Help! Sky high fuel pressure
 

I have a couple of 502 mpi's with side mounted whipple chargers. Starboard motor runs great. Port motor's fuel pressure out the front of the fuel rail is 80-100. GET THIS- fuel pressure at my aeromotive regulator is dialed in at 45. I have swapped areomotive fuel pumps, areomotive regulators,fuel water separators,fuel coolers, drained and filled the gas tank with fresh fuel. I think I my have some sort of restriction in my fuel rail. I had all my injectors tested and cleaned. I was thinking of swapping fuel rails first and then possibly injectors. Well guys & Gals - I'm all ears. Any advice?:(

Blocked return line?

have you tried swapping gauges???

Sky High 502 mpi fuel pressure
 

I just swapped out the return line from the front of the fuel rail that goes back to my aeromotive regulator. Fuel pressure didn't change -was still 80-100:( I think I may have a blockage in the fuel rail or an injector problem. I think I'll try swapping out fuel rails next. Am I going about this right? Trying to eliminate possible sources of the problem. As always I'm all ears. Looking for more ideas:eureka:

had a blocked return line do the same thing. good luck

blocked return screen
 

Tonight I found a small approx. 1/4 inch cone like screen on the front of my fuel rail return. It had some black imron paint flakes on and more around it. Paint flakes where also in injector screens. Question: Do I really need the fuel filtering screen on the front of the rail? I think - TOSS IT. Any foreign matter goes to aeromotive regulator,fuel cooler then returns to fuel/water separater where it should get trapped. What do you guys think?

Re: Help! Sky high fuel pressure
 

Poolshrk -

Hope you are still out there. Found the same issue on my 1999 Whipple 502 today. Fuel pressure is 43 at idle(good)but spikes to 80-100 psi near WOT. What did you find out? I am used to 43 at idle and 50 at WOT.

Re: Help! Sky high fuel pressure
 

I would defently leave the screens in place, especially if it was plugged. The fuel/water seperator is just that, a fuel water serperator, its not realy that good of a filter. I have seen many fuel rails, and other hard lines that were corroded on the inside and although the pieces that come off of them are tiny they are enough to make an injector do funny things, bottom line is I would never even consider removing those screens.

Re: Help! Sky high fuel pressure
 

I didn't see in the list of equipment in your first post where a fuel filter was installed, only a fuel-water separator. I say clean everything out, install a filter like a Racor inline with your water separator (or if you get one with a fuel/water separator, just replace it), and you won't have any more trouble. You shouldn't have something the size of a paint flake making it to your pump and fuel rails.

I'm running a Racor with a 2 micron filter upstream of my EFI system, and it hasn't let me down yet. I see 45 psi on the rail all the time. I was unable to mount it deep enough in the bilge, so to prime it, I have to press up the tank with an air pump via the vent, and bleed off the filter bowl, but that's only a once a season event unless I run it out of fuel or forget to shut the tank suction stop valve before opening the filter cap.

Re: Help! Sky high fuel pressure
 

If it is a Cool-Fuel system, check the filter under the regulator mounted on the fuel cooler. It is #14 on the diagram below.

Dave