Here's the latest on my 2000 GMC Jimmy with 137K miles on it. 4.3 Vortec, 4 door 4 W.D. This is strange,,discovered today,,after hooking up fuel pressure gauge to shrader valve, turn key to on,,check pressure, only reading around 44 psi,,,so turned key off,,,by the way, my fuel pressure gauge has a bleed off button on it, so as to relieve pressure or bleed the gas out of it, anyway, after seeing that low pressure reading, I push the bleed button on the gauge to relieve the gas and pressure and gauge went to 0 like it should. Then, I get back in and turn the key on again and went out and looked at the F.P. gauge and to my surprise, it was reading close to 60, so I get in and it started good. (Don't see any fuel leaks right off,,but am wondering if fuel filter could have small crack or a restriction of some sort,,,,or bad hook up, meaing threaded connections....Sooo....here is my theory, on all of this, I think what is happening is there may be some air getting into the fuel line and maybe I am having a "air pocket" situation here. Just a theory you understand...but...why is my pressure going to where it should to start by me just pushing the bleed button on the gauge, then hitting the key again to prime the pump and it jumps to the much desired 58 to 60 psi and then it starts. Am I missing something here? I am thinking that I need to take a hard look at the fuel filter and the connections there and look for maybe some blockage there, or could I have just a bad fuel filter from Advance? But...I don't see any fuel leakage under the Jimmy on that side, but it could be a very very small leak and me not noticing it. Am a lost here as to why this is happening. The fuel pump that is in there now came from Advance (Carquest), and was put in there b4 I bought it about 1.5 years ago. Not sure who did it or how good a job they did. I think if a better fuel pump had been put in, like a GM Delco OEM or better, then I would probably see more pressure than I am seeing @ 58 to 60. Now, also, when I send the 12 V. directly back to the fuel pump, via using the prime terminal on the fuse block with key off, they I GET A GOOD 62 PSI. I think the voltage must be a little lower at the fuel pump back at top of tank using the key turn on and going through the fuel pump relay and ignition sw. I have cleaned the fuel pump contacts and even switched it out, but no difference it made. also checked all fuses.
So...what do you guys think?,,am I getting some air in my fuel line, at the fuel filter or beyond? Very interested, me just bleeding the fuel pressure gauge and I get good pressure after that,,otherwise without doing that,,pressure sometimes in the no start condition, meaning, it just cranks and cranks, I only get around 44 psi with the F.P. gauge hooked to the shrarder value...I am leaving the F.P;. gauge hooked up all the time, (a little hard for me to hook it up), but I don't drive the Jimmy,,just sitting in my driveway during all these test.
Think next thing I will tackle is have new fuel filter put in and may extra attention to the hook up and connections there on in and out on the filter.
The Jimmy runs fine when running,,no problems with missing or anything,,runs great when running. all normal there. Have a good almost new battery,,720 CCA rating. All gauge readings inside are where they should be,,have replaced the crank sensor and oil pressure sensor, but not the Temp. sensor yet. also has new plugs and wires and cleaned MAS sensor and new air cleaner. Let me close by saying, that some time ago,,,I read a post on here where this guy said he was having a problem like mine and he said he would get out and go to the sharader valve and push in on it a little to let some gas out and get back in and then it would start...Sounds like is about what I am doing with the bleed button n my fuel pressure gauge.....Driving me nuts...

Nuff said..lets get this start problem with my 2000 Jimmy fixed..(I hope)

thanks in advance...

 

Hit enter after each paragraph so post isn't just a block - darn hard to keep track of while reading
I don't think your getting air
FPR or faulty pump, sticking check valve in the fuel pump as it was in my 4X4 RX7
Do the whole fuel pressure tests per sticky instead of throwing parts at it and beating head on the wall .....

 

Air in the fuel line is NOT the problem, guaranteed. Atmospheric pressure is ~14.7psi The only way air can enter the fuel line, is if fuel pressure drops below atmospheric pressure. IF there is any air in the fuel line, (for example, changing the fuel filter) it will immediately bleed out through the regulator when the pump is energized.

Try this: Connect your fuel pressure tester. Using the prime terminal and a jumper wire, energize the pump several times and watch the pressure each time you energize the pump. It MUST achieve the same pressure each time. Then do the same thing with the ignition switch. If the pressure changes, or it's erratic, it might be worthwhile checking voltage drop at the fuel pump ground connection, (top rear of the frame, driver side). Not fun to get to, kinda have to use the eyes in your fingers

 

*To the OP, you have posted this problem in multiple threads, which is against Forum rules. I have created this new, separate thread for you, so please keep all discussion concerning this problem confined to this thread.*

 

Help...Need help with tracing wire from fuse block (back side), , 2000 gmc jimmy 4.3 4WD. Anyone out there that might know the color of the wire coming from the bottom of the fuse block, (the fuel pump prime wire beside the fuse),, and where it might go after leaving fuse block..I already know it is supposed to go directly to the fuel pump, but need to get to it b4 it goes all the way to the back..(hope inside the cab,, maybe ignition switch?? Gonna try something off the wall, to prime my pump b4 starting with button on the inside....Thanks...