power to lift pump problems
 

ok time to start again. so my problem is some days i can go out and start the truck and drive it all day with no problems and other days i can go out and start it and fifteen seconds to whenever later the power to the fuel pump gets shut off. it happens very randomly. i have checked the lift pump and it works great. i have got codes 0234,1693,0234,0230,0382 over the last month of trying to find out what is causing my problem. can someone please help

P0230 Transfer Pump (Lift Pump) Circuit
Out of Range
Problem detected in fuel transfer pump circuits.P0234 (M) Turbo Boost Limit Exceeded Problem detected in turbocharger wastegate.P0382 (M) Intake Air Heater Relay #2 Control
Circuit
Problem detected in #2 air heater solenoid/relay circuit
(not heater element)Sounds to me you may want to check the pump relay:humm:I would replace it cheap fix if it still does it the lift pump get it voltage from the ECM.The reley is under the hood in the fuses box.Check the battery voltage must be greater then 11.5 volts. Hope this helps.

i did switch the relays in the fuse box and it still does it. i lose the voltage to the lift pump.

Measure the resistance across the transfer pump. If greater than 200 ohms or less than 0.2 ohms, replace transfer pump.Batterys are good correct?:humm:

ok i measures the resistance across the transfer pump which is the same as the lift pump? 1.6 ohms and the battery's are 12.55 volts

Yes - transfer pump = lift pump

The only sure way I've found to check the lift pump is working properly is to hot wire it right to the battery and go for a drive. If you still have the problem you know the LP is either going bad or is bad, if you don't have any problems then it is in the electronics someplace. Probably the computer since it is what tells the LP when to run via the trigger wire. You could even run it through a switch in the cab and the next time it starts actin up just flip that switch to see if it fixes the problem.

The fuel pump relay is the relay supply to the VP44 NOT the lift pump.

The ECM supplies the lift pump curcuit completely. So either the lift pump is going south or the ECM is going. There isn't anything in between them...:w2:

i have hot wired the lift pump and it does fine. does that mean it is the ecm?

That's why... The ECm doesn't see a lift pump present... :ph: