So, I have read through a a bunch of these hard/no start threads and tried a few things and I still can't figure out whats going on with my truck. Its a 90 Pickup with the 3VZE. I've owned it for almost 5 years and since I bought it it would always take a few cranks then fire up and run like a top. This past winter I noticed a few times it would take a few extra cranks when it was super cold (20ish and below) and thought nothing of it given how cold it was. Well starting about 2 or so months ago, I started running into issues where it just wouldn't start, it will just crank and crank. Didn't seem to matter if it was 40 or 90 outside. Sometimes I found that if I jumped the terminals and let the fuel pump run for a few seconds, it would start about 60% of the time. Other times it would just crank. Ran some seafoam through it and that seemed to help initially with starting and it ran smoother, but no start issue came back a few weeks later.

It is also completely intermittent, try and go start it and it fires right up no issue. Drive it around running errands and start and stop it a few times, no issues. Next morning it wont start. Try later in the day, might start but runs rough, but smooths out after running. Next time I need to drive it, it will start no issue. It's left me stranded at work a few times and I either got it started after like 30 min of trying or had to call my wife to come pick me up. It wouldn't start the other day for her at the gas station after filling it up. She had a friend come pick her up, I stopped by a few hours later and it fired no issue.

Another thing I've noticed is that when I unscrew the gas cap, I get a large hiss of vacuum pressure once the cap it off. It also seems to have a better chance of starting if keep the fuel tank above 50% full, but even then its a coin flip.

So I have checked all fuse's and vacuum lines. Spark plugs and fuel filter were both changed last fall. Tried disconnecting the cold start injector when it wasn't starting and that didn't seem to have any effect on anything.

Any ideas?

 

no one has any hints or thoughts?

 

I think my next step would be to check fuel pressure. See if it's low or naught when having the no-start issue.

 

Have you checked ignition timing? Have you checked for stored codes? (Checking the fuel pressure on no-start would eliminate a lot of possibilities. Carrying your timing light will make it easy to check for no-spark).

The pressure (not vacuum) in the tank is normal. On a warm day, the fuel vapors increase the pressure. Especially with low fuel (more room). Given a while, those vapors will be adsorbed by the EVAP canister, but you pulled the gas cap before it could catch up.