1999 Chevy Blazer P1351

I am curious as to why you think the dealer is wrong and you are right?

1. Because I replaced the module and this morning the starting symptoms were exactly the same. 2. The service manager told me, " The technician feels the problem is the ignition module". I translate THAT statement to: " You said you only wanted a diagnosis, so we aren't going to check anything just for a diagnosis charge. All you get for that is a guess." I will have the new module checked this evening just in case it is bad. It is an aftermarket module. It is a brand name not the store brand. I have never had a failure of this brand in my life. But the posibility is there. I've been wrenching for 45 years so my experience with this brand is extensive.

Have you checked all your grounds and associated wiring? The issue is "voltage high" which usually means an issue on the ground side of the circuit.

My exploration this far has been ohming and jumping the power side. I have ignored the negative side. I have the earliest service manuals available for these models. Bought vehicle new. I always order service manual first thing. Will follow your suggestion and check grounding. Thanks.

Thanks for schematic. After covering the same ground again; ohming, jumping etc. I still found nothing. I decided to cover the fuel side AGAIN. Put two ounces of gas in TB and it fired right up. Hooked up pressure gage again this time it was below minimum. Even at that pressure was bleeding off 10 psi in 20 minutes. That pointed to check valve or pressure regulator. Went to bed. Thought about it in depth. If it is the regulator; the gas has to be going somewhere. Next morning I checked oil level. Sure enough it was almost a quart high! Changed out spider assembly. Installed new premium rotor and cap. Oil change. Cycled key three times; Started on first crank! I think repeated cranking with marginal ignition components will cause the VCM to throw a intermittent P1351.

I wouldn't bank on that theory. You could have disconnected something during testing that set the code. Lets see if it sets again after clearing.

Time will tell.