Initial scan, hunting idle

[CNCguy]

We use new 00+ Delco regulators to insure long life. That's why I was wondering what was going on.

[86FieroSEv6]

Damn if that doesn't look like a leaking or weepy injector . . . . .

[SappySE107]

I use a new 94-99 base.

[Weatheralls Auto]

Damn if that doesn't look like a leaking or weepy injector . . . . .

Hmm, very possible, I really expected to see this run lean but it seems to be rich.
The Racetronix Walbro pump doesnt have a check valve so pressure leaks down as soon as pumps turned off,
think I will pull the rail and check for leaks next.

[Weatheralls Auto]

checked injectors, none weeping and balance test is good.
Still, Vaccum does not change fuel pressure, and when shutting off I loose pressure instantly.
If I pinch return line Pressure holds. Looks like a bad FPR, went to order a new delco today to check, Canadian price is $112, nuts!!!!!!!!!!
And our dollar is above par right now.

[CNCguy]

Double ouch... so much for the Delco regulators being the best choice for reliability. And that price sucks as you can get one here for about half of that.

[SappySE107]

If it holds vacuum, its not a bad FPR. Try tuning it instead.

[Weatheralls Auto]

If it holds vacuum, its not a bad FPR. Try tuning it instead.

Tuning? I do not see how that will effect my fuel pressure lol.
The AFPR does not hold vacuum, or my Vacuum pump is leaking.

I do have it working better now, I removed the screw completely, and started engine.
about 23 psi, when shut off it held the 23 psi as well.
as soon as I started to adjust the screw pressure dropped to 0 (not running)
Started back up without vacuum and set to 55 psi, plug in vacuum line and it dropped to 44 psi.
So this part is now working, thinking maybe plunger was jammed somehow and this straightened it out?

However, as soon as I shut off vehicle, pressure drops to 0. If I pinch return line it holds so the regulator is not holding the pressure
when shut off.

Is this just a characteristic of these I have to live with? (which I can) or is it faulty?

[SappySE107]

I didn't say it would affect your fuel pressure. I said the fuel pressure is not causing your idle RPM problem (with it not changing on vacuum). The regulator has nothing to do with the fuel pressure dropping on key off. That is your fuel pump/check valve. Tuning would solve ALL your problems, but I am not going to keep telling you this. You can replace parts until the tune falls in line I guess, if that ever happens.

[Weatheralls Auto]

I understand now you mean tune for hunting idle. (should have started new thread I guess)
However, it would be pointless to tune with the incorrect pressure, would it not?
I now have the correct pressure so tuning is next step. ( I was tuning and getting very rich reading, now seems to be much more stable)

I initially thought the fuel pressure dropping off was the check valve in the pump (or lack there of) however, why would pressure hold if I pinch the return line? or if I lower pressure by removing the screw?

I am not replacing parts, tuning would only mask a fuel pressure problem would it not?

[Weatheralls Auto]

Oh, I should add the hunting idle is also now gone.

[SappySE107]

With a sealed system, you can only vent to the tank and the return. Like putting a straw in a glass, putting your finger over the top, and pulling it out. No leaks, till you release the top.

You are talking about a pressure that is set at idle and increases slightly with higher loads. Not all systems use this so you can most certainly tune with static or rising rate fuel pressure. It is when the pressure drops from a clogged filter or faulty pump that you cannot tune it.

[86FieroSEv6]

Dude, that is a bogus regulator. I'd cut a few lawns for the money to replace it.

[Weatheralls Auto]

To let EVERYONE know though, Mark at TCE saw this thread and immediately said he would replace it.
I was not 100% sure if it was causing an issue so I was still testing.

TCE stands by their product for sure. I dont want to have him ship me a knew one if its not an issue.


Sappy, that make sence about the straw, just curious on why it would hold pressure if I remove the set screw completely?

Think I may just get a new one test it and see, then put the TCE cap on.

[Weatheralls Auto]

Well I got around to putting a Stock 43.5 psi regulator on today, fuel pressure now holds when vehicle shut off.
So as I suspected this was causing my headaches.
I took it one step at a time as so much was done at one time,
2.4 to 3500 engine, Stock to Racetronix fuel pump etc etc so wanted to verify.