Tbi fuel pressure gauge adapter

[RShrimp]

Yea, I recently went through AC hell because of a defective set of gauges.

 

[scott2093]

I guess I need a new set...Idk...
I can get fuel to come out of the adapter (after fuel filter install) if I push in the stem while koeo but it's more like a dribble. I can get fuel to come down the pressure release hose...not a crazy amount of stream though....... But I can't get the needle to move on the gauge....

That fitting in the hose end just rests in there with a rubber sleeve...I flipped the sleeve around and same thing...
hmm...
One of the pieces isn't working right... Truck runs fine enough so obviously has some pressure.....right?lol

hazard fraught maddox set only one close with tbi adapter to satiate my impatience... hmm.

 

[termite]

I guess I need a new set...Idk...
I can get fuel to come out of the adapter (after fuel filter install) if I push in the stem while koeo but it's more like a dribble. I can get fuel to come down the pressure release hose...not a crazy amount of stream though....... But I can't get the needle to move on the gauge....

That fitting in the hose end just rests in there with a rubber sleeve...I flipped the sleeve around and same thing...
hmm...
One of the pieces isn't working right... Truck runs fine enough so obviously has some pressure.....right?lol

hazard fraught maddox set only one close with tbi adapter to satiate my impatience... hmm.

Key on engine off, the fuel pump will only prime ~2 seconds unless you jump the proper wire.

 

[monsterwake]

I used the harbor freight one this past weekend. It came with the tbi adapter. I was scared to keep in on there though. It sounds like it is normal to do this.

 

[someotherguy]

I used the harbor freight one this past weekend. It came with the tbi adapter. I was scared to keep in on there though. It sounds like it is normal to do this.

Eh, with a few recent mentions of leaks, I'd go ahead and take it off. I used to advocate leaving it in place, but that was my experience years ago with a different brand of the same style fitting. With what's out there today - especially from HF - I wouldn't risk it.

Richard

 

[scott2093]

Key on engine off, the fuel pump will only prime ~2 seconds unless you jump the proper wire.

That makes sense....
Looks like the tbi adapter stem is identifying as a joystick and to get the hose to depress it is an exercise in futility... Now I remember why I took it out.... It was like roulette trying to get the gauge hooked up right.....

Is that valve replaceable in the tbi adapter?

Drove to HF and of course they showed 5 fuel pressure testers in stock but they couldn't find them. Only the deluxe kit which was 90 bones....no thanks....

 

[scott2093]

Is that valve replaceable in the tbi adapter?

apparently it is.
Does anyone know what I should look for to replace this? I'll try straightening the stem but replacing would be nice....I'll check my bicycle tire stash..lol

 

[termite]

apparently it is.
Does anyone know what I should look for to replace this? I'll try straightening the stem but replacing would be nice....

Definitely replaceable but I'm not sure where to source one from except manufacturer. Possibly you could use a tire core just for the testing and remove the adapter immediately afterwards? (Assuming threads and dimensions are the same, i doubt the seals on a tire core will withstand gasoline exposure for any extended period of time)

 

[scott2093]

Possibly you could use a tire core just for the testing and remove the adapter immediately afterwards?

worked.....

Still had to futz with the hose end for some reason. Just removed the gauge until I was sure fuel would come out....and when priming....
11.5+ psi....idling...

Is that ok pressure if right after fuel filter? I mean, these fuel regulators aren't like electronic regulators that need a minimum specified input higher than their outputs???

What's weird is I could see the needle jiggle here and there..
When I was at Autozone talking to the one young guy there who has a GMT400, he mentioned one issue with these trucks that not many people know of is that, some janky oil pressure senders can flake out and modulate the fuel pump. Made me think of this when I saw the needle do that....

idk.... got a new Delphi fuel pump but mine is behaving atm although it was making some sketchy noises last week.... not looking forward to swapping it but maybe better than being stuck on the interstate 100 miles from home when I take this truck oot in a couple of weeks...not sure what the margin of error is on this gauge...and that it's 10 years old....

 

[Schurkey]

worked...

Good.

11.5+ psi....idling...

Is that ok pressure if right after fuel filter?

OK pressure ANYWHERE on the supply side after the fuel filter. Easily within spec, although folks would prefer to be at the high-end of spec.

IF (big IF) you knew for certain that the filter was not restrictive, it'd be OK on the pump side of the filter...but that's hard to know in advance.

What's weird is I could see the needle jiggle here and there..
When I was at Autozone talking to the one young guy there who has a GMT400, he mentioned one issue with these trucks that not many people know of is that, some janky oil pressure senders can flake out and modulate the fuel pump. Made me think of this when I saw the needle do that.

You could REMOVE the wires from the oil pressure sending unit, and have no effect on the fuel pressure IF the fuel pump relay and wire harness were in good condition.

You could REMOVE the fuel pump relay and have no effect on the fuel pressure of an already-running engine if the oil pressure sending unit and wire harness were in good condition.

EITHER ONE can run the fuel pump if the other one fails. If the relay fails, there's no fuel-pump prime cycle, and the engine has to develop oil pressure before the pump runs...so if the relay fails, cranking time is extended. Once the engine runs, though, you wouldn't know the difference.

not sure what the margin of error is on this gauge...and that it's 10 years old....

Ideally, you'd test the gauge against another "known-good" gauge. Or two or three "suspected good" gauges, and hopefully they'd all agree.