I have been told my computer could be burnt out. I recently bought a 1990 F150 XLT 351 4X4 long-bed with 160,000 miles. It makes about 13 mpg highway but with backcounty it is only 10-11 mpg. Smells rich. I had a mechanic hook up is $8000 computer tester. The switch-on but not running test showed some items to be repaired but the running test show "none" on all sensor, timing,etc readouts. The machanic said he never saw that before my truck. Later, I was told it could run in a "limp-home" mode with a bad computer but would not fine tune the systems when warmed to operating temperatures.

What should I do next to test this? I don't have a lot of money to pay dealer's prices or do I have a choice?
TIA
Bill

 

I would be looking at the wiring.
Often the connectors get condensation then corrosion built up.

Pull the plug from the computer and inspect it. If it looks good spray it with electrical contact cleaner anyway and try it again. Do the same for the harness on the drivers fender.

If you do have to replace it, get one from a wrecker. You will save a bunch.