I did end up finding the MFI spider...and buying one.

When I got into the upper intake area I found signs that several of the fuel injector o-rings ~had been~ leaking (moistness, gumminess, tarnish). But, for some reason, they did not visibly leak when I had everything opened up. I pulled each fuel injector out of its hole, while having someone cycle the fuel pump for me (oncefor each fuel injector). None of the poppet nozzles appeared to be leaking...nor did the FPR.

As I said before, I just had the fuel pump replaced about 6 months ago. So, I started thinking about what else could be going on. I don't know enough about the metering body, as a system, to be sure. But, I thought that fuel pressure could be bleeding to the return line when it shouldn't be. It would havebeen nice to have had caps for the fuel lines (before the fuel rail) to isolate and test before themetering body...but, no gots.

Anyway, partly because I was there, with everything open (and the MFI spider was only a couple hundred dollars) I did install the MFI spider. Before putting the upper intake plenum back on, I did replace the connections, pressurize the fuel lines, and test.

What I found was that fuel pressure was still bleeding off, as steadily as before, but much more slowly than before. Now, it fades from about 60 psi to about 20 psi in one minute...and then hovers around 20 psi for about 2-3 minutes before falling the rest of the way to zero psi. There wasn't much else I could do in the area I was working in. So, I put everythng back together and ran the vehcile.

Some things are better...but, the truck's still not right. The vehicle acclerates more smoothly and quickly...and that's about all I earned for a days work. It still idles roughly...and starts like crap. I still need (or at least want) to change the plugs. I haven't checked them yet (I know I should have)...but, I estimate the excess fuel they were getting gummed them up. I suppose that might help the idle...not sure.

It's dissapointing to think thatI could be having problems because of the fuel pump check valve 6 months after having it put in...but, I'm thinking that that's my next target.

Any feedback would be appreciated!

Icarus

 

I had a look at a friends factory service manual for his '95 (I do not have one for my vehicle). I imagined that some things may be similar enough to at least give me an idea of other things to be looking for, or at.

In the troubleshooting section for hard cold weather starting, there is some information on how the fuel pump is wired from (or through) the oil pressure sensor. The manual outlines that when the fuel pump relay fails (or becomes intermittant), a fuel pump start signal will come from the oil pressure sensor BUT only when proper oil pressure is achieved. Apparently, this was done to prevent the fuel pump relay from being a single point failure.This set of circumstances explains the difficulty in cold weather, as proper oil pressure is more difficult and time consuming to achieve.

Could this bethe problem in my vehicle? Is this configuration still used in 2000?

If this is a problem for me, or anyone else, I'm suprised it would go undetected. I would think the ECM would be aware that the fuel pumprelay was no longer generating the start signal and post a fault.

Thoughts?