Fuel Pressure Regulator Problem

CDeutsch · 10-18-2004

I think I found why I can't tune my car for sh*t (including LTFT). My fuel pressure regulator is doing the exact opposite of what it should be doing. Vacuum causes the fuel pressure to increase and it doesn't respond much at all to boost. Here's two 15 second quicktime videos of what's happening. Fuel Pressure gauge is on top, boost gauge is on bottom. The boost gauge reads zero at 9 0'clock and 1 bar at 12 o'clock. Anything from 6 to 9 is vacuum. The FPR was set at 3Bar with the car off and the fuel pump running. It's about 3.2 bar when boost is at zero on the highway.
http://christopher.implex.net/StupidCar/FuelPress1.mov
http://christopher.implex.net/StupidCar/FuelPress2.mov

The boost gauge is tapped into the FPR line. I'm using the Buschur SX regulator. The fuel pressure sensor is on the fuel filter. What in the hell would cause this? I'd take the FPR apart but I wouldn't know what I'm looking for. Has anyone rebuilt one of these regulators? I've used silicone on both the hose bar for the boost source and the adjustment nut on top to eliminate boost leaks. I may try swap a stock regulator on just to make sure that's the problem, but I don't know what else it could be.

Any ideas? I'm surprised I haven't blown my motor over this problem.

**Shane@DBPerformance** · 10-18-2004

See if the spring is broken in the FPR.

It's like a Christmas tree on your a-pillar there.

CDeutsch · 10-20-2004

Unfortunately that wasn't it, but thanks for the starting point. At least I got over my fear of opening it up. I was expecting something a lot more complicated with really small springs that I'd loose, etc. It's just one huge spring (I can't believe vacuum or boost could even affect that sucker) and a couple other parts. Pretty simple. I kind of wonder why these things are so expensive?

The only scenario I can come up with as to why vacuum would increase the fuel pressure is if the ball covering the hole was misaligned and vacuum was causing it to cover the hole more instead of opening the hole more. Although the probability of that is very small. I'll post pics to show peoole what I mean.

I'm not sure where to go from here. I'd ask SX but the FPR was modified by Buschur and I'd ask him but I bought the thing used. I'll probably try reasemble it and give it one more try, before I swap in a stock one. If the stock one checks out, then maybe I'll order a FPR rebuild kit from SX.

Jakey · 10-21-2004

Could you please post up some pictures if you find anything specific when rebuilding your FPR?

CDeutsch · 10-23-2004

Just an update for the archives, thanks to kjewer1 on the DSMLink forum I found the problem. After an hour or two of swapping sensors, gauges, vacuum hoses, etc. I narrowed it down to this; when the boost gauge sensor is under vacuum or boost there is some kind of bug or electrical problem in the control box that causes it to adjust both the fuel pressure and boost gauge. If I unhook the boost gauge sensor or even just the vacuum hose to the sensor, the fuel pressure gauge works fine.

Jackey, I did take some pics of the inside of the regulator. I'll post them on Monday at work.

CDeutsch · 11-01-2004

FWIW, here's the pics of the FPR cracked open:
http://christopher.implex.net/pics/1020-FPR/

Enes · 11-01-2004

the expensive part is the rubber they used inside the thing..

lol j/k i don't know.. must be the cnc costs... because aluminum blocks are dirt cheap..

-E

CDeutsch · 11-05-2004

Well I talked to Apexi and apparently only two people with the same issue isn't enough. They want me to call back if I find more. So if anybody knows somebody that's using the Apexi EL II Meter System let me know because I'd like to get in touch with them.

I swear there was another post in this thread about someone else "parting theirs out", but it wasn't clear from the post what the problem was. If you're still out there let me know.