Well I tuned my 440's to aroudn 18psi for idle fuel pressure and turned the boost up to 15 psi . But at wot my fuel pressure only hits around 40psi and leans out fast so I cant step on it for that long in any gear. I use the largest ring, 2.72 disc and short gunmetal colored spring for the sfmu. I thought my fuel pressure should be around 80psi at wot. Any ideas what to do

http://www.vortechsuperchargers.com/pdf/manuals/superfmuim.pdf

Read #5 regarding the boost set screw. This is designed to limit the amount of fuel pressure you top off at. Make sure your SFMU is set up properly and adjust it properly. Most problems have been related to user error.

I also noticed you are running an inline pump to raise pressure. Make sure your pumps are both good. A quick way to test them is pinch off the return line to see if your fuel pressure raises on your gauge. IT should top off around ~120 PSI.

For future get a walbro.

Terry

I had a walbro go bad and would only make ~40psi.

I dont have a walbro I use the accel inline pump with the hahn kit. I dont have a screw in the boost hole on the sfmu. There is a screw in the boost and vacume holes only.Also I lost the restricto piece that is suppost to go in the vac line 2-3 inches away from the sfmu could that be causing the fuel pressure not to go up

It's not a screw. There is an allenhead adjustment inside the whole that needs to be turned all the way in. If that is not in there you need to plug it with a screw.

Originally posted by sike
It's not a screw. There is an allenhead adjustment inside the whole that needs to be turned all the way in. If that is not in there you need to plug it with a screw.

There is nothing in the boost hole at all. Should I take one or the screws out of the vac or bleed hole and use that instead or just get any screw that will fit and put it in there.

Find a new bolt that will fit.

The screw is all the way turned in the sfmu and as soon as the boost goes up my car leans out and I have to let off the gas. My idle fuel pressure is 18psi will raising it help? I dont understand why as soon as my boost goes up to 15psi the egts shoot right up to 1600 and I have to let off.

What are your fuel pressures under boost? You might have a bad pump.

My fuel pressure under boost is 40-45psi. Ever since I put in my 440's the accel inline pump has been allot louder. I dont know if this is because of the injectors or if my stock intank pump went out. The vac screw on the sfmu does nothing when I turn it and dont know what else to do.

Check the diaphram for rips. Then try 10 or 12 psi and see what happens. what are you using to tell if your lean? Try a datalogger over the blinky gauge if you dont have a wideband

The diaphram is fine and my egts go sky high as soon as I get close to 15psi. Also with 440's I thought you should be around 18psi fuel at idle.

be sure there is a cap off screw in the bleed port. If this is left opened up, then a lot of boost pressure inside the sfmu chamber will leak out, and the sfmu wont raise fuel pressure.