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I had the same problem with my Corvette filter/regulator install. The fuel pump would override the FPR. It was a Racetronix 340 LPH pump though. Tried several Corvette FPR´s
Ended up installing an aftermarket FPR on the fuel rail end.
I went with the "ebay special" 6an FPR. Welded a 6AN SS fitting at the end of the fuel rail where the service port used to be and made a direct connection. Return line coming off the bottom via a 180 deg tube. So far so good.
Did more troubleshooting today. I rigged up a totally new fuel system in a bucket to rule out the feed line from the tank and the feed line from the FPR to the fuel rail. Fuel pressure is still at 70 psi.
To recap: I've replaced the FPR, ran a new return line to a bucket, ran a new feed line using my spare fuel pump in a bucket, ran a new feed line from the FPR to the fuel rail and I'm still getting 70 psi.
I think the only other component left in the fuel system is the fuel rail. It was a brand new LS3 intake assembly when I bought it so not sure how anything could've gotten in there to clog it.
I installed a new stock fuel rail since it was the last component I hadn't ruled out. No change. Just to be super thorough I checked pressure with an analog gauge and got the same 70 psi.
At this point I have ruled out every single component of the fuel system: pump, feed and return from the tank, filter/ regulator, feed line to the rail, the rail itself, and the gauge. I am officially stumped. Might have to get an adjustable regulator.
Just found a FAQ page on Aeromotive's website that said a Corvette filter/ regulator will cause false high pressure when used with any fuel pump that flows more than 250 LPH. Since I'm using a Walbro 255, I'm sure that's my problem. Wish I would've found this weeks ago! Looks like I'm gonna have to get an adjustable FPR and I'll put a stock fuel filter back in the stock location. I'm most likely going to get an Aeromotive adjustable FPR with -6an ports since finding -an to quick release fittings is super easy at that size.
My 98 Wrangler LS6 swapped has a 255 Walbro. Been using it for 14? years. Its been fine. My current project 80 Camaro with a LS3 swap with a 255/C5 FFR is right at 56 psi at the fuel rail. On both I'm running a AC Delco FFR.
Just a question. On the Aeromotive regulator will you have to run a return line all the way back to the tank or will you mount it in the back for a short return line?
I'm running an Aeromotive 3.5 brushless pump with 10AN-8AN feed lines with an adjustable FPR that's in the engine bay and decided to run a return line all the way back to the tank which is probably better for regulating the pressure at the engine and keeping that high dollar pump happy happy happy.
Just a question. On the Aeromotive regulator will you have to run a return line all the way back to the tank or will you mount it in the back for a short return line?
I'm going to put it where I have the current FFR mounted. That will make use of the stock lines including the return line going back to the tank. You can see a picture at the start of this thread.
Got the adjustable fpr installed. The instructions said to use o-rings but they didn't work with my Summit AN to quick disconnect fittings so I used ARP thread sealer. Everything works great, no leaks, fuel pressure now at 58 psi
What car is that? I've never seen an F-body with the fuel lines entering the left front wheel well like that. IMO it looks like a dangerous place for them to be routed. Perhaps the LT cars had their fuel lines routed in that manner.
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