Stephen Bannworth

Is the truck running now? Did it run at all with no assistance since the snow storm? Sorry for questions just trying to get a check list of things that could be wrong!

Stephen Bannworth

Also If you spray fuel starter into the air cleaner will it start?

Firefox64

The truck is not running now. I have the proper gap on the spark plugs and there is no start. It did run for a bit before I redid the gap on the plugs but no start since. So to answer the question, yes, it has run since the snowstorm but never with the plugs having the proper gap. Everything else is either new or has been swapped with known good parts.....except the wiring harness. I've been looking at that and checking each of the wires from connector to connector and haven't found anything amiss yet. Thank God for factory service manuals and wiring schematics.

We did try starting fluid several times throughout the process. It has never kicked at all with the fluid.

Don't apologize for asking questions. I've been asking lots of questions to lots of people and somewhere there is an answer that will solve this. I really appreciate the thoughts and even though I've gone through a bunch of checks I'm going back and rechecking with each suggestion hoping to find what I've been missing.

Thanks for taking the time to offer the suggestions....

Mark

Firefox64

Well, after going over a few more things I still haven't figured it out.

I'm going to focus on the distributor and the wiring. The distributor gear does not seem worn at all and there is no code for a mismatch for the crank and cam sensors. I do not have much play at all when I try to turn the rotor so I'm figuring that the distributor gear is ok. Is there another possible failure with the distributor that I'm overlooking? It does have a new cap and rotor and a known good cam sensor.

Another thing that I'm wondering......is there a possible computer failure going on here? Is there some other component that might be causing my issues?

Thanks for all the help...

Mark

muncie21

See if you have a premature code (won't trigger the CEL if it is premature) in the PCM related to ignition voltage (high I believe) and if so, clear it and see if that helps. If the code keeps coming back, you may need a new PCM.

Firefox64

My rather inexpensive code reader is telling me that there are no codes in the computer. But will that code show up on my little Actron CP9125? I'm going to start going over everything in the ignition system again as this still seems like a spark issue.

Thanks, guys....

Mark

kevinkpk

If you have something impending or set, you will have a cel.

kevinkpk

What little I know, and through reading other posts about the distributor gear is either wear or the pin that holds it to the rotor elongates causing ignition issues. If you have someone to crank it, I'd suggest with an insulated screwdriver in the plug end, hold the shank 1/8" or so to the plug end, check for spark. Post back, also what color is the spark? This will eleminate ignition LESS the timing.

Firefox64

Well, after picking up a really nice spark testor, it seems that I have a decent blue spark on the 3 different cylinders I tried. So, I have compression, fuel and spark. I seem to have a timing issue. Mechanically it's good as the engine ran smoothly with the wrong spark plug gap so the higher demand for the spark to jump the wider gap must be changing the timing. How does that work? Oh, the questions I have.......

Thanks for the input. It's very much appreciated.

Mark

muncie21

Your ignition circuit should look something like the one below.


There are many potential things that could trigger a 'no-start' like you have and you've checked a good many of them. Do a search on the net using "P1351 code vortec" in the search string. I'm not sure if the scanner you have would pick this code up if it is still pending and hasn't triggered the CEL, but it's worth it, if just to get educated on how the ignition system works. I 'believe' the reason that PCM is part of the circuit is because it sets the timing, both during cranking and under normal operation. There's an outside chance the PCM isn't working correctly, along with wiring, grounds and other fun stuff Good luck with the troubleshooting and let us know what you come up with.

Here's a description of the 1351 code, pasted from the net:

DTC P1351 (ignition coil control circuit high voltage) CIRCUIT DESCRIPTION:
The enhanced ignition system uses the crank sensor in order to provide the timing input to the Vehicle Control Module (VCM). The VCM uses this reference pulse in order to determine the individual ignition spark timing for each cylinder. Once the VCM calculates the ignition timing, the ignition coil module on the Ignition Control (IC) circuit receives the timing signal. Each timing pulse received by the ignition coil module on the IC circuit triggers the coil module in order to operate the ignition coil. The secondary ignition voltage is induced, and then the secondary ignition voltage is sent to the distributor for distribution to each spark plug. The IC signal voltage ranges from about 0.5 volt to 4.5 volts.