i just hooked up my sfmu . big disk , dark spring , stock injectors running 5psi . well the b&m fuel pressure gauge i bought needle shakes like crazy at idle . if i rev the engine to about 3000rpm it will go solid and wont shake anymore . why is it doing that is it normal ? i tried to tune the sfmu and i only can change the pressure about 1 psi . thats pobably because i dont have the restrictor right ?i read that people just use welding tips . but what size ?
also does anyone have a pic of the screws on the side cuz i might be missing the boost screw . sorry for another sfmu post but i really need the help .

btw there are no leaks and no kinks in the hoses .

Yes the needle on the B&M fp gauge shaking at idle is perfectly normal. I have the same setup you do and mine does the same thing. The only part of the SFMU that needs a screw is for the bleeder port. I would just order a bleeder valve for it and call it a day. I think you can get them for like $35 or something like that. I think Vortech wants $60 or $80 from their main site.

thanx a lot . happy to know my gauge isnt broken . but it moves so fast it hurts my eyes lol . also i know i should be running about 48psi at idle. right now its about 54 psi . thats the lowest i can get it without the restrictor . but my static is about 55 .(wont change at all) . i know thats wrong . what should the static fp be?
right now at idle my o2 voltage is cycling from about .18 to .94 . what should it be ?

Originally posted by boosted60trimrst
thanx a lot . happy to know my gauge isnt broken . but it moves so fast it hurts my eyes lol . also i know i should be running about 48psi at idle. right now its about 54 psi . thats the lowest i can get it without the restrictor . but my static is about 55 .(wont change at all) . i know thats wrong . what should the static fp be? right now at idle my o2 voltage is cycling from about .18 to .94 . what should it be ?

There is no exact o2 voltage at idle. As long as it cycles back and forth, then it is fine.

your probably not missing a screw, its probably the one that is really small and has i believe a hex head. Your idle fp is fine hahn recommends between 47 and 55 psi, if i was you i would err on the high side until you can get it tuned, i've got mine set at 55. I would also suspect your static fp to increase more than 1psi over idle fp. I'm assuming you have an upgraded fuel pump, if not maybe that's your problem. You can check to see if fp is rising as it should with just a small air compressor.

Originally posted by cs82685
your probably not missing a screw, its probably the one that is really small and has i believe a hex head. Your idle fp is fine hahn recommends between 47 and 55 psi, if i was you i would err on the high side until you can get it tuned, i've got mine set at 55. I would also suspect your static fp to increase more than 1psi over idle fp. I'm assuming you have an upgraded fuel pump, if not maybe that's your problem. You can check to see if fp is rising as it should with just a small air compressor.

i have a walbro 255lph . ill check to see if it rises with the compressor tomm. the other question i wanted to know what size welding tip can i use for the restrictor ?

ok i start is up today ..take off the vac line . i tried to set the static and it barely moved . it is at 60psi . then i put back the vac line with a .032 welding tip for the restrictor . now my idle psi is at 60 also and i cant change it . i drove the car anyway and it runs pretty smooth so fp is rising but how come i cant lower it at static and idle ?

anyone ?