lift pump want stop

[dripley]

i have a friend with an 01 5 speed. his lift pump will not cut off when you turn off the ignition. he has even diisconnected the driverside battery and it stopped, but when reconnected it comes back on. any ideas?

[MarbleCrusher]

First thing i would do is check the fuel pump relay-Jordan-

[Mopar1973Man]

First thing i would do is check the fuel pump relay

-Jordan-

Sorry that has nothing to do with the lift pump... That controls the VP44 power supply...

As for the lift pump the ECM is in direct control of the lift pump... So your ECM is fried... (Sorry!)

[dripley]

i was afraid of that.i didnt think that relay controled it. appreiate the help.

[old badger]

my Raptor lift pump has its own relay wired directly to driver side batt.could it be stuck?

[dripley]

his truck is still running the stock lift pump. it is run straight from the ecm. my AD is set the same as your raptor.

[MarbleCrusher]

Eww, yea i just assumed he had an airdog or FASS. In the case of a stock pump Im dead wrong.-Jordan-

[cummins2k]

Just assumptions but since they say the ecm can vary the duty cycle of the pump I would assume the h-bridge or supporting components in the ecm have failed. You could create a small harness to turn the lift pump on when the ignition is in the start/run position and just bypass the ecm completely. I am not sure what this would mean for fault detecting in the ecm though. Also it may cause hard starting since the lift pump would be running at max duty cycle when the key is in the start position.If you decided to get crazy with it you could make a small pulse width modulation board and install it in the truck. Pulling in a signal from the camshaft sensors signal wire would allow the module to know when the engine was running and when to increase the duty cycle. Just my 2 cents though. Just babbling.

[dripley]

i figure he can wire in a toggle switch and just flip it on and off real quickly and make it work:lmao:. it seems a waste to have to replace such an expensive part due to one portion of it failing. but with that part of it failing it probably is not long for the world any way.

[cummins2k]

i figure he can wire in a toggle switch and just flip it on and off real quickly and make it work:lmao:. it seems a waste to have to replace such an expensive part due to one portion of it failing. but with that part of it failing it probably is not long for the world any way.

Certainly is. The voltage regulator for the alternator is also in the ecm from what I hear. People talk about using an external voltage regulator when the factory circuit fails.

[dripley]

i believe the voltage regulator is in the PCM. have to check a wiring diagram.

[Mopar1973Man]

Certainly is. The voltage regulator for the alternator is also in the ecm from what I hear. People talk about using an external voltage regulator when the factory circuit fails.

i believe the voltage regulator is in the PCM. have to check a wiring diagram.

Yeah the voltage regulator is in the PCM... http://mopar.mopar1973man.com/cummins/2ndgen24v/wiring/2002-Dodge-Wiring-Pg1.jpg

[dually]

How old is the pump ?

[dripley]

thats hard to say and he has moved on to another job. he will be difficult to get hold of to ask.