The subject is a 2000 Chevy Blazer 4.3L CSEFI.

I have verified that I have fire at the plugs. No codes have been set. However, it chooses when it wants to crank if you will. If I shotgun a little gas into the throttle body it cranks right up. In finding this out, I then hooked a fuel pressure gauge to the shrader valve test port and read 52-54psi with key on and not cranking over. When it cranks it stay around 60-64 psi. I changed the filter out (which was plugged up pretty good by the way) and it fired up fine until it set over night. Also, when it does crank and runs a few minutes (regardless of the engine temp.) it will always crank again unless it sets for 3 or more hours. When you listen near throttle body it sounds like a stopped up pump purging when you turn the key off and fuel pump goes off. Then a second later there is a click. Here is my question: is this a weak fuel pump or a fuel pressure regulator problem? And should I connect the pressure gauge behind the fuel filter or will this be nearly the same as at the shrader valve? In other words, is the fuel routed as so: gas tank, pump, filter, shrader test valve, etc. or gas tank, pump, filter, spider assy, shrader test valve, etc? Any help will be greatly appreciated. P.S. I know this doesn't amount to much, but fuel pump was replaced 4 years ago.

 

Follow through the steps to help find the problem source:

96+ Fuel System Diagnosis

 

The system runs as follows; tank --> pump --> filter -->test port -->SCFI spider --> FPR --> return line back to tank.

Testing pressure at the test port gives you the pressure that the SCFI spider sees. One piece of information that seems to be missing is the leak down. The pressure should remain above 50psi 10 minutes after the pump shuts off and should be greater than 55psi at all times. A low pressure or excessive leak down could be caused by a problem with the FPR and/or the pump itself. The only way to test for which is to remove the filter & adapt the gauge to the line from the pump to the filter. This will isolate the pump. If you still do not see >55psi that holds >50psi for 10 minutes after the pump shuts off, the pump is bad.

 

That's what I was thinking, but where can i round up the the fuel cutoff (J42964-1)? Can I round up some compression fittings and a cutoff and attach it that way (like lp and nat gas fittings from lowe's) or is the said part required due it being mechanically more complex (sorry for the technical words)?

Thanks for the quick responses. I appreciate it greatly.

 

The easiest way I have seen people do it is to get a fuel injection line repair kit which includes the female quick connect fitting. From that, a hose barb to 1/4" or 3/8" NPT. From the NPT to the 7/16-20 JIC male fitting that matches the fuel pressure test port up on the engine. This can be expensive. I got lucky and found the proper fitting that matches the IN port on the filter on one end and NPT on the other. Then I just bought the proper JIC to NPT fitting.

 

Ok. I think I got the adapter figured out. For future reference to other viewers here is how I adapted it. I went to lowe's and took my gauge and a fuel filter I had laying around. Turns out, after some "backwoods" engineering I found 4 fittings that combined will adapt the gauge to the fuel line. It cost me a total of $11.81 where I live. They are as follows (from gauge side to fuel line): 1/4" flare x 1/4" MIP > 3/8" MIP x 1/4" FIP (A.K.A. a Bushing) > 3/8" flare x 3/8" FIP (A.K.A. a coupling) > 3/8" flare to flare swivel. There should be no noticeable variation in pressure, than if the fuel line went straight into the gauge using no fittings (minus the obvious loss due to length, but this will be so minor the gauge reading will not show any difference. Plus, its a closed system... theoretically or should be -for all you technical folks out there).