drecu

Ok so my uncle has a 98 dodge dually and the truck starts and runs fine until about 2 mins after it is started the lift pump just turns off. so my question is... what controls the lift pump power and what could be causing it to turn off. if you shut the truck off and turn it back on it will work again for another 2 min and do the same thins.

Thanks for the input

BigIron70

The ecm controls lift pump, did you check voltage at lift pump? stock lift pump? Possible ECM, has two power circuits to pump (run & start circuit) The lift pump could be shorted so to protect circuit ecm shuts off power to pump.
Try another pump or use retrofit fuel pump (intank pump) which then uses a relay to power pump direct from positive side of battery. If 12 volts are present - Measure the resistance across the transfer pump. If greater
than 200 ohms or less than 0.2 ohms, replace transfer pump.
How to test pump
https://www.dieseltruckresource.com/....html?t=259251

FUEL TRANSFER PUMP (DIESEL) - 2 WAY CAV CIRCUIT FUNCTION
1 K135 18YL/WT TRANSFER PUMP POWER SUPPLY
2 Z11 18BK/WT GROUND

drecu

Hmm... maybe the start circut is all that is running and not switching to the run circut. i'm wondering if there is a fuse mabye or the ignition switch could be the culprit?

it has a raptor pump in place of the factory lp he told me all the wiring is the same though.

BigIron70

Do you have vehicle theft alarm?

drecu

nope no security stuff at all.

BigIron70

Do you have fuel pump wired into relay or into stock wiring? If into stock fuel pump wiring you maybe drawing more amps then ecm fuel pump driver is rated at, which would cause ecm to shut off power to circuit to protect wiring. The start run circuit is 12 volt but it is timed circuit which will turn off in 25sec. You might want to check how many amps your pump is drawing, maybe excessive.

BigIron70

If you have a Raptor 100 it is wired into a relay. Your Raptor has a limited warranty might want to check if it is covered still.
http://www.dkdiesel.com/manuals/pf/R...ual%202408.pdf