1995 RRC SWB (3.9): Truck has been running very rich, can easily smell it, and gas mileage has gone from 14/15mpg to 9/10mpg around town. Truck will sometimes die at idle, choking itself out due to rich, then be very difficult to restart, requiring full throttle to allow more air and drilling starter for a minute or so. At times truck will have to be left where it is to sit for an hour then will restart fine. This has gotten progressively worse now and truck will not start at all. My guess is plugs are completely fouled, so I'll get those replaced tomorrow. My concern is what could be causing this, and this is what I have done so far:
1) Swapped ECU.
2) Checked the Engine Temp Sensor for the ECU at various temps, all ohm reading are right on spec.
3) Checked spark at plugs and coil lead, very strong spark.
3) Swapped out the AFM.
4) Fuel Pressure is around 40PSI when cranking.
I've thought about leaking injectors, but I have had that problem before, and that usually results in very difficult starts after letting truck sit about 15min as the injectors leak fuel in hot engine making hard to start.
Also, Once I get the truck running again, even though the ECU Temp Sensor has good readings, I'll also check the readings back at the ECU to make sure there is not a wiring problem.
I'll also check the O2's as well, may just replace them.
Anything else you guys can think of?
Tim
1) Swapped ECU.
2) Checked the Engine Temp Sensor for the ECU at various temps, all ohm reading are right on spec.
3) Checked spark at plugs and coil lead, very strong spark.
3) Swapped out the AFM.
4) Fuel Pressure is around 40PSI when cranking.
I've thought about leaking injectors, but I have had that problem before, and that usually results in very difficult starts after letting truck sit about 15min as the injectors leak fuel in hot engine making hard to start.
Also, Once I get the truck running again, even though the ECU Temp Sensor has good readings, I'll also check the readings back at the ECU to make sure there is not a wiring problem.
I'll also check the O2's as well, may just replace them.
Anything else you guys can think of?
Tim