I have a 91 Dodge P/U 318 engine that will not hold fuel pressure. I have installed 2 new fuel pumps( Napa brand ) with the same results. It will pressure up to 15lbs at idle, but once you give it any kind of throttle the fuel pressure will fall and it will stall out. I have to cycle the key a few times to get it to pressure back up to crank. The fuel lines are not plugged, pressure regulator has been changed. There is good voltage to the new pump. I have also crimped the return line to see if it was bypassing. Any ideals and thanks in advance.

Sorry for the double post, I posted in the 2nd Gen by mistake.

 

Any pinhole leaks in the fuel lines?

Is the vacuum source for the pressure regulator free and clear?

You might try getting a tune up kit for the throttle body and soaking it like you would when you rebuild a carb.

Are there any error codes stored in the computer?

Are the map sensor vacuum hose and ports clean?

Have you carefully looked into the TB and observed the fuel spray pattern as the injectors work and during the stall?

Check the caps on top the injectors, they have electrical contacts that can get loose or corrode.

You might have a bad injector or o-ring seals or partially clogged injector. Get a can of SeaFoam from NAPA and run it thru the gas tank.

Any vacuum leaks?

When testing for pressure holding, make sure the gauge is securely attached to the fuel line, start the truck and when the pressure gets up to 15# which should be immediately shut the engine off, the pressure should remain constant for at least 1 minute. don't rule out a problem in another area like the TPS or ignition.

This should keep you busy for about 10 minutes!

 

after scratching my head for alittle while I found my problem. It ended up being the flex fuel lines by the tank where coming apart and blocking the fuel flow.

 

Glad to know your problem was remedied