Fuel pressure too high

[turbolimited]

What are the good reasons I haven't thought of or found in search that would result in seeing high pressures (not lower than 48 psi, vac line off)? New Walbro 340 pump, stock sending unit and lines, multiple AFPRs all with same result. The car was down for like 8 years before this problem arose. I installed a new fuel tank, new pump, but everything else on the car is how it was when it ran, normal pressure.

I have "flushed" the all the fuel lines, backward and forward with compressed air. The return seems free of any blockage or restriction. It acts like the pump is just too big for the factory lines, but it is just a little ole 340.

Combo, if it matters: stock block, ported irons, small flat tappet cam, ported lower intake, champion upper, 70 mm. TB, RJC front mount, Razor's Alky kit, TE 45A, 60 lb. injectors, new Accufab, old Accufab, old Bosch AFPRs, stock fuel rail, stock lines, new filter and sock, Walbro 340, stock sending unit.

It has to be a restriction in the return line, right? I have pretty much ruled out a restriction, which means the pump is too powerful, but that doesn't make sense to me either given its size. Anything else to try before replacing the return line or dropping the tank to check and see if this is really a 340 in there?

 

[dynoman]

Maybe you kinked the return line when replacing the tank . Try dropping it down a little to check . You can try running a line straight from the return at the rail to a bucket and turn the pump on with the jumper near the alternator . This would verify if the factory return is the problem .
Air through the lines flows much easier than gas .

 

[turbolimited]

Thanks, Sam! In the process of blasting the lines, I did drop the tank and ran compressed air from the lines at the sending unit forward. I didn't see any kinks. I'll try the straight line off the return into a bucket and see what is happening. I'm not totally opposed to running a new dedicated return line from the rail all the way to the tank, but would like to save the effort and expense if possible.
thanks again!

 

[THensley]

fuel pump to large for the return line and stock hanger

 

[THensley]

255 is all needed for 60's