4.0 fuel issue

[ratney]

Hey guys. Is there a way to check thefuel pressure regulator on a 93 4.0. Truck cranks for about two seconds then dies. I unscrewed the return line off the regulator and there is no fuel coming out of it. I took it off and had gas spew out of the o ring

 

[ashleyroachclip]

To check the regulator , you remove the vacuum lin and loom for gas in the line.
To check for fuel pressure, press the valve stem on the schrader valve.

 

[RonD]

With engine off FPR(fuel pressure regulator) is closed, this is how the fuel system holds pressure in the rail for the next time you start it.
So if engine was off no fuel should come out if you remove the FPR's return line.
If you were to suck(apply a vacuum) on the FPR's vacuum line that would open the FPR's valve, then fuel would come out the return line connection.

There should be 30-35psi of pressure at the fuel rail with engine on or off.
Fuel pump comes on for 2 seconds each time the key is turned from Off to Run.
If you think pressure is low, cycle key on and off a few times before trying to start.


I assume you mean truck runs for a few seconds and then dies??
If it only cranks for a few seconds but doesn't start then could be battery or starter motor or starter solenoid

 

[ratney]

Right it runs for a few seconds then dies. The return line is dry like no fuel has been going through it

 

[RonD]

Well there would be no fuel in the return line, it would drain back to the tank and warm engine evaporates whats left pretty quick after engine is shut off.

You can always suck on the vacuum line or push in the pin on the schrader valve to see if there is pressure, be careful of spraying fuel!
But better to get a pressure gauge and check pressure with engine cranking and then running even if its only for a few seconds.

Pressure should be 30psi minimum, it can go as high as 40psi.


Fuel filter is only $10 and not to hard to change, if you think fuel is the issue I would change that just because.