1993 XLT 4.0 Running on 3 cylinders, need help please.
#1
1993 XLT 4.0 Running on 3 cylinders, need help please.
Truck ran rough suddenly 2 years ago. Been parked until now. No fuel pressure when key is cycled 3 times as Schrader valve is pressed. Replaced fuel pump, and FPR. Still nothing. It runs decently but smokes like a train. That's due to a lot of fuel in oil. Drives like crap. No throttle response. Replaced oil and filter, new plugs, getting fire all the way around. As I checked plugs for spark, I noted that each time I pulled the plug from the passenger Bank of the engine it would run from semi smooth to really rough. But everything from the drivers Bank of the engine did not make a change as I pulled the plugs. So that tells me the problem is isolated to the driver side Bank of the engine. What else could be the problem? Bad ECU? Bad injectors? I just don't see all three injectors going out at once unless there's something that I'm not aware of. So if anybody could enlighten me to help would be greatly appreciated! Thank you
Last edited by Blurrat120mph; 09-22-2018 at 04:16 PM. Reason: Misspellings
#3
#9
Like I stated before I know how to jump the connections with a wire but there are no codes stored because the battery has been dead for so long and I'm definitely not going to drive it around with gas in the oil. And I've already gone through one fresh oil change and less than 30 minutes just to have fresh fuel dumped into the oil about 3 gallons worth. Plus I don't want to damage the engine and blow out any seals by running it like that
Last edited by Blurrat120mph; 09-22-2018 at 07:41 PM. Reason: Misspellings
#12
RF Veteran
iTrader: (1)
Fuel injectors get 12volts with Key ON
The computer GROUNDS the injector to open it
Depending in the year, Batch Fire or Sequential injection, one injector wire shorted to ground could open 3 injectors on a V6 engine.
There should be a RED wire on each injector, its the 12v wire
Test the other wire, on each injector, with OHM meter, key on, to make sure it is not Grounded
If you have 6 different colored Ground wires you have sequential fuel injection, if there are only 2 different color ground wires then you have Batch fire
The computer GROUNDS the injector to open it
Depending in the year, Batch Fire or Sequential injection, one injector wire shorted to ground could open 3 injectors on a V6 engine.
There should be a RED wire on each injector, its the 12v wire
Test the other wire, on each injector, with OHM meter, key on, to make sure it is not Grounded
If you have 6 different colored Ground wires you have sequential fuel injection, if there are only 2 different color ground wires then you have Batch fire
#13
So connect the positive lead to the "other" wire and ground to the battery? If it's working proper, I shouldn't hear an audible beep? Also, so what you're saying is if the driver side grounds are all one color and the passenger side grounds are another color than that will be batch firing?
Last edited by Blurrat120mph; 09-23-2018 at 01:04 PM. Reason: Misspellings
#14
#15
RF Veteran
iTrader: (1)
#16
Injector tests results.
Fuel injectors get 12volts with Key ON
The computer GROUNDS the injector to open it
Depending in the year, Batch Fire or Sequential injection, one injector wire shorted to ground could open 3 injectors on a V6 engine.
There should be a RED wire on each injector, its the 12v wire
Test the other wire, on each injector, with OHM meter, key on, to make sure it is not Grounded
If you have 6 different colored Ground wires you have sequential fuel injection, if there are only 2 different color ground wires then you have Batch fire
The computer GROUNDS the injector to open it
Depending in the year, Batch Fire or Sequential injection, one injector wire shorted to ground could open 3 injectors on a V6 engine.
There should be a RED wire on each injector, its the 12v wire
Test the other wire, on each injector, with OHM meter, key on, to make sure it is not Grounded
If you have 6 different colored Ground wires you have sequential fuel injection, if there are only 2 different color ground wires then you have Batch fire
I then used a test light and tested wiring. With light connected to positive terminal on battery I probed all injector ground connections. Everyone of them pulse when engine is running. However, with key on the bad injector bank keeps the light on when probing grounds. Good bank doesn't light up. Disconnect the harness from ecu and light goes out on bad bank. I'm assuming this means the ecu is bad. Am I correct in my assumption?
#17
RF Veteran
iTrader: (1)
Yes, good testing
Pop the top on the ECU, should look like this inside: Ford EEC-IV
You can see the 3 Blue Capacitors, these would leak after 20+ years and cause ECU problems, the failed capacitor and the leaking of chemicals onto the circuit board
Less than $5 to replace these and clean up the circuit board under them
May not be the problem but FREE to have a look
Repair info here: http://support.moates.net/capacitor-...-ford-a9l-ecm/
Pop the top on the ECU, should look like this inside: Ford EEC-IV
You can see the 3 Blue Capacitors, these would leak after 20+ years and cause ECU problems, the failed capacitor and the leaking of chemicals onto the circuit board
Less than $5 to replace these and clean up the circuit board under them
May not be the problem but FREE to have a look
Repair info here: http://support.moates.net/capacitor-...-ford-a9l-ecm/
#18
Just want to say thanks for your help. It was quite frustrating as the the problem seemed to have been fuel related and tossed a new fuel pump and fpr to solve the issue to no avail. No fuel pressure as the injectors were dumping the fuel instead of opening and closing. You were the only intelligent response in this thread. I will update when I either open the ecu to check capacitors or order a new ecu. This means alot to a friend. It's his brothers truck. His brother passed away from overdose.
Last edited by Blurrat120mph; 10-07-2018 at 01:07 PM. Reason: Misspelling
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