Hey guys needing some help on my 2001 f250 with 5.4 it has me puzzled at this point.most of the time when you switch the key on the fuel pump comes on and the truck starts,but every now and then when you switch it on the pump won't come on and the truck will start then shut back off you can cycle the key a few times and the pump will come on and start n run fine the pcm and fuel pump relay check out fine I replaced the fuel regulator also.fuel pressure reads 40psi when switched on and 30 when running.any information is greatly appreciated as I'm going crazy over this issue

 

Most likely the pump is shot. The bearings have a flat spot on them and well you know the rest. That happens alot ....also a wire issue...Next time you don't here it have someone bang the tank to see if it can jolt it...

 

Is the pump making any noises? It could very well be as 99f350sd said, that the bearings in the pump are shot and you need a new one. A pump is only about $100 anyway, so it wouldn't be too bad.