I have a 93 Bronco with a 5.8. It runs fine most of the time. Once in a while it leaves me stranded at start up and I don't know why. Usually my truck will display the check engine light while running or with the ignition on, it always has and it has always run fine. The problem occurs only sometimes when the ignition is turned on. You don't hear the fuel pump start up or it will engage for about a half second instead of a whole second or two and quit. When this happens, I dont hear the pump engage but I do hear a click under the hood. The battery light and all other gauges (with the exception of the check engine light) power up and the engine will turn over fine but won't start due to lack of fuel. After waiting a while sometimes for an hour or more,the fuel pump and the check engine light come on simultaneously and it starts right up. Fuel or electrical, any suggestions?

 

I would get a code reader on it and check the codes. The fuel pump circuit is the obvious problem from your description, but if you pull the codes you may find you have a power problem to the computer or an ignition module problem. If the ignition module goes bad, then the computer does not get the pulses from the dist, and it thinks the engine is not running, so it does not activate the pump circuit. I would see what comes up.

 

Sounds like your PCM Power relay (or it source or feed) may be intermittent.

The lack of the CEL when the fault occurs indicates that the PCM is not operating at the time, most likely due to a lack of power. The PCM has to be "online" in order to switch the fuel pump relay on.

Other components that cause the exact same symptom include your ignition switch, the PCM power diode, or a bad connection at any one of these components or at fuse "U" in the underhood fuse panel.

Steve