Hello all, I have a 99 Tahoe 4x4 5.7L. Five weeks ago I went home to Indiana on leave (military), first time the truck had seen severe cold weather. It started having trouble starting when engine was cold (open loop). I could cycle the key a few times allowing the fuel pump to cycle then get it started. I just chalked this up to cold weather and went about my business. I went out to my brother’s house which is open field in the country and the temperature dropped to 8 degrees without wind-chill. Truck would not start at all. Spent the night there and was supposed to drive back that day. I called my other brother who lives in Indianapolis and had him bring down parts that all have sensitivity to humidity and cold weather. We changed out the coil and ignition module before checking for spark, I know I know, but had clean strong blue spark. We shoveled the driveway and got it pushed into the barn. I checked the fuel pressure and it was around 60psi ruling out the fuel pump. I thought maybe the diaphragm in the fuel pressure regulator was going out, cold weather making it worse. I put a hair dryer on the intake above the regulator for a few minutes and it started right up. I loaded up and drove 13 hours home only shutting it off for gas. Once I got it home it was back to the same thing, no start, cycle the key a few times and it would fire up and start rough then smooth out. I thought I’d change the fuel pressure regulator when I could get some time. I did some travel overseas for a few weeks and it did the same thing for a few days, until it finally died for good. Now it won’t start at all, smells flooded after cranking and I get a P1351 code (ignition control circuit high voltage). After printing out the schematic and tracing things through four pages it looks like the ignition signal routes from the VCM to the EGR, crank position sensor, ignition module, coil, and looks like the pulse for the injectors. So what I thought was a fuel problem not seems to be electronic so I guess I’ll start pulling sensors and doing the good old Ohm check looking for a sensor that was going out and is now officially dead, check connections, double check my grounds, then hooking up jumper wires looking for the bad section of wiring. Does all of this sound like I’m on the right track? Anybody seen this before? Common problems I should be aware of? I need to go back out and make sure I still have spark before jumping all over this but I bet $100 I still have pretty blue spark. Thanks for any and all replies.

 

That era Tahoe is infamous for the spider injection going bad. That sounds like what is happening to yours. I had a 1996 do the same thing and I could cycle the key a few times and it would get enough fuel to start. Upon inspection one of the arms of the spider injection was cracked and puddling fuel inside the intake. If you have never had one apart - those years Vortec have a single fuel injector with 8 plastic arms - one going to each cylinder (hence the name spider injection). The plastic is prone to get brittle and crack so instead of all the fuel getting to the cylinder some will leak out and puddle inside the intake and make for hard starts or no start and rough idling/running. It's a good idea to do it along with new lower intake gaskets b/c they will also fail after 100K or so. I have done quite a few of them! Hope this helps.