I could use a little help---hope someone out there can---
i have 89 f150 4x4 with the 5.0---the thing runs rich as well as surging problem---im running out of things to replace---ive done the following---new cap, rotor, plugs, wires, fuel filter,fuel pressure regulator, egr valve, o2 sensor, injectors flowed, replaced iac motor & valve, map senor, temp senor, ignition coil, air filter, no vacuum leaks that i can find---does anybody have any more idea or had a simular problem--thanks for any help

68cougarrrr

 

Welcome to FTE.

Sounds to me like you need to pull your codes.

http://www.midimonkey.com/~frederic/f350/eec-codes.html

There can be codes set even when the light isn't on.

How do you know it's running rich? The symptoms point to a fuel pressure problem, but you've already replaced the regulator. You may also have a sticking injector. Do you have a fuel pressure gauge that you can test the pressure and do a leak-down test with?

 

what thermostat are you running? i've got a '95 5.8l that i had a 160* therm. in. it would idle high to try to raise the coolant temp.

 

Are you sure you replaced the correct temp sensor? The ECT that the computer uses has 2 wires. The 1 wire sensor is for the gauge.

Is the exhaust stock? ie - is the O2 sensor in the correct loacation?

 

I know its running rich by the smell of the cat, black smoke---i assume the o2 sensor is in the correct spot(right before the 2 pipes join---all the exhaust is new---it has headers on it---as for the thermostat---im running a 180 degree---but this problem was before i changed it out---as for the codes---i have pulled them and one say i have a low egr flow---but with a new egr and i have cleaned out the carbon in the passage as best as i can---has made no difference---as for temp sensors---i believe i have replaced both of them

 

If this started, roughly, withthe header install then it sounds like the O2 sensor is in the wrong spot. If you've got a buddy with a stock truck measure how far down the eshaust his is and compare it to yours. It should be in about the same place, and with headers I would think it would be in the collector one one side.

Other possibilities are a bad o2 sensor, vacuum, and exhaust leaks before the o2 sensor.
Good luck and Merry Christmas!
Tim