255 LPH pump...return line pressure too high...ideas??

84LX89GT · 05-11-2003, 04:39 AM

I put a 255 lph fuel pump in last week (preperation for my nitrous system i'm going to install) and when i checked fuel pressure i adjusted it down to 35 from 40 key on engine off....started it and it was up to 85 psi. I pulled off the return line and ran a hose from the fuel rail return (after the regulator) into a gas can. Pressure dropped to 35 psi with the engine running.
After reconnecting the return line, the pressure went back up to 85 psi.
I dropped the fuel tank and pulled off the return line at the pickup assembly to see if it was the pickup, and pressure remained at 85 psi with the fuel pickup out of the loop. I checked along the return line to see if it was pinched anywhere, but it wasn't. The line looks intact and i can't think of a cause for this except for the line being too small for pump.
Has anyone else run into this?
Am i going to have to route a larger return line to the tank?
Any suggestions on what i should do?
I'd like to do this on a budget beause i can't afford new fuel rails, and whole new fuel system with special pickup....i can save up, but it would be awhile for a fancy system.

qtrstang347 · 05-12-2003, 07:31 PM

you probly pinched the return line between your tank and frame when you reinstalled the tank, and when you drop the tank back down you cant see where though. just make sure the lines go through the indention on the tank between the frame.

05-11-2003, 04:39 AM	#1
84LX89GT Mustangs Join Date: Jul 2000 Posts: 1,938	255 LPH pump...return line pressure too high...ideas?? I put a 255 lph fuel pump in last week (preperation for my nitrous system i'm going to install) and when i checked fuel pressure i adjusted it down to 35 from 40 key on engine off....started it and it was up to 85 psi. I pulled off the return line and ran a hose from the fuel rail return (after the regulator) into a gas can. Pressure dropped to 35 psi with the engine running. After reconnecting the return line, the pressure went back up to 85 psi. I dropped the fuel tank and pulled off the return line at the pickup assembly to see if it was the pickup, and pressure remained at 85 psi with the fuel pickup out of the loop. I checked along the return line to see if it was pinched anywhere, but it wasn't. The line looks intact and i can't think of a cause for this except for the line being too small for pump. Has anyone else run into this? Am i going to have to route a larger return line to the tank? Any suggestions on what i should do? I'd like to do this on a budget beause i can't afford new fuel rails, and whole new fuel system with special pickup....i can save up, but it would be awhile for a fancy system. __________________ 2005 Suzuki Hayabusa GSX1300-R 1980 Ford Thunderbird - 255 V8 ported heads, 5.0L ported stock headers, O.R. H-pipe and Flowmaster 2-chambers, dual roller timing chain hi-po Mack Truck hood emblem 1985 Mustang GT 5.0L T5, F-303, GT40p, headers, off-road h, flowmasters, MSD stuff, etc. Sold 02/06/04 1989 Mustang GT ET: 13.304@102.29 mph (5-24-03) Sold - 1998 Mustang Cobra coupe, 1/4 mile - street tires: 13.843@103.41 (bone stock)

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05-12-2003, 07:31 PM	#2
qtrstang347 Registered Member Join Date: Dec 2001 Location: Co Posts: 4	you probly pinched the return line between your tank and frame when you reinstalled the tank, and when you drop the tank back down you cant see where though. just make sure the lines go through the indention on the tank between the frame.