Ranger running rich

[SoloSat]

I have an interesting problem with the fuel mixture in 1988 Ranger. It starts and runs easy till it warms up in a mile or two. It runs rough at cruise in the mid range or low range and blows black smoke out the exhaust. If you press down on the gas, it jumps right out there and accelerates great. This did the same thing about two years ago and a full tuneup didn't resolve it. I changed the fuel filter and the bypass valve. I checked the fuel pressure and it was a tad off so I changed the fuel pressure regulator. It still ran rough at cruise speeds but would smooth right out and haul butt if you pressed down on the pedal. I thought I may have had some bad injectors so I poured some Chevron fuel injector cleaner into the tank and Tah-dah, it smoothed right out and ran great for the past two years with some additive every tank full or so. Now that it's reoccured, I changed the fuel filter and checked the fuel pressure. It's still good at 40 psi. No help! While driving, it seemed to smooth out if I restarted the engine. Now I turn the key off on on while driving when the rough episodes begin and it smooths out for a few miles. Any ideas?

 

[freedom5]

Have you changed the O-2 sensor?

 

[alwaysFlOoReD]

^^^ this is my immediate reaction too, but there can be reasons for the o2 sensor going bad other than being old. Also check the temp. sensor, if its not working, the ecm thinks the motor is cold and keeps feeding a rich mixture when the motor doesn't need it. Also maybe a leaking or stuck injector?

Good luck,

Richard

 

[SoloSat]

Thanks for the feedback.

Gents, thanks for the feedback.
After reading quite a few Threads of the same nature, I have also deduced the O2 sensor needs attention. I think the giveaway is the key turning it off and on and the engine smoothing out for a spell. I also will reboot the fire control by removing the negative battery terminal plus look into a small coolant leak in the heater hoses. The coolant level is not all the way to the top after it warms up. I've been filling it and looking for the source but the spray is from a small source and hard to locate right after pulling over and opening the hood. I think the coolant temp sensor is not immersed in coolant to give an accurate temp reading but the gauge on the dash shows a normal temp and not cold. I may have to pressure up the coolant system and watch for the source as I do it. The level only drops about a quart or less and you can see it about 5 inches down in the radiator. It seems to hold the fluid till I come to a complete stop and shut it down. Then I see vapors coming from under the hood but the leak is quite small. Odd Huh.

 

[PGHFord]

Gents, thanks for the feedback.
After reading quite a few Threads of the same nature, I have also deduced the O2 sensor needs attention. I think the giveaway is the key turning it off and on and the engine smoothing out for a spell. I also will reboot the fire control by removing the negative battery terminal plus look into a small coolant leak in the heater hoses. The coolant level is not all the way to the top after it warms up. I've been filling it and looking for the source but the spray is from a small source and hard to locate right after pulling over and opening the hood. I think the coolant temp sensor is not immersed in coolant to give an accurate temp reading but the gauge on the dash shows a normal temp and not cold. I may have to pressure up the coolant system and watch for the source as I do it. The level only drops about a quart or less and you can see it about 5 inches down in the radiator. It seems to hold the fluid till I come to a complete stop and shut it down. Then I see vapors coming from under the hood but the leak is quite small. Odd Huh.

If you got one of those fittings in your heater line to hook a garden hose to, to flush the system here and there, look there. For the longest time on my way to work I could smell coolant, but could never find the leak, last week when I was replacing my TFI and idling the truck from cold to warm, darned if there wasnt coolant leaking there, tightened down the hose clamps some more, fixed issue.