On your 1995, dead head pressure at the filter, (or pump, doesn't matter) should be 73psi to 108psi while the pump is running. It must hold above 50psi for at least 10 minutes after the pump shuts off.

There should be battery voltage on the grey wire at the pump module for ~2 seconds when the ignition is initially turned to the RUN position, (engine off). Voltage should drop to zero after the ~2 second time frame.

The black wire at the fuel pump module connector must show less than 5 ohms resistance to ground at all times.

 

Just checked my ground and voltage. Both are good. 13 volts when it should be there. Ground is fantastic. I'll have to get some fittings to check at the filter. I was having a hard time getting at the pump. I'm tired of crawling around underneath the thing!

Maybe it's a clogged filter. But that doesn't explain why it won't hold pressure.

 

This thing has me confused. I'm getting no pressure anywhere. At the pump, at the filter, or at the test port. I can hear the pump running. It's very loud. Much louder than the one I replaced. I even jumped the pump and let it run for several seconds, and it still never built pressure. I just don't get it. No leaks anywhere, and the pump is obviously running. I even tried pinching off the return line with vise grips, and it still never built pressure.

I made sure there was gas in the tank, too. I put five gallons back in after I got the tank up. I guess I'll pull the plenum off. Again. Although there wasn't any leaks last week when I tried a new regulator.




edit: pulled off plenum, no leaks while pump is running. I even pulled out the individual poppets to make sure one wasn't stuck open, or something.

I'm beginning to doubt the accuracy of my gauge. It never moves off zero, despite there being pressure at the test port when I attach or detach the fitting for the gauge. But it still doesn't start.



edit again: resistance across the injector is 1.7 ohms, which i read on another thread is correct. Also, there is 12.5 volts across the connector when the key is turned on. While cranking, though, the voltage drops to about 8. Is this normal? I'm running out of things to check.

 

hey the last pump i did i put the new pump in, and wife drove it a couple days, hit a speed bump and it died, towed it home, had pump sound but no fuel pressure, took pump out of tank, and it happed to be that plastic flex tube from the pump itself to the top plate of the fuel pump, had a wimpy crimp and it popped off so it was just pumping right back into the tank.

pushed it back togeather and squeezed the crimp more, and sold the new pump and bought another new one. and was good to go, i think the pump would have worked fine again tho, but already had the new pump.

 

Yup, if the pump is running but there's no pressure at the filter, that accordian plastic flex line probably came off, has a hole in it, or is kinked. Pull the fuel line off at the fuel filter and activate the pump, see if it squirts. If it does, make sure the tester is depressing the schrader valve.

 

I think the gauge is bad. I can depress the test port schrader valve, and fuel squirts out. But the gauge never comes off zero.

Anyway, father in law came over, and we sprayed some starting fluid into the intake, and it fired right up. Kept running until I turned it off fifteen minutes later. I let it sit for a few minutes, and it fired back up on its own, although it did seem to take a split second longer to lite off than I'm used to. I'll let it sit for an hour or so, and see if it will start on its own again.

It revs great in park, and idles fine. Driving though, it acts like it's running out of gas. Give it more than a crack of throttle, and it falls on its face and sputters. I got up to around 40 mph, and it gave me P0131, O2 sensor voltage low input. Does this indicate a lean condition? I would think the fuel filter is clogged, but I checked that already today. I might try to return the gauge, and rent one from a different place on Monday.

 

P0131 indicates low voltage from B1S1, (pre- catalyst sensor on driver side). Low fuel pressure could set it. Usually both B1S1 and B2S1 will set simultaneously but if they are not both calibrated identically, it's entirely possible for only one to set a DTC. Everything you're describing points to low fuel pressure. Might want to rent a pressure tester and check pressure & leakdown.

The voltage drop that you posted back in post #13 sounds screwy. Here's an article that explains how to test for it: Voltage Drop Testing

Check it at the injector, see what it reads.

 

I only have two 02 sensors, one in front of the the cat and one after it. I'm thinking low pressure, also. The gauge I rented seems to have quit on me. It never shows pressure, even though I can manipulate the schrader and fuel sprays out. Ill try a different one Monday. I just can't imagine a new Delco pump is bad out of the box, but stranger things have happened. I've already tried a new regulator, and that didn't do anything, either.

 

Oops, 95 with OBD1.5
I see DTC's starting with "P" and immediately think OBDII.... gotta slow down

 

It really seems more like an OBD 1.75. The number of 02s, and injection system doesn't seem to go with the location of the computer (passenger inner fender), obd 2 port, and the fact that my obd 2 only cheapo code scanner reading codes from it. But the inspection place couldn't get their machine to read it, so it got the obd 1 inspection done to it.


After a two hour wait, I expected it to not want to start, but it did; decently quickly, too. Still no power, and all but stalls out at more than ~10% throttle, but I was able to nurse it to 55 mph earlier.

I thought it might have been a TPS issue (I'm grasping at straws, here) but I manipulated the throttle while viewing live data on my scanner, and the TPS smoothly transitioned from 0-100.

I'm thinking it's got to be fuel pressure. I need a different gauge, and maybe I could figure something out. Until I can get repeatable numbers, this is all just subjective, I know.