i start the car up after finishing install of sfmu . 55psi at idle . then i tried to ajust idle pressure . it wont change so i quit for the night . next day start the car up now its at 60 psi idle . try to adjust it and nothing . check for kinks in the return line and couldnt find any . so finally today i start the car and its at 70 psi idle so i took the sfmu apart everything looks good no rips in the diaphram . does anyone have a clue whats going ? i cant understand why its doing this . im really frusterated at this point . oh yea by the way im runnin stock injectors ,walbro 255 ,largest disk with dark spring . fuel pressure is rising with boost tho .

Maybe a kink in the return line? I'd check that avenue since you've pretty much run through the possibilities.

Originally posted by boosted60trimrst
...check for kinks in the return line and couldnt find any ...

He already did.



Did you get the s-fmu new or used? if used you could possibly be missing some parts. it should go together like this: disc/ring combo, diaphrahm, small plate, spring, another small plate, cover.

Have u checked to make sure all of the screws are tight? my boost screw was a little loose and i didn't know it, that made my fp impossible to change. make sure they're all nice and tight. the boost you need an allen wrench for.

Opps didn't see that part about him checking already. How about the guage itself? Can you check if that is the bad part in the link?

Originally posted by willmayo

Originally posted by boosted60trimrst ...check for kinks in the return line and couldnt find any ...

He already did. Did you get the s-fmu new or used? if used you could possibly be missing some parts. it should go together like this: disc/ring combo, diaphrahm, small plate, spring, another small plate, cover. Have u checked to make sure all of the screws are tight? my boost screw was a little loose and i didn't know it, that made my fp impossible to change. make sure they're all nice and tight. the boost you need an allen wrench for.

thank you ...the boost screw is one thing i didnt check . ill check it first thing in the morn . all the peices are inside . i did get it used from 420aturb . how would i check to see if the gauge is working right ?its brand new b&m .

Did you remove the schrader valve from the fuel rail test port?

do you have good vacuum going to it? have you tried the silver spring at all yet either?

It's probably not the gauge. Internal parts in the sfmu could be damaged. If you have no kinks in your return line and you are absoulutely sure you have the hoses and everything on properly to the right places, it could very well be the sfmu. You could do damage to the sfmu by screwing the adjusting bolt in too far or dropping it. The first SFMU I bought was broken and I was having the problem you described. It took me a week before I decided to send it back to Vortech and they determined it was broken and shipped me a new one (after 3 weeks and alot hassle, DIE VORTECH). Anyhow start the car without the top on the sfmu and see what happens, it adjust pressure by the piston in the center, the more pressure applied the less fuel allowed to return to the tank therefore raising fuel pressure at the rail.

Originally posted by sike
It's probably not the gauge. Internal parts in the sfmu could be damaged. If you have no kinks in your return line and you are absoulutely sure you have the hoses and everything on properly to the right places, it could very well be the sfmu. You could do damage to the sfmu by screwing the adjusting bolt in too far or dropping it. The first SFMU I bought was broken and I was having the problem you described. It took me a week before I decided to send it back to Vortech and they determined it was broken and shipped me a new one (after 3 weeks and alot hassle, DIE VORTECH). Anyhow start the car without the top on the sfmu and see what happens, it adjust pressure by the piston in the center, the more pressure applied the less fuel allowed to return to the tank therefore raising fuel pressure at the rail.

where were you when i had the trouble with my sfmu!!!!!!!

i checked the boost screw today .its tight . i have a feeling it might be internal . i didnt drop it or screw the adjusting bolt to far tho . its really driving me crazy . its been like 2 and a half weeks sinse i drove my car . im about to call vortech tommorow . thanks for all the help . thats why i love this site . by the way should the piston in it move down when pressed ?

If I remember it is pretty tight, and will not press very far or very easily, it is very sensetive. Do not put alot of pressure on it.

i am so happy right now . i fixed the sfmu problem and it was such a little stupid thing . i feel retarted . the problem was at the end of the return line where i clamped the hose down . right where it go's to the tank . i put two hose clamps to make sure it didnt leak . well 1 clamp sort have misssed the barb and kinked it . i took the return line off the first time and blew compressed air into it . the air went through fine . then put the two clamps back on . it still didnt work . so today i figured i check the return line again but this time i didnt put the hose clamps on actually by mistake . and it worked .. yyyyaaaayyyy .i set the idle fp to 51psi and it ran beautifully .3 weeks cuz of a f'n hose clamp . lol