I have a 95 GMC Jimmy wit the 4.3 vortec. Anyway it got me out to college (a 42 mile drive) just fine, though it would sputter and RPMs would flutter 100 over or under where it was supposed to be, it did this the other day as well and it would not start, I let it sit for a few minutes and it was fine. Anyway when I got out to it to leave from school it wouldn't start. It would crank just fine, just no ignition. I checked the plugs, they were sparking blue. I heard the fuel pump, but I tested it at the nozzle behind the manifold and the pressure was low, it just trickled out. While at the college I changed the pump. It started once I got it back together but only for a second then it died and would not start again. I tested the pressure just after the fuel filter and it was 70psi, but at the valve nozzle thing it still only trickled out. I don't know whats going on, please Help!!

 

Did you change the fuel filter?

 

^^^VERY important to do so.
I don't know about the rest of you guys,
but I change mine every 6 months or so.
Never fails either, always some black crap
that comes out of the filters too.
Must be all of that high dollar gooood gasoline they
make nowadays.

 

Yes, of course. As well as the strainer. I connected the pressure tester directly to the out port on the filter, so its not that.

 

New fuel pump, strainer, and filter. PSI at manifold plug is 65. Has blue spark and spark plugs are clean. Every other time I try and start it one or two of the cylinders will fire and that is it.