Can a person rewire the lift pump to operate when ignition is on instead of thru. the computor?

Are you having problems with your truck starting? I suppose you could wire your lp to an ign source but unless your having issue I dont think theres any benefits to it

I've heard of direct wiring for testing but VP44 likes a few seconds prime then not fuel pump running until it starts. My AD150 is wired through a relay with the OEM power acting as the relay trigger.

I've heard of direct wiring for testing but VP44 likes a few seconds prime then not fuel pump running until it starts. My AD150 is wired through a relay with the OEM power acting as the relay trigger.

Pump was not working so I bought a new one. Before installing I tested it .Not operational. Tested power sorce and have no power. Because of where the wiring harness is located I thought that I would save my self a lot stress and install on igni. side. Is there any one with complete wiring diagram or know where I can get one for a 98.5/ 5.9. It would be greatly appr.

I'm sure there's a diagram here somewhere. My OEM lift pump stopped... truck stopped. My mechanic found a dirty connection I think on the passenger's side a connector a few inches from the battery. Clean all the terminals & grounds.

You "could" direct wire the pump but it might create starting issues as well. VP44's injection pumps don't like the excessive pressure during starting. This why the ECM controls the lift pump and has a 50% duty cycle during cranking then when the key is released it flipped to full 100% duty cycle. Then there is a safety issue involved too. Back in the 12V relm all the pumps were mechanical so when you the engine dies so does the lift pump. But now with a keyed hot lift pump if you where in a accident and trapped in the truck the lift pump could still be pump fuel into a engine fire and be deadly. Hence why the ECM controlled lift pump so if the crank/cam sensor no longer sees RPM's the lift pump shuts down as a safety measure.Food for thought...

You "could" direct wire the pump but it might create starting issues as well. VP44's injection pumps don't like the excessive pressure during starting. This why the ECM controls the lift pump and has a 50% duty cycle during cranking then when the key is released it flipped to full 100% duty cycle. Then there is a safety issue involved too. Back in the 12V relm all the pumps were mechanical so when you the engine dies so does the lift pump. But now with a keyed hot lift pump if you where in a accident and trapped in the truck the lift pump could still be pump fuel into a engine fire and be deadly. Hence why the ECM controlled lift pump so if the crank/cam sensor no longer sees RPM's the lift pump shuts down as a safety measure. Food for thought...

Thats what I thought. Is there a drawing that is available where this power sorse comes off the ECM(would make life a lot simpler. I would like to thank you for the info.

Yes there is...

i have my lift pump direct wired with a switch under my dash I start my truck and flip it on i have been running it that way for 4 years. i was having issue with the power provided from the computer on the side of the block. It is a 12v lead that feeds the lift pump. I just have a inline 20 amp fuse so if a for get to turn it off and get out of the truck and leave it on it blows the fuse ad doesn't damage my pump. It work just like a normal lift pump just remember start your truck and turn on pump and turn it off then flip switch. I haven't had any issue starting it year around for the past 4 years. I have seen people use the ignition to turn on a relay to start the pump but i am a simple guy a prefer simplistic. If my lift pumps not running the pump bad, fuse, Wire broke

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I brought my power out of the many fuse panel under the hood. I used the main power post

You "could" direct wire the pump but it might create starting issues as well. VP44's injection pumps don't like the excessive pressure during starting. This why the ECM controls the lift pump and has a 50% duty cycle during cranking then when the key is released it flipped to full 100% duty cycle. Then there is a safety issue involved too. Back in the 12V relm all the pumps were mechanical so when you the engine dies so does the lift pump. But now with a keyed hot lift pump if you where in a accident and trapped in the truck the lift pump could still be pump fuel into a engine fire and be deadly. Hence why the ECM controlled lift pump so if the crank/cam sensor no longer sees RPM's the lift pump shuts down as a safety measure. Food for thought...

As for the safety issue mentioned above, this is a very important point. Mike, wouldn't there be a safe way to hook up the pump direct if you used the Alternator as the relay activation and then run off the main battery fuse for power. I think Dripley hooked his lift pump direct to the Alt without a relay can't remember if that is safe or not.

Actually I just got done making a wiring diagram for a 12V 2nd Gen to use a oil pressure switch and both start and run leads from the ignition. It a crude design and untested at this moment but you welocme to try it.

trigger relay.pdf

As for the safety issue mentioned above, this is a very important point. Mike, wouldn't there be a safe way to hook up the pump direct if you used the Alternator as the relay activation and then run off the main battery fuse for power. I think Dripley hooked his lift pump direct to the Alt without a relay can't remember if that is safe or not.

I used the alt for a power source, but it still goes thru a relay triggered by the wiring harness for the oe lift pump.

I used the alt for a power source

Simpler version use the power studs in the PDC box that the alternator fuse is hooked too. Then find a body ground else where not the battery ground you have connection that won't corrode...