70 psi fuel pressure baffled
 

Gentlemen, read my analysis carefully please.

When I got my project running 5 weeks ago the fuel pressure was 50-53 as it should be. Car sat for 5 weeks with fresh fuel and fuel pressures were as following
42 psi one pump
80 psi two pumps. 8.2 amps

I replaced the fuel filter which brought it up to
45 psi one pump
85 psi two pumps
Upon applying vacuum to the OEM Fuel Pressure Regulator there was no change so I purchased a FPR from Jerry. Nice piece BTW.

Pressures are now
51 psi one pump. Perfect.
70 psi two pumps.
80 psi spike for 2 seconds when ignition turned on.

FSM says restriction in fuel return. I disconnect the fuel return line at its union parallel to fuel filter. Slip on a rubber hose into a gas can. Retest
51 psi two pumps. Perfect.
I have a restriction between union and tank.
I carefully inspect the SS fuel line from union to tank looking for damage from a careless jack or rear end collision. All is fine.

I remove rubber fuel line line at tank and blow air from each direction. Seems fine. Reconnect union.
70 psi two pumps.

I splice a piece of rubber fuel line to rubber return line at tank and put it in a gas can.
70 psi two pumps
It flows into the gas can but does not shoot with force as I expected.

So problem is between union and end of rubber fuel line at tank.
Has the 18 inch piece of 32 year old rubber fuel return line internally collapsed from the fresh fuel?
Shall I drop the tank and cut off that hose at its crimp and splice on a new rubber fuel line?
Baffled.

Re: 70 psi fuel pressure baffled
 

SOLVED! I found this in the tank return hose. I hack sawed the hard line at the crimp union. This plastic plug was jammed down the hose. Pressure is normal now. Spliced in 11 inches of 3/8 hose.

Re: 70 psi fuel pressure baffled
 

Re: 70 psi fuel pressure baffled
 

Wow! Great troubleshooting! Where the hell is that thing from?


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Re: 70 psi fuel pressure baffled
 

I have no idea what the cone shaped thing is. I had to push it out with a rod. It did not not fall out. The pressure must have swollen the hose to allow gas to pass by the plug. Crazy huh.

Re: 70 psi fuel pressure baffled
 

Glad you got it resolved and that will remain a mystery. That plug needs a case or frame for your car memorabilia display. That?s a head scratcher for sure! :cheers:

Re: 70 psi fuel pressure baffled
 

Looks like a tip from a caulk tube. Wonder what the PO thought he was doing by plugging the return line. WOW.

Re: 70 psi fuel pressure baffled
 

Maybe PO plugged the line while servicing the pumps. The originals were no longer installed. Forgot to take it out when slipping the hose on the pump assembly.

Re: 70 psi fuel pressure baffled
 

That's weird! I'm surprised that you discovered it!

Re: 70 psi fuel pressure baffled
 

I pushed a wire up the hose and it stopped at the hose crimp. So I cut that sucker off!