fmu or somthing else?

[SCedGSR]

After 18 mths of being boosted I think I have my first bad peice of equipment.

I can't get my wot fp above 80 psi. I still have all the basic stuff that comes with the stock kit. fmu, etc...

I have adjusted my static fuel pressure all across the board from 50 to 85(adjustment screw all the way in), and no matter what when at wot the guage will only read 80psi. At static 85psi the guage actually backed up to 80.

Is the JR fmu dying on my or something else?

[JRCivic]

It could be the FMU Nick, however, I wouldn't rule out the fuel pump just yet either.

[SCedGSR]

The pump was my first guess. It's the GSS-317, what can I do to test the pump?

[CROM]

If I was given my choice of FMU or Fuel pump, I would say FMU...now, my first JR FMU that came with my kit has actually never failed, but the second one I got as an accidental backup unit failed on me 3 times in 6 months(speaking of which, I need to send it back to JR). My fuel pump however has been rock solid for 4 years.

The best way to tell if your FMU is screwed is by inspecting the wheep hole (the little hole underneath your mounted strap). This will leak fuel if the diaphrams are broken. You can also just open up the FMU and check for damanged diaphrams.

[SCedGSR]

when I have my static at 55 - 60 when I hit the gas the guage will read btw. 90-95 then immediately backup to 80psi. This is what first lead me to believe that the pump was bad until I raise my static pressure all the way to 85-90.
At idle the pressure was consistent at that psi. Once I would hit the gas the pressure would back up to 80psi.

[JRCivic]

Check your belt tension Nick. See if you are losing 2-3 psi when the fuel pressure drops down from 95-80...

Don't forget to check BOTH belts.

[cpa]

I believe you should be able to test your fuel pump by briefly pinching off the fuel return line and seeing what the gauge reads. Are you sure it's not reading higher than 80 psi, then backing off because the 317 doesn't like high pressure? Maybe you have a loose belt and are losing boost at high RPMs?

Do you see your fuel pressure rise under boost when you set the static at 50, compared to setting it at 80? Could it be that the FMU isn't seeing boost for some reason - a disconnected or leaking vacuum line? Maybe the gauge is just bad?

[SCedGSR]

Boost guage reading 6-7 psi as usual. Belts seem fine.

When the pressure drops i am getting yellow leds on the a/f guage. I've heard detonation on a couple occasions.