Scotty,
I have a 1991 Ford F150 4.9l I6 300 engine with 73,000 miles. It is running poorly and getting poor gas mileage. I have done the following things.
- 4 Years ago (but only 20k miles) new pcm, new spark plugs, cleaned fuel injectors, new EGR
- Last 3 months, new air filter, TPS, MAP sensor, O2 sensor.
- Backpressure check on catalytic convertor says its ok.
When I put in new O2 sensor it started running better and doesn't die as much. It seems to idle fine but when I press gas pedal it hesitates and does not accelerate properly. I can't figure out what is wrong! What do you think?
The problem is so old OBD2 scanner doesn't work on them and you'll get very little information. So you got in two things like pressure test the fuel pump see if that's weak do a compression testing of the engine see if the catalytic converter is clogged up that can be tested with a pressure gauge. Often it is a fuel pump or clogged fuel filter though
Backpressure check says catalytic convertor is fine. I will check fuel filter and fuel pressure next. Could a vaccum leak cause a problem?