95 c1500 4.3 TBI has fuel and spark, cranks, no start

[unpredictable1]

Guilty of throwing a couple of parts at it today, changed the coil and the ignition control module. The coil is fairly old looking, still had it's metal riveted mounting bracket that I transfered over to the new one. The ignition control module, those bolts were fairly corroded at the top and the part was stamped GM (it looks like it's been in there a while)

Retraced the wires and plugs for firing order. Still doing the same thing. She will do a ever so slight bump as if she's going to catch but that's it.

I wonder could it be the distributor? I was also wondering if an injector was dumping too much fuel down in her but I tried pulling the fuel pump fuse - still the same. (edit: this was after i tried starting her with the pump live so fuel was present)

I do have a close up video of fuel spraying - not sure anyone can tell anything from that other than both injectors are firing.

 

[unpredictable1]

I got a remote starter switch coming hopefully today - hard to do some of the testing by myself.

It's a bit frustrating when I go back and watch the videos I have of this thing idling last week once I got the plugs/wires can and rotor done!

 

[unpredictable1]

Tested the ignition coil I removed after watching a video, low reading was .8 ohms (200 ohms), and the high reading was 8.11 (20k ohms)

The video I used:

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[Schurkey]

The video I used:

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Another example of someone who doesn't know what the hell he's doing, pretending to be an expert on Youtube.

1. I'm please that he remembered to subtract the resistance of the test leads from the primary resistance measurement. It's the only thing he did in the entire video that exceeded my expectations.

2. The guy doesn't understand decimal points vs. meter scales. When testing the secondary resistance, the 0.3 ohms of resistance in the test leads is TOTALLY MEANINGLESS. Here's why--and why he screwed-up. The meter shows 8.03 on the 20K scale, which as he explains is actually 8,030 ohms. Then he subtracts the previous measurement of 0.3 ohms in the test leads from an indicated 8.03...but forgets about the change in the meter scaling. So he incorrectly subtracts the lead-resistance ohms from the 8,030, and at 13:10 in the video he claims that leaves about 7 thousand something ohms for the true value, when if he'd gotten his decimal points correct, he'd have come up with 8,030.0 - 0.3 = 8,029.7 ohms. Three tenths of an ohm is totally meaningless in this case.

3. The guy never does check to see if either winding is grounded. Testing from the either (preferably both) the primary and/or secondary connection to the frame of the coil is required. Obviously, you're hoping for zero continuity--the windings should be insulated from ground.

4. The ohmmeter can tell you that the coil is defective. If your primary or secondary resistance is out-of-spec, the coil is defective. If either winding is shorted to ground, the coil is defective. But the coil can measure good in all three ohmmeter tests, and STILL BE DEFECTIVE. Therefore, you MUST test coil voltage output using a spark tester calibrated for the design of the ignition system--either an old-style ballast resistor in line with the coil, or--in this case--calibrated for HEI which uses no ballast resistor. The coil must pass all three ohmmeter tests, AND reliably jump the gap of a calibrated spark tester to be considered usable.

Fifteen minutes of incomplete information, AND an actual mathematics screw-up. I watched the video at 1.5 speed, and I still want my ten minutes back.

 

[unpredictable1]

Alright I'll toss that guy's video out then.

Got my remote starter switch and grabbed a test light, (the latter I completely forgot mine at home) connected it up, figured I'd check a couple things before shutting down for the night:

- pulled the coil wire off the coil, spark is coming from the coil, it jumped a decent gap to the test light, at least an inch and I could even hear it. It looks better than the spark I had before but I know looks can be deceiving.
- same with pulling the coil wire from the distributor cap, spark travels a fair distance and stupid me I zapped myself pretty good - this time I didn't just see it and hear it, I felt it. lol

Tomorrow I'll recheck spark to the plugs and I'll see if I can get one of those HEI plug testers here soon. Nothing around here has anything and I have to travel minimum 30-40 mins to pick anything up.

Having this remote starter switch is a game changer when you're on your own. Should be able to better test a few things tomorrow.

 

[unpredictable1]

Performance Tool W86553 spark tester should be here today

 

[unpredictable1]

Spark tester hasn't shown up yet, but I did a compression test and it went as follows:

2 170
4 170
6 170

1 175
3 175
5 175

The passenger side did get a touch above 170 (maybe the width of the gauge needle)

All the new plugs I put in, all looked the same. A little sooted up that's about it. Just waiting on that spark tester - next day doesn't really mean next day out here lol

 

[unpredictable1]

I decided to connect the coil and visually check spark on the plugs while waiting for that tester.

Well, it appears pretty damn weak looking and only sparks a few times that you can anticipate with the firing order and then seemingly stops sparking altogether while cranking. Or maybe it was so faint I couldn't see it out in the sunlight - which you should be able to.

I tried 3 different plug wires, all the same. Definitely not like the spark I had at the coil and from coil to distributor that's for sure. Keep in mind this truck did idle several times with these plugs/wires/rotor/cap. Albeit rough and rich probably from poor spark now that I look back on it - she did idle.

Seems to be between the distributor and plugs - going to test what's coming off the distributor where each wire plugs onto, the rotor seems on good and straight when I had it off yesterday and the cap still looked fine inside.

 

[chris032188]

Question - if you hold gas wide open does the truck try to fire? I had similar symptons when my truck would get hot. It ended up being the temp sensor telling ECU it was like -40 out and flooding the hell out of the engine.

 

[unpredictable1]

Question - if you hold gas wide open does the truck try to fire? I had similar symptons when my truck would get hot. It ended up being the temp sensor telling ECU it was like -40 out and flooding the hell out of the engine.

aside from this spark issue, yes, I found that the times she really sounded like she was going to catch and fire up was when I held the pedal to the floor. Where this thing hasn't been driven in quite a while I think I have a few gremlins I'm chasing lol