box!!!
 
Wrench said:
4x4HIGH called it first :D Right hand fuel pump is bad, I had my bro turn the switch to run, first with the rh tank (the full one that I was running on), then with the lh tank. It had about 1/8 tank left in it, flipped over to that tank, switched on, I heard the pump run, then the truck fired right up.

To think that I spent the last two days swapping ignition components when all I had to do is switch tanks :doah:

New fuel pump on the way :rolleyes: Just think of everything I learned--1) an inductive timing light is not a reliable method of determining spark, 2) an intimate acquaintance with the ignition components on my first TBI vehicle, 3) how to check the fuel injectors for correct (electrical) operation, etc. :haha:

At least now I can diagnose/change ignition components on the side of the road, and I even have spares for the glove box!!!
Click to expand...

1) Best method to determine spark is to grab the bare terminal wire end and have someone crank, you'll know REALLY quick if you have spark or not. :D

2) Becoming familiar with your truck is never a bad idea.

Glad to have helped and that you have a new pump on the way. :thumb:
 
4X4HIGH said:
1) Best method to determine spark is to grab the bare terminal wire end and have someone crank, you'll know REALLY quick if you have spark or not. :D
Click to expand...

I've done that more times than I can count, the anticipation is good for more adrenaline than I like at once :haha:

Thanks very much y'all--I'm starting a 350 build thread with interesting quirks, so I'll have lots more questions :D
 
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