truck fuel pressure drops and dies after 10min idle
<HR style="COLOR: #666666" SIZE=1>On my 88 f150 4x4 4.9efi mazda 5 speed 131,000 miles

New problem: I stuck the fuel pressure gauge on and it is registering about 45 while running, which is low should be 60 psi. It will stay at 45 for about 10 minutes then the pressure drops and the engine dies. The pressure will not come back unless i wait for about another 15 minutes then the pressure is up and the truck fires right back up. I do the pressure test and once it is back to registering 45 psi with the key on engine off the truck starts right up. I am also getting the following codes: 67, 21, 33, 51, 95.

When the truck is idling it is nice and smooth and sounds great.

one other thing to add, if i ground out fp lead on the dlc connector to test the fuel pump the pressure is a steady 55psi from both the front and rear tanks.


Help,
Darren

 

Check the fuel filter. Sounds like might have plugged up. Gives you enough to run for awhile but not enough to keep system full.

 

i will go ahead and replace the fuel filter. hopefully things will improve after doing so.

 

Is there anyone out there that can give me any other ideas?

Thanks,
Darren

 

My 90 5.8L has a fuel pressure regulator located at the aft end of the fuel manifold. I would assume you have a regulator somewhere in your system that provides for bypass of unused fuel back to the tanks. Just guessing, as the regulator warms, it may be allowing the pressure to slip a bit......