91 bronco, 5.0, eec ~ Fuel pump Cycling
My 1991 Full Size Bronco with 5.0 L. and 4 wd. has the following problem that the local mechanics have not heard of: Help!
When turning the ignition key the fuel pump should cycle for about 2 seconds and then cut off untill started... My fuel pump continues to run when the ingnition key is turned. The vehicle will not start when this happens and it seems to happen after the vehicle has warmed up for 30 minutes. It does not help to disconnect the battery and re-connect. If I let it sit for a week and go to start it is back to normal: short burst of fuel cycle with turn of key, and then she starts up fine. After 30 minutes it seems to sputter and the exhaust looks like all of the sudden it is burning rich ( heavy carbon smoke). When I try to start again I get the tell tale sign of the fuel pump continually cycling instead of a short burst. What is strange, a week later it may start again.
I have changed the relays, o2 sensor to no avail. Before I replace the computer I wanted to know if their is somethingelse causing this.