I have a 2001 4.0 with a check engine light coming on once or twice a week, The codes are always lean bank 1 /lean bank 2. It seems like this happens when I let off the throttle.. and most of the time going down hill. I erase the codes and do not see anything for a few days. The only mod to the truck is an AirHog air filter. The truck has about 85,000 miles on it. Has anyone else had this occur? Any advice as to where to start is appreciated.

Thanks,,

 

just a guess but....since it happens when the gas is in the front of the tank (when going down hill or when you slow down) the problem would seem to be in the tank itself...no? pump(s)...anyone know how many are in ranger tanks?

 

I had that code once. I erased it and it never came back. Not sure what caused it.

 

Check your vacuum lines. Mine had a crack in one of the rubber elbows. look to the left of the oil fill tube thats where mine was.

 

Thanks for the Help and suggestions. I looked for a vacuum leak and found a line on the right side of the engine with a 5/8" formed 90 hose that was cracked. I bought a coolant hose that was preformed from the local parts store, timmed it to length. and so for it has not given the error codes again in the last two days.