Well, the fuel pump may be getting power to it dropped. The fuel pump relay is in the underhood fuse box. You swapped it around. But what about the base wiring plugs on the bottom side of the fuse box? The ECU turns on the fuel pump relay directly (supplies a ground). You could run a pair of wires from the output to the fuel pump, thru an inline fuse, and into the cab, and monitor it. If you see the volts drop as truck is dying, that could point you in a direction. You can look at wire harness for skint or melted spots; etc.

If you have a clamp on DC amp meter, you could run a loop from the same location and put test wire in series with pump, monitor current, current changes (goes low on open circuit, goes higher on obstructed pump or shorting out).

Chasing short duration events is not fun.

 

However, after more Red Bull, perhaps it is electrical in nature, but instead is something like the main relay (kills power to all sensors and an input to ECU) or the wiring from crank position sensor to the ECU.

 

thanks for your reply's. At this point the quick fix, gas+match= fixed

 

I recently "fixed" a problem I had been chasing for months on another piece of equipment - a pnuematic line was crossed over by a regular electrical cable. But vibration cause a pin hole to develop in the air line, where the cable rubbed on it, and it is little things like that which keep you up late at night throwing parts at it. We've had guys wth water on connectors, flooded ECUs. wire harness melted and grounding out, etc.

 

thanks for that sugestion, I had my truck smoked out twice and they didnt see any smoke.

 

check your throttle cable. if its loose tighten it to the right specs .5mm throttle cable 4-4.5mm cruise control cable.

 

wiggle the crap out of every sensor and wire to the ecu and the wiring harnesses. if you have a short it will happen after shaking it.

i have seen a few crank signals go arie from bad connectors at the ecu.