Truck cranks but not starting

Hi,

This doesn't sound like a fuel pump issue. If you hear the fuel pump come on, then we can assume it is ok for now. We may need to come back and check it but let's move onto spark first. The reason is, a fuel pump that shuts off normally does not cause a quick shut off as you described. It sounds like the ignition is cut off causing it to shut off.

I would pull a spark plug and hold it against the block and crank the engine and see if you have spark.

Plus, the fuel pump fuse is hot at all times so it makes sense that you have power even with the key off.

Let me know if you have spark and we can go from there. Thanks

Sorry, I misread that. I thought you said you did hear it come on. This could be a relay if you have current going to the pump but the pump does not come on. You should have another relay in the box that is the same. Just try swapping it with another and see if the pump comes on. If not, the best way to check for spark is to pull a plug and hold it against the engine block while the engine is cranking.