Electrical Gremlins

[adsm08]

Not sure how to respond, not what I see in voltage circuits I test, but I see what you are saying in your test

So I will stand corrected, but just came back from my 1994 after testing OBD slot and it still shows the 14v with engine running and meter grounded

I went and checked this on my Ranger, which is wired up with all the stuff from a 94 Explorer. KOER at the fuel pump relay pin on the OBD slot I have .334 volts.

The only thing I can think of to make your readings make sense is if you are testing with the negative lead on the OBD plug's pin, and the meter's positive on the B+ terminal.

 

[aball4620]

So much to respond to here.... Imma do some tests and then get back to you guys See if I can confirm all of the "suppose to's" and maybe find something that is tripping it up. What I do know for sure is that pin 22 is seeing a significant drop - certainly more load than a relay would apply.

 

[RonD]

Yes, for sure it would read 14v using positive to OBD slot with KOER because pin22 is grounded at that time

I used a different meter and did see the voltage drop under 1 volt, KOER , using ground reference, and 14v using positive reference

 

[aball4620]

Well, new ECM is on the way. Still haven't found the source of the fuel pressure loss. I've swapped out for a different set of injectors and a fuel pressure regulator with no changes. I'm still maxing out at about 36 psi priming the fuel pump a few times, idling around 26-28 and it seems to idle just fine after warming up. After a couple hours I'm right around 30-32 psi, after 24 hours I'm usually down around 10. After a couple days it does drop to zero.

Had to pick up an new compression gauge as nobody is currently loaning them out. I knew that my engine was getting worn when I did the head gasket and the compression readings show that, but should still be running better than it is. 1 - 138/162, 2 - 143/155, 3 - 136/164, 4 - 144/155, 5 - 135/144, 6 - 123/135. Fresh codes or lack thereof reveal nothing. May end up warrantying the new high pressure pump as it seems that check valve is about the only piece that could be allowing a pressure drop at this point.

I have noticed that the idle seems to really smooth out when the engine is warm and I put it in gear. Vacuum pressure has seemed to hold steady (does fluctuate with a hunting idle) at 18-19 psi. In gear is just moving into and out of the garage - put it on the street and it barely wants to go. But is definitely a smoother idle nonetheless. Any other ideas while I want for the computer to ship?

 

[aball4620]

For an update - a new fuel pressure regulator seemed to smooth out the idle a little. At least now I can pull the vacuum hose and see the fuel pressure increase while it is running. Still low around 29 when running but more consistent.

Replaced the ECU with a rebuild cardone and....... nothing. Absolutely no change. I'm at such a loss here. I guess it is time to start going after all of the grounds? Is there one overlooked ground that commonly causes problems? I also ran through another obd1 scan and there are no codes whatsoever at this point.