Fuel pressure regulator

[VR-4Galant767]

Here's the deal...... My boost guage is tapped in at the fuel pressure regulator, like many people do. At first, everything was fine, reading both vacuum and boost, then it appeared as if the guage was sticking, so I tried another guage that I had from my Talon. Both guages will read boost every once in a while and stick at -20, -10 and 0. I know for a fact that I am 15 pounds; the guage showed it when it was working. I then thought that it was the line - maybe it had a kink or something so I hooked the guage up right under the hood and got the same results. I had an extra FPR, so I hooked it up. guage worked great until I ran boost, then started "sticking" again. Has anyone had this problem before? If so let me know how you corrected the problem. Thanks

 

[Defiant]

Since you did the direct test, have the manufacturer replace the gauge. Or, change brands.

 

[Enigma_Man]

I've had two autometer gauges in a row act "sticky". Just have them replace it.

-Jesse

 

[VR-4Galant767]

I also have a Blitz turbo timer that reads boost, and it "sticks" just like the two autometer guages. I think it may be the vacuum set up, although the complete vacuum"circuit" (if you can call it that) is all correct for the fuel pressure solenoid and the regulator. I am puzzled. After installing the other regulator the guages stick at different points than before. Also, at about 3000 rpms when the turbo spools and start to build boost, (although I can't see it with no guage and all) the car feels sluggish and I notice that my A/F ration guage drops all the way to lean. this happens for about a fraction of a second and then the car pulls good and hard (which I am proud of). It worries me because I am running 510cc JDM injectors, a walbro 255 and running really rich. It is hard to tune because I need to lean things out, but with it dropping out so lean when boost kicks in I dont want to lean out too much. I don't have this problem 4500 and above.

Thanks for any help that you fellow DSM'ers can dish out.

 

[Omega]

I have a similar problem. If I hot start the car, both my boost and FP gauges don't work. I now get a FP solenoid code once and awhile. I have to pick one up to make sure though.

Does the gauge go back to normal after driving for a little bit?

 

[Enigma_Man]

Well, in that case, it's time to start narrowing down the problems.

Just to make sure, you have the stock fuel pressure regulator, and you aren't hooking up your boost gauge to a fuel pressure port on an aftermarket regulator, are you?

Anyway, to start, try hooking up the boost gauge directly to the intake manifold somewhere. See if it responds correctly that way. If it doesn't then your gauge is just bad. If it does respond correctly, then re hook it back up at the FPR. If it starts "sticking" again, replace the vacuum hose to the FPR/gauge, because it's possibly clogged / kinked / broken somehow.

-Jesse

 

[VR-4Galant767]

I am so glad to get some responses on this topic, due to the fact that I am puzzled. For one, the guage does go back to normal, but its like this. Start the car & everything is normal - needle on the boost guage guage drops down into vacuum, rev the engine and the needle will either read normal and go up to about zero, (1psi if i rev high) or it will stick between -18 and -10. It will rarely read boost, but when it does I see about 16psi and settles at 14. I will have to look into things this weekend.

Thanks for all the info.

Peace

 

[Omega]

If it never works properly, I would suggest checking your connections and then the gauge.

After you have done that come back here and report.

 

[VR-4Galant767]

Both guages operate the same, even my turbo timer which has a boost guage that is connected to the fuel pressure regulator reference. I have hooked the guages up under the hood and I still get the same result. What I am looking for here, is to find out if it my FPR or vacuum system. I got the entire car put finished two weeks ago and this is the only bug I am trying to work out. I know that the guages work correctly its just the FPR regulator and solenoid that I am worrying about. As I mentioned before, right as the turbo spools, the car go really lean and kind of slows down, the the boost kicks in. I am currently investigating the vacuum set up.

 

[VR-4Galant767]

The problem was an incorrect vacuum diagram for the car. If I had followed the one under the hood I would have been fine. However, when I installed all the vacuum lines, I had no hood on the car.

Thanks for the pointers!