Ok, while checking fuel pressure on 2001 Blazer that will not start (tries to after several "tries" but then acts like it is not getting fuel) when key is turned on (not started because engine will not start) fuel pressure goes up to 60 psi, when fuel pump shuts off after prime the pressure immediately drops to 55 psi. Should it do this? I thought that it should hold pressure longer than that.

 

It shouldn't drop immediately. If it drops more than 5 psi in 10 minutes you have a problem. Either the filter is plugged, the regulator is bad or injectors are bad. How far does it drop in 10 minutes?

 

Will check that when I get home and will post results. Thanks!

 

While waiting for my husband to get home so we could check the pressure 10 minutes after priming, I decided just to try it. Started right up!!!! Still starting. Had a slight problem starting if i primed the pump first before turning the key completely over. I DON'T GET IT!!!!!

 

OK, this is what is happening. If i let the pump prime before trying to turn over engine, it will not start. If i just turn the key all the way to start the engine without letting the pump prime, it starts right up. Any ideas

 

Is it throwing any codes? Black smoke out of the tailpipe?

 

No codes, no black smoke. Someone suggested may be a leaking diaphragm on fuel pressure regulator. They said that by priming it that the leak could flood the engine so it will not start. That does make sense. I will pull the vacuum hose tomorrow after priming the pump and see if it has gas in it.

 

Umm.. there's nothing to pull. It's not a fuel rail system, and the regulator is inside the plenum. You'd have to pull the upper intake to check it. Since you've already seen the leakdown is quick, it's probably a good bet to look.

 

Did pressure test. Starts now when primed first. Actually starting great with and without priming. Ok, started it up, got up to 60 psi, while running around 50 - 55 psi. After turning it off, stayed at 50 psi and held steady for at least 10 minutes. Checked it again after about an hour and the pressure has increased to around 54 psi. Guess it is not leaking. Did put Marvel Mystery oil in it Monday. May have had a blockage somewhere and marvel took care of it. Don't exactly know, just know that it is holding pressure and starting great and seems to be running better. We will see!

 

The test needs to be done with key on, engine off. Post back those numbers.