Lift pump doesn't come on when key turned on

[Mathew Clausen]

OK - been reading about all these lift pump problems - then got to thinking that I hadn't noticed mine making the buzzing sound when you first turn the key on. Just checked - sure enough doesn't sound like it is running when I turn the key on. When they die do they quit running completely - or just the pump part quits? I will be getting some gauges to double check but my guess is it is bad. (could be a fuse or something I guess).

 

[Wheaties]

Mathew,



Not sure if you're turning the key on or bumping the starter. You need to bump the starter to get the lift pump to run. That is, you need to turn the key to start very briefly, enough to engage the starter but not enough to start the truck, then back to on and the lift pump should run.



I hope that is all it is. If you already know all this, then you may very well have a problem.



Good luck,

Matt

 

[otis]

I just had the same problem,dealer replaced dead lift pump under warranty. Take care of it asap!

Otis

 

[Mathew Clausen]

I tried that as well - but no luck. Mine used to run the lift pump for a second or so when you turn the key to the on position. I will be calling the dealer tomorrow.

 

[Bigsaint]

Try bumping your starter, like Matt said, for a confirmation. Sorry to say but there is no fuse directly linked to the transfer pump, it gets it's power through the ECM. The only fuse(actually, it's a relay) that I could find in my truck in the Power distribution center, under the hood, is related to the VP44. The lift pump runs whenever the engine is running. At key on (not bumping the starter) the pump gets a short signal from the ECM for maybe 1-2 seconds of juice. Bumping the starter ( allowing the starter to crank for a quick milisecond, stopping before the truck starts), will send a power signal to the transfer pump to run for about 15-20 seconds.



These pumps don't just quit all togther, they go out out slow. Chances are your's is not completely dead unless you are getting a hesitation/ stumble under hard accleration. Best bet is to hook up a FP gauge, even it's just a temp. unit, and take a ride.



EDIT... disregard the first line, you replied as I was typing.

Scott W.

 

[Wheaties]

I'd listen to Bigsaint. I've been following his lift pump 'adventures' and he's an expert!



Matt

 

[Bigsaint]

Expert, LOL . Well, I am pretty good at wasting Mallory pumps, and almost as good at replacing them .



Scott W.

 

[mbrolin]

On my 01HO ,when turning the key to the on position,the pump will run for a couple of seconds. This equates to about 6lbs of pressure which quickly drops off. This is startup pressure. When bumping the starter the pump will build up to over 15lbs of pressure.

 

[Rogue Ram]

Hey Mike...........

... ... . totally out of left field, what ever happened with your weird howling/whine noise under the hood?!?!?!?! (I'm dating myself here--)



Rogue

 

[pwr2tow]

Try switching your fuel relay with another one from the power distrabution box. I had a bad relay that would come on and off repeatedly, made my pump sound like there were marbles in it, When I switched the relay with another one the pump runs smooth and has good pressure. It's worth a try before spending money on a new pump.



Ron



EDIT:: try the horn relay, that way you won't loose power to anything important for startup procedure.