Intermittent starting problem

buddyo · February 4, 2020

2004 silverado 5.3L Z71 Ext. cab

Back in December I decided to get my rear main seal fixed. Took it to a reputable transmission shop that does this regularly. They replaced the seal and the cracked plate it sits in. They also replaced the camshaft sensor because it’s prone to leak. When I picked up my truck It took two tries to get started. Didn’t think too much about it but it did it several more times. It is an intermittent problem. Yeah, one of those. So I took it back to them and they replaced the new camshaft sensor with another new one. Still took two tries to start. They then put a camshaft sensor in that was a known good one out of another chevy truck but still didn’t solve the problem. Never had this problem before the seal fix. They suggested taking it to a local mechanic to see what he could find. This guy is known by everybody. He’s got more work than he can handle. He kept my truck for 6 weeks and I honestly think my problem was low on the totem pole. Anyway, I took it back because nothing was getting done. What I have done was remove the intake manifold and checked the camshaft sensor and the pigtail they installed and it gives ,using a short/open tester, a tone back to the black fuse/relay box. Put everything back together and connected fuel pressure gauge to rail and spark tester to #1 plug. Engine started on first try. FP=64psi and good spark. Tried later on and no fire on first attempt. Still had FP=64psi and spark. It always starts on 2nd try. This is baffling as hell and someone would make a friend for life with a cure.