Hi all I'm looking for some help. I have a 93 f150 5.0. I don't really have much experience with fuel injection motors. I have rebuilt the engine and got it back in the truck. I put all new fuel injectors in and found some was stuck open. I put in another set thinking I may have got some bad ones. Some of these are stuck open too. When you turn the key on the fuel pump comes on and don't shut off. You can hear the fuel spraying thru the throttle body. It will completely fill the cylinder with gas. I have a new set of Bosch injectors on the way. It builds up 40lbs of pressure on the fuel rail and slowly leaks down when you turn the key off. Any help as to why I keep having the problem is appreciated.

Thanks kenny

 

Injectors work light light bulbs. If you have power and ground, they will turn on. When the key is turned, there should be power to the injectors. The ground comes from the EEC-IV ECU. The fuel pump should be on only when the engine is moving and when you first turn the key [for a few seconds].

Sounds like you got wiring or ECU issues.

 

Ok thank you I will check the wiring and ecm. Another quick question is should you be able to blow air thru these injectors? Some I can and some I can't. I tried blowing air thru them because I thought maybe the stuck ones had some trash in them. The stuck ones I can indeed blow air thru. Thanks
kenny

 

When the injector is unplugged, they should be sealed.

If they are stuck open even when they are unplugged, you might want to check what's going to them. Is the fuel filtered at all? There are tiny filters inside each injector as the last ditch effort to keep the junk at bay, but unless you got some fake/cheap injectors, they usually do not fail because they are stuck open.

 

Classic symptom of a bad computer (PCM). You most likely have more than one problem to solve.

 

Any way to test the ecm on these trucks? All wires look good. I checked them over and can't find any that look bad anyway. has fairly new fuel filter. Could I have maybe got something in the fuel rail while I had the engine apart?

 

Run the Key On Engine Off (KOEO) tests and Stored Code display is the best testing you can do. You may get codes, even a System Pass for each, or you may not get anything. History has shown when the fuel pump energizes with the key in the Run position but never shuts off the MOST common causes are 1. Bad computer or 2. Someone prior to you wired the fuel pump that way.

 

Well I removed the fuel rail and blew air thru it seem like maybe a dirt dobber got into it. Blowing air back thru the stuck injectors some trash came out. So with a third set of new injectors installed its now running like it should. Thanks for all the help. Lesson learned.

Kenny

 

Does the fuel pump shut off after 1-2 seconds when cycling the key from Off to Run?