I have a 92' Ford Ranger with 2.9 V6. I have had this on and off starting problem for over three months now. I think I am close to an answer. Starter will crank strong but engine will not start. Then I jump it or hook up my engine starter and it fires up. Battery, battery cables, starter motor, alternator, alternator belt, solenoid, pressure regulator, fuel filter (new) spark plugs, spark plug cables, cap and rotorare all ok This problem may disappear anywhere from 2 days to 2 weeks, and then reappear.

When the engine refuses to start, I don't hear the "buzzing" sound when ignition key is turned. I am told this is fuel pump energizing.

It has to be one of these two possibilities:

fuel pump (mechanic did some cursory tests, and said 1 year old fuel pump needs replacing)
wiring leading to fuel pump (electrical short?)

I thought about sugar or other foreign matter in fuel tank, but engine runs really well. Can anybody help me narrow this down even further?

Thanks,
Dave

 

With the key initially turned to the "on" postition only (not going to "start"), the buzzing should stop after 2 or 3 seconds. I think this is to prevent over-pressure, then the pump resumes when you start the truck. If you don't hear the sound when you first turn the key on, then the pump isn't running. I would suspect the fuel pump relay over the pump itself due to the intermittent nature of the problem. You may even find an identical relay in the power distribution box and swap it with the fuel pump relay to verify the problem exists there.