I have a 2001 4.3 vortec, 4 door, automatic with 4 wheel drive. I can try to crank it but it will turn over and sometimes hit but not actually run. I have to keep trying it or either cut the key off then on for a few seconds THEN try to crank it and it most of the time will crank & run. Here lately it's got to where it will almost run the battery down trying to crank it even if I cut it of & on before I crank it. When it does crank it will run fine, no misses, no hesitations, Etc. As long as it doesn't sit for a long period of time it will MOST of the time crank back up with little trouble. I don't have a pressure gauge ( can't find anyone who does) and don't want to really buy one ($40+) So any ideas or suggestions I could do? I've depressed the valve in the test port with it off and very little fuel comes out and I've depressed it while running and it shoots out & actually caused the engine to sound like it tried to die. I've been told its' the fuel pump, but looking at the diagnosis post on here it could possibly be my check valve, the regulator or even the injectors. I DEFINITELY am not taking it to a dealer to pay $100 + just for them to say what's wrong with it. Anything in particular I could try?

Oh and I replaced the fuel filter too before but it didn't really help alot, even took it back off the other day and seemed ok. but still has the same problem.

 

If I understand correctly, your engine will crank okay, but not start, right?Without a pressure reading you can't tell squat about the fuel system.
96+ Fuel System Diagnosis
98+ No-Start - Engine Cranks OK

 

The engine turns over fine ALL the time, just hard to start. I ran across a pressure gauge (not fuel pressure test gauge) that had up to 120 PSI. I disconnected the line from the tank from the filter to start there. I rigged it to the line to see IF the pump was pumping. I got someone to turn the key on and got about 55psi from the pump. So that means it's pumping so what should I check next? Where is the regulator located? How could I check the injectors?

 

55psi when dead heading the pump is kind of low, but not too low. Did you happen to watch to see if the pressure bleeds off after the pump shuts down? Next, connect the gauge to the fuel pressure test port on top of the engine and see if you can duplicate your results previously observed at the fuel filter location.

 

Well 55psi is an approximation due to the way I had to hook up the gauge. I should have kept the old filter and could have made me an adapter to hook up better. As for the bleed off, I'm unsure about it because of the way I had it all hooked up to the line from the tank. I need to refine my connection and can get better readings. But at least its a start.

My next plan is to try the test connection at the engine you mentioned.

I forgot to mention, it did set up for a while before I got it and ran a little ruff at first, the day I got it but I put some premium gas and some sea foam in it and its been running great until about 3 or 4 months ago when this started happening.

 

i had pretty much the same prblem. turned out to be the fuel pump. went to the U-PULIT YARD. and put a used one in and no problems since..

 

Where is the fuel pressure regulator located?

 

I got the gauge (not a regular fuel test gauge but a 120 psi range gauge) hooked up on the fuel rail and turned the key on but pressure only went up a little bit, turned key off then back on about 4 more times and pressure kept progressively getting higher till it got to around 45 to 50 PSI. it cranked up and while running it was holding about 51 to 52 PSI, ran fine and smooth. let it set there idling while I was moving some stuff around to get ready to put it up on the ramps, everything still fine gauge still reading about 51 to 52 psi. Backed it up on the ramps and cut it off, pressure read about 47 psi. 2 minutes later pressure was about 38 psi, 10 minutes after cutting it off pressure was about 25 psi, 15 minutes after cutting it off pressure was below 15 psi. turned key back on 1 time and pressure jumped to about 52 psi and cranked up. held about 51 to 52 psi, revved engine slightly and pressure went to about 59 psi but back at idle it went back to 51 to 52 psi. I believe more than likely its the fuel pump, this is happening and fuel gauge in dash acts a little "weird" below 1/2 tank. I'm just making sure its the pump before spending the $$ and the time dropping the tank.

 

If you worked through all the steps in the first link in my reply post, you'll have the answer.

 

I looked through them BUT not every body has a scan tool or the other adapters it mentions. The information I posted is all i can do besides just start replacing stuff.