1994 Ranger 4×4 4.0l indicates running rich on all six cylinders idles rough gulping fuel.

[imjustrick0904]

My 94 Ranger was running just fine then one day developed a very rough idle and misfires. Ive replaced plugs wires and coil pack no help. Cleaned the MAF sensor and IAC. All were no help. No vaccum leaks, No fuel in FPR vaccum line and no vaccum leaks detected using carb and choke cleaner at as many possible vaccum leak areas I could think of. Oh and no CEL. All six plugs indicated a rïch running condition.

Update...I removed PCM after testing with a scan tool. 513 DTC indicating internal voltage failure in the PCM. Upon removing the cover I found all three electrolytic capitors were leaking or damaged. Also found a blown resistor on the positive leg of the 10uf 63v capacitor. Bought a repair kit on Amazon and found a local electronics repair shop to do the repair. Only took him an hour and cost me $50. Installed back in the truck and still got the 513 DTC. But the truck seemed to run much better but still with a rough idle. I turned the truck off waited a couple minutes turned truck on without starting and used a stethoscope to verify pump was running in the tank and it was. Went to the fuel rail immediately after turning off the key and pushed the pin in on the fuel rail schrader valve. Fuel came out but was definitely not at 30+ psi. Only spurted out about two inches for less than a second. Am I looking at a bad pump or clogged fuel filter? The low pressure would explain the rough idle.

 

[rumblecloud]

Air cleaner and inlet clear of any obstructions?

 

[imjustrick0904]

Air cleaner and inlet clear of any obstructions?

Yes.....I also cleaned the throttle body

 

[rumblecloud]

Odd that there are no codes...
Fuel pressure is good and consistent?

 

[imjustrick0904]

Odd that there are no codes...
Fuel pressure is good and consistent?

Thats next to check. Fuel pump and sending unit were replaced by previous owner shortly before I bought it. Not sure about the fuel filter. Truck sat for three years before I bought it. Ive put over 500 miles on it since I got it up and running with no issues til now.

 

[sgtsandman]

Since you mentioned a carburetor, have you looked at the choke to make sure it's operating correctly?

 

[imjustrick0904]

Since you mentioned a carburetor, have you looked at the choke to make sure it's operating correctly?

No carb it is a fuel injected 4.0l

 

[sgtsandman]

No carb it is a fuel injected 4.0l

Carb cleaner. My bad. LOL

 

[imjustrick0904]

Update.....upon further examination there is alot of fuel in the oil pan. I also cannot get into the clear flooded engine mode.

 

[sgtsandman]

Hopefully, it's just a leaking/bad injector. You might try pulling one at a time and cleaning them and see if you can save/fix the problem cheaply. Look at the wiring that connects into the injectors while you are at it and see if there is a wire issue. Someone will be along with more detailed instructions and where to go from there if needed. Thankfully, I haven't had to mess with a ground vehicle fuel system much.

 

[rumblecloud]

Update.....upon further examination there is alot of fuel in the oil pan. I also cannot get into the clear flooded engine mode.

I'm confused (in a lot of different ways). You said "fuel in the oil pan?" Not ON the pan, but IN the pan?
Help me out here.

 

[imjustrick0904]

I'm confused (in a lot of different ways). You said "fuel in the oil pan?" Not ON the pan, but IN the pan?
Help me out here.

Excess unburned fuel mixing with the oil in the pan. Leaking down past either a valve or rings.

 

[gaz]

In an ohv 4.0L, I would expect it to be the valves. When I inspected my donor 4.0 valve train, they were unbelievably carboned up, it needed the valve seats recut; it must have drank a quart of oil/month.