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Topic: Intermittent No Start and Fuel Return Line (Read 2079 times) previous topic - next topic

Intermittent No Start and Fuel Return Line

Reply #15
The return line allows the fuel to circulate.  You could be developing a vapor lock and if the return line is plugged or blocked somehow the vapor lock will not be cleared.  This could also be a function of a weak pump not being able to overcome getting the fuel back to the tank.  The larger the delta P from in the inlet pressure of the pump to the discharge of the pump the more volume the pump can move.  Remember liquid is incompressible.

Drop the tank and start from there.


83 351W TKO'd T-Bird on the bottle

93 331 Mustang Coupe - 368 rwhp

Intermittent No Start and Fuel Return Line

Reply #16
I just went through something similar on my Cougar, but it has 1 pump in the tank. It would run for a few days if I replaced the fuel filter, but it would die and only show 10psi on the gauge. Removing the gas cap didn't help so it wasn't vapor lock in the tank. It ended up being the fuel pump and the fuel pump relay. It would get weaker as it warmed up until the car couldn't run.

1984 Thunderbird - 89 302 HO, Edelbrock Performer 289 intake, Edelbrock 600 cfm 4bbl, Mustang headers, Jegs o/r H pipe, Dynomax mufflers, Mustang AOD and shifter, 8.8" axle

1988 Mustang GT - GT40 heads, Explorer intake, 70mm throttle body, 70mm MAF, Crane 1.7 rrs, E303 cam, Kirban Kwik shifter with Pro 5.0 deluxe handle, aluminum clutch quadrant and firewall adjuster, o/r h pipe, Dynomax mufflers, 3.27 gears.

1986 Cougar 5.0 (sold)
1989 Mark VII LSC 5 speed (sold)
1980 Mercury Zephyr 4 door (sold)


Intermittent No Start and Fuel Return Line

Reply #17
Pull the tank convert it to a single 255 check the return and the regulator and check the pump voltage just for kicks and giggles. Personally i have never seen a vapor lock condition with an in tank system with a return line.  Once again yank the TANK check the intank hose and better yet replace the dual pump with a single unit and call it a DAY!!!
I spend money I don't have, To build  cars I don't need, To impress people I don't know