I have a 1995 ranger 3.0L pulled plugs found #1 plug wet and black... cycled key with fuel gauge hooked up to fuel rail pressure would drop if i left the key on if i turned it off it would hold pressure. I ended up replacing injector anyways, still having same problem.
Help me please!!

 

well you may have more than 1 injector leaking, 1 was just more prevalent. I dont know if you have a carb/FI shop but these can be reconditioned/cleaned fairly cheap. But you can also get remans pairly cheap also and replace all. Also you might have a weak by pass valve if there isa one in the system allowing it to bleed down, as I actually think it is supposed to but I am not positive. You didnt say how long it took to bleed down so maybe someone else can chime in on this because when you turn the key on it is supposed to pressurize the system, in this case it could possibly be maybe a weak fuel pump? How does it maintain pressure once its running and the throttle advanced?

 

Welcome to FTE.

Let think about this some more.

Do you have a CEL lit, if so, scan the computer for trouble codes & post All code Numbers, as they can offer up good trouble shooting clues.

If no codes, did you pull & inspect all of the other spark plugs???? If so & they all looked ok, maybe suspect a wiring or computer ground switching driver problem.

With #1 plug looking as you described, it holding fuel pressure ok with the key off, but pressure leaking down with the key on & still doing it after the injector was replaced, it sounds to me like an electrical problem, as the injectors have B+ to them when the key is in the run position.
Maybe a wiring problem on the injectors ground return to the computer, or a computer driver problem, if the driver isn't switching the injector ground connection completely off. SO, try disconnecting the #1 injector when leaving the key on & see what happens with fuel pressure.
If pressure holds, do a voltage check to ground, across the contacts at the injectors disconnected plug with the key on/engine off & let us know what you find.

 

pawpaw

I think we're on the same page... Tried all of this yesterday after i made the post...

No Engine warning lights are on...

I did pull all the plugs the others were getting pretty white like they were running lean... Cycled key with all plugs out and #1 cyl. filled with fuel...

Fuel rail does hold pressure with the #1 injector unpluged, and tested for ground at the plug with the key on/engine off return ground wire is grounded... Also checked for short to ground at #1 injector plug with harness unpluged from ECM (not grounded)... So that should rule out the harness right??

To me sounds like I have a bad ECM?

I can order one from Autozone... Does it need to be flashed by a dealer or am I ok just to swap it out...

Thanks for your help!

 

[quote=chris3075;10956768]pawpaw

I think we're on the same page... Tried all of this yesterday after i made the post...

No Engine warning lights are on...

I did pull all the plugs the others were getting pretty white like they were running lean... Cycled key with all plugs out and #1 cyl. filled with fuel...

Fuel rail does hold pressure with the #1 injector unpluged, and tested for ground at the plug with the key on/engine off return ground wire is grounded... Also checked for short to ground at #1 injector plug with harness unpluged from ECM (not grounded)... So that should rule out the harness right??

OK, good trouble shooting & feedback. From what you've posted, I agree it sounds like a computer ground switching driver problem for #1 injector.
If you know an electronic tech, he may be able to replace the driver or it's control circuit, or what ever is bad & it'll likely cost way less than a reman computer.

Be sure to replace the computer with a matching part number, then go through the cold & warm idle relearn proceedure with the replacement computer & be good to go without driveability problems, as the computer can usually learn the remainder of what it needs too, as we drive. In any case the short & long version Ford computer relearn driving routines have been posted on the forum, so a search will turn them up.

Let us know how it goes.

 

Thanks for all the help and confirming my findings... just installed a refurb. ECM this weekend seems to have fixed the problem... if the problem was in the ECM why did it not set a check engine light.

 

OK, good find, fix, feedback & to hear all seems ok & your on the road again.

I don't rightly know why it didn't set a CEL. My 94 Taurus recently had a random stall, that was caused by spark going missing. It was traced by process of elimination to the computer, it too didn't set a CEL or store any trouble codes.

I suppose the circuit or faulty component wasn't being monitored by the CEL circuit for self diagnosis.