Turns out I don't have the correct size line wrench for the fuel filter and line nuts...so I couldnt do the pressure test today. Will do it Saturday AM before starting a few part swaps. I did check wiring and connections, all clean and good, and I have good power going to fuel pump...car still didnt start though.


So, just so I'm ready for Saturday...what are my possible issues here? I'm going to do the fuel pressure test before the fuel filter, but if that comes back:

1) same pressure as in the engine bay, does that indicate ignition or air issue then?

2) higher pressure than in engine bay - engine internal leak...but which parts? Just tear down and check it out? (either FPR, fuel lines, or Injectors?)


Just trying to get as much info so I can be productive on Saturday.

 

You should get a higher reading at the filter, the FPR is no longer in play, so you'll actual max pump pressure. That is, if the filter isn't restricted and assuming you're connecting to the output. When I checked mine I connected my gauge to the outlet on the filter after disconnecting the plastic line. Your basic fuel line hose isn't rated for the pressures so I recommend key on for no more a few seconds and double clamp it. You did change the filter with the pump, right? A restricted filter will make for hard starts too.

 

Ah ok that makes sense. No worries about the hose...the pressure gauge I have came in a whole "Fuel Pump Diagnostic Kit" and includes an adapter for late model GM fuel filters...its in there for the TBI engines that apparently don't have a test port in the engine.

Anyhow, yes I did change the filter with the pump, but that was a while ago. If I get higher pressure at the pump then I'll try replacing fuel filter first, then move on.

 

My gauge is from harbor freight. The open piece of fuel line that came with it was meant for cars with carburetors and 7psi pumps, heh.

 

So from what Ive been reading..

If the fuel pump pressure is good, I need to swap the fuel filter, and then try reading at the engine. If pressure is good but still no start, I need to look at either crank/camshaft sensors, starter, or ignition system.

If pressure at fuel pump is too low, I need to replace fuel pump.

I'll post the numbers from the pressure test tomorrow AM

 

Ok just finished testing fuel pressure at pump before filter. I hooked it up with the inline adapter for TBI engines...worked great...except I got the exact same results...then I realized...ITS INLINE...so it was exactly the same test as in the engine bay. So I disconnected the fuel line and spent like 40 minutes trying to effectively block the other end of the fuel line adapter.

So I didnt have a great seal, but it held up to 60 psi then it started leaking at my blockage and the pressure slowly faded back down. Based on that, I'm really thinking that it IS NOT a fuel pump issue (the pressure would have continued climbing had my blockage held), or really a fuel system issue I'm dealing with.

Now I'm considering the cam and crank shaft position sensors as well as the starter. Im going to try pulling a few spark plugs and see how they look as well.

Will update soon.

 

FIXED.

Got the engine started, drove around, turned it off, gave it some time, restarted, started up fine.

Problem was:


The top plug was cylinder 4, cracked insulator and arc marking on the surrounding heat shield. Bottom plug was cylinder 1... it was still in one piece when I pulled the spark plug boot, but in backing the plug out it snapped. Wasnt hard to back out or anything, it was ready to snap. Also had arc marks around the heat shield.

I'm wondering if my lack of wheel well guards (long since broken off) is allowing water/mud to get up onto the hot spark plugs and is fatiguing the insulators?