Well, looked into the SFMU....ripped diaphragm. So i made my own. Hooked everything back up...still 100 psi at idle. So im looking through everything, checking all lines ect... then i realized something. I placed the filter in the return line for some dumb ass reason. Would that create my high FP? lol

ok im really stumped... NO kinks in the lines, replaced the ripped diapragm, put on a high flowing fuel filter. STILL have 100 psi FP at idle. what the hell? yes the little stem is out of the check valve as well. im so frustrated at this omfg PITA. SFMU..running largest disk, dark spring on stock injectors. at 6psi of boost, my WB shows at the highest a 13.0. average i would say 12.5-12.7 The only thing bothering me is that damn fuel pressure at idle wich i can not bring down. One thing i noticed, is that when i play around with the vacuum line connected to the sfmu, once i put it on, the engine rpm goes way down, but the FP remains the same according to the gauge. Its running just fine, no stuttering...just like stock. This is my second FP gauge yet it still reads over 100psi. help :( damn i been searching for two nights now, cant find anything that i havent done already like check lines, check valve, diaphragm ect...

You made your own diaphragm ?? I hope it isn't rubber. :whoa

Is the cap screw on the top of the sfmu wound out? This is the main (static) press. adjustment, not the bleed valve.

Is your static press. 100 or greater I take it? (and you can't get it down)

If you already the above checked, you obviously have a restriction/clog in the return line/sfmu somewhere (after your fuel press gauge). Maybe a piece of this ripped diaphragm?

Take the spring and diaphram out completely and see if the idle stays high. If it does, the problem is either the SFMU restrictor needle (thing the disc pushes down to increase pressure) or you definitely have a restriction somewhere. If the problem lies in the spring and disc area, your fuel pressure would be in the 10-20psi range with the disc and spring removed. You could also pull off the return line at the tank and see if any fuel is returning at ALL. If not, something is completely blocking the return path. A high pressure Walbro fuel pump would reach 120-140psi if it was fully restricted though, assuming thats the fuel pump you are using (you should be...GSS-342).

thanks for the responses. ill do all that once i get home.

ok so came home and did all of what was suggested above. took the spring and disk out, ran the car. still over 100 psi at idle. so checked return line, nothing pinching it. sucked on it, nothing restricting. could it be the sfmu that has gone bad?


edit: bought a new SFMU FTW. if its not that ill just send it back ha

If there is no spring tension on the FMU and you were to blow compressed air through the inlet, it should come out of the outlet with no resistance really. Its either hung up on something or completely jammed. Just try blowing through it, if you can blow thru it with your mouth, its NOT the SFMU.

Originally posted by jack_of_trades
If there is no spring tension on the FMU and you were to blow compressed air through the inlet, it should come out of the outlet with no resistance really. Its either hung up on something or completely jammed. Just try blowing through it, if you can blow thru it with your mouth, its NOT the SFMU.

Just took it off right now. blew through the inlet, there is deffinate resistance. So the sfmu is bad...I have a new one coming in next week, should be here by tuesday. Guess I'll either sell this SFMU as is, or send it to vortech to get it fixed if that wont be too much, then keep it as a spare. I'll post once i get the new one on. Thanks for the info Jamie.

edit: points for you bro. appreciate it

Is it an electronic fuel pressure gauge? If so make sure nothing came loose and is got ground. Mine came loose this weekend and the gauge pegged out at 100psi but my a/f ratio was around 13 to 15 at cruise. Needless to say it was not really 100psi. Just make sure, if its a mechanical gauge then I don't know.

its mechanical. i have an electric one ready to put on so i can monitor from inside. its the SFMU.... outlet is restricted.

Slapped a brand new SFMU on.... got her running fine now. Idle is at 50psi. Now off to the exhaust shop to mate up the down pipe to my Ebay N1 3" Cat Back :) The exhaust looks to be good quality, I'll let yall know how she sounds.

took it out for a spin. runs strong. EGT never goes above 1250 WOT hitting full boost (6psi). AFR is around 12.5. Did notice black smoke coming out at full boost. However i am running an open down pipe at the moment and think i may be running slightly rich with what my EGT is telling me. Next up is giving the local exhaust shop a visit to finish off my 3" turbo-back :) feels great to be boosted!