Hello everyone. I have a 93 with 5.0 EFI thats making me crazy. Sometimes it starts and runs fine sometimes no start. The one hint i have noticed is when it wont start the fuel pump continues to run. When nit does start the pump runs a couple seconds then stops. Is there a sensor that tells the pump the system is primed and allows start?? Any help will be highly appreciated.

 

On your car, the fuel pump is either on or off. With the ignition in the 'on' position, the pump should be on, continuously running. If it only works intermittently when in the 'on' position, chances are your pump is dead. If you can test to make sure your relay is switching as it's suppose to, then you can rule that out (get out your multimeter and make sure when switched electricity actually passes through, at steady numbers). But, the symptoms sound like a dead pump, as usually they will run fine until they start causing starting issues.

 

Thanks for rely, what gets me is if pump comes on 2 or 3 seconds then stops it will run fine. if pump stays on it will not start. showing about 40 lbs pressure eigher way. dont want to just start throughing parts at it.
thanks

 

Observe the pressure while cranking. I can almost guarantee that the pressure will drop because the pump is too worn to supply the required fuel demand. If power is going to the pump, then the pump is dead. Even if it isn't dead, you're talking about a '93 car. If the pump is original, it's way past borrowed time. Now, the other suspects can be the electrical (is everything connected, did a crank/cam sensor fail?). However, the electrical bits that would prevent starting are not going to fail in this manner, whereas these symptoms are typical for a dying pump.