I have a 2002 stock everything original GMC Sierra, with a 4.3 Liter engine. I need help tracking down a starting issue. The truck back in December began having starting issues. Without warning from one day to the next, stopped starting up. It turns over and over but won’t start. Shot some starting fluid into the throttle body and nothing. Went back the next day, cranked right up. It will run for a month no issues, and again, without warning it won’t start.

We have taken it in to several shops but they can’t diagnose it, because it will start for them, because a day or so will pass by the time we can get it there. So far, we have had injectors cleaned, and fuel filters changed. The shop says fuel pressure is fine. Everything checks out once it’s running. We just can’t figure out why it will not start from one day to the next. But if you give it 24 hours, the truck will start, even without starting spray.

Has anyone here encountered something similar and if so, how did you fix it? Thank you so much in advance.