Ford F150 help

[Kingman]

I know this isn't a Pathfinder, but maybe a few people have some ideas. For the past week or so my buddy's '99 F150 4.6L has been running pretty rough with a check engine light (code is misfire - go figure ) and today I took the day to try and figure out what's wrong since he's not too mechanically inclined yet. Earlier he had someone replace the coil packs and that didn't help at all, it's still misfiring. I went through and pulled each plug wire off to see which one made a difference and the 3rd cylinder on the passenger side did not. I then pulled the fuel injector harness clip for that cylinder off and that made no difference either. The plug and wire both have spark...how do I know? I accidentally shocked myself and it threw me off the 38" tire I was standing on. The plugs and wires are all new. My first thought was a bad injector (160k, wouldn't be too far fetched) so we went ahead and replaced that since it wasn't expensive and it made sense. Well that didn't make any difference after resetting the computer, so I pulled the entire fuel rail off all of the injectors and had him crank it over and fuel squirts out all 4 ports with great pressure. So I hooked all 4 injectors up (but not in the block, with a towel underneath to catch all the fuel) and all but that one injector fired so I thought we got a bad injector from the store so I swapped them out and the problematic one wouldn't fire, but the new injector fired fine on a different port so it's not bad.

 

Something is keeping that one injector from firing and I have absolutely no idea what kind of computer is on these rigs to make it do something like that. It didn't gradually get worse, it suddenly started running rough and smelled like gas out of the tail pipes.

 

I'm hoping it's not a cut wire somewhere because that would be a total b!tch to trace down throughout the entire wiring harness.

 

Any thoughts?

[GoPathyGo]

Your first problem was getting/keeping a Ford.

 

Sell it, junk it, throw it away, whatever is necessary. Then get an R50.

 

Sorry nothing useful to add.

[Kingman]

 

I knew that would come up. He gets all the chicks though, girls love lifted trucks...

[Simon]

Check to make sure that you have voltage at the clip for the injectors. Or, swap two of the connectors for the injectos, and see if the problem moves. Then you know you have a wiring issue.

 

If the problem remains on that injector, it could be that the lines are plugged.

[94extreme]

if you got fuel coming out the tail pipe.. the fuel isn't burning correctly.. check gaps on the plugs and make sure the plug wires don't cross.. also, make sure that fuel filter is free of clogs.. those are the only things that ever made my f150 stumble. (carburated older model, 302 motor)

[nismothunder]

Well since you already replaced/checked every thing I could think of I'll go out on a limb and say maybe the computer in the truck itself is going bad.

[Kingman]

I forgot to mention I did cross the wiring clips for other injectors and that didn't make a difference.

 

It's getting plenty of fuel to the injector rail, but the plug was dry and gapped correctly - it's not getting any fuel in to that cylinder.

 

I didn't even think about checking the clip with a voltage meter