Maeson Yosick

I'm not exactly sure how to test and what I'm testing for if anyone has a link or something info that will help that would be nice.

scope103

2. You'll need a gauge and a way to connect it. The easiest way is a gauge built for that purpose, like This one comes with the banjo-schraeder adapter that you will need. You'll want to leave the adapter in place; if you remove it and replace the original bolt, you'll need new crush washers.
3. Here's a picture of one installed: https://www.yotatech.com/forums/f116.../#post52330847
4. What should the pressure be? All answers are found in The Good Book: http://web.archive.org/web/201003261...87fuelpump.pdf

(for completeness, several on this forum have "rolled their own" pressure gauge, and permanently installed it. You can find their writeups by searching. On the 22re, it is probably more common to attach your gauge through the CSI rather than the FPR; that takes a 10mm banjo rather than the 12mm on the FPR.)

1. Why are you testing fuel pressure?

Maeson Yosick

I'm testing fuel pressure because my truck doesn't run and I think that could be a problem, the fuel pump work and I just replaced the filter and the AFM unit, checked all fuses they're good, replaced COR that should be good, I'm just kinda lost on what to do to fix it ha.

scope103

Doesn't run at all?
Before you go to the effort of testing the fuel pressure, you could check flow. Replace the fuel return line from the FPR with a piece of clear vinyl 6mm (1/4") tubing to a suitable container. Run the pump by jumpering FP to B+. Then do it again at idle. On my '94, I got about 1/2 liter/minute at idle.

If your pump isn't running, or produces less pressure than required in the FSM, or if your filter is blocked, you won't get any flow out. But if the FPR has failed (so that it doesn't "back up" enough pressure in the rail), you'll get plenty of flow out anyway. So adequate flow is only 1/2 of the equation, but it's the more important part.

Maeson Yosick

Correct, doesn't run at all I passed the relays and such so I know the fuel pump is working I hear it work but then the truck won't turn over.

scope103

"won't turn over." To me (and most people) that means it Won't. Turn. Over. I'm guessing it DOES turn over, with gusto, when you turn the key to start. It just doesn't FIRE or RUN.

Just because you passed the relays doesn't mean fuel is getting anywhere. (Which is why you want to check fuel pressure -- which is smart diagnosing.) Checking the fuel pressure is the acid test for, well, fuel pressure. But you can save a few bucks by checking for flow first. If you're not getting flow out of the FPR, it's pointless to check the fuel pressure until that's fixed. Something else is wrong.

But if you have fuel flow out, checking for pressure will confirm the FPR is good.

Maeson Yosick

OK I will get some clear vinyl tube and test the fpr return line for flow, from my understanding if there's no flow the fpr is broken if there is flow it works and something else is wrong with my truck. There for I would continue on and buy a gauge and check the pressure?

scope103

Well, I imagine there might be a failure mode of the FPR where it blocked all flow, but that would be unusual.

The way it works is the pump runs at full blast all the time. The FPR measures the pressure in the rail, and "returns" whatever flow would make the pressure higher than needed. With engine off, it's returning all the flow. At idle, returning most of the flow. At WOT, the injectors are taking a lot of fuel, and much less can be returned by the FPR.

If your pump isn't running, or if the filter is blocked, or if the pump is just so weak that it can't reach 33psi in the rail, then nothing would come out of the FPR. No flow from the return of the FPR usually indicates a problem toward the pump, not in the FPR.

Maeson Yosick

My truck doesn't run so I turned it to the "on" position so the pump runs, I put a clear piece of tubing on the return line then let the pump run and nothing, but when i took off the return line some fuel still leaked out the line and on my hand.

scope103

Time to RTFM. The fuel pump is NOT supposed to run with just key-on. (It runs with the key to start, then once air flow starts the FC switch in the VAF takes over.) To run the pump for testing you just use the procedure in the Manual page I cited to. (The SST is the same one you use to check for codes.)

Maeson Yosick

I jumped the diagnostics box with a jumper from Fc-B+ turn the key one click(nothing) turn the key to start(I hear the pump running). Let pump run for a minute or so and nothing came out of FPR. Next step replace FPR? Or any other tests I can do to narrow down the problem?

scope103

First, I'd find out why the pump is not running with the jumper. Fp to B+ just bypasses the COR. It's actually fairly easy to get the wrong hole in the diagnostic connector. Use your multimeter; you should have battery voltage on B+ with key-on. With key off, check resistance to ground at Fp (the resistance is single-digit ohms, so it will look a lot like a dead short). If Fp was REALLY shorted to ground, you'd get fireworks connecting battery voltage to it.

I can't hear my pump with key to start; the starter makes too much noise. But I suppose you could move to the back and put your ear close to the tank and hear it. I think it's VERY unlikely to be a bad FPR; if it was stuck closed you'd have too MUCH pressure in the rail. The truck would start, but run like poop.

So I think your pump is not pumping. Fuel pressure test is next, but if you want to defer the $50 for the tool, you can take one more step. You can loosen the banjo bolt below the FPR, start the pump (CAREFUL!) and look for a vigorous spray of fuel. I usually advise against loosening any pressurized fuel connections, because that pair of crush washers MUST be replaced every time. But since your plan it to attach a fuel pressure gauge there, you were headed in that direction anyway. (I always got my crush washers from the dealer. They're not expensive online, but shipping will get you. Or, see this discussion: https://www.yotatech.com/forums/f116...s-made-307567/)