Engine/Transmission (1998.5 - 2002) lift pump wont run

[JFringer]

my lift pump is not runing at all. it ran fine all day then i go to leave for work and nothing. i can bump the starter still nothing. all wires in good shape. any one got any ideas to what it could be. what should i check first

 

[JFringer]

come on now. im trying to get this truck on the road by tomorrow morning

 

[CPavlic]

I would start with checking power and ground to the pump first and go from there.

 

[JFringer]

it has power about 9 volts what should it be. it quit a few weeks ago going down the road i got out and jiggled the wires a little bit and it started runing again. so i know its a short somwhere but im terrible when it comes to electric things and i dont know where to start.

 

[Ram4Sam]

Since you have power, the lift pump probably took a dump on you.



Sam

 

[JFringer]

you would think that but it will run just fine sometimes and other times you start the truck and wont have any fuel pressure cut the truck off and bump the starter nothing.

 

[Steve Robinson]

Do you have a stock pump or have yoi installed an after market unit like a FASS?

 

[DavidC]

9 volts sounds low, although I have never checked I would think 12 volts. How did you measure voltage, across the plug or from the plug to battery negative?.

Could be a bad ground on the harness. For a 99 the ground is blk/wht and the positive is yellow/white. The power comes from the ecm. The best way to check power is with a test light as it puts a load on the wire where a meter will register something even if the wire only has one strand left (although it will not handle the amperage to handle the load). Also reading across the unplugged pump with an ohmmeter should show some kind of resistance. If it does not have resistance it may be in the pigtail to the pump or internally to the pump.



Dave

 

[Bob4x4]

The pump runs off a pwm(pulse width modulation) signal a volt meter will show you an average. From what you describe I would replace the connector at the pump first. You may have some strands that have fatigued and make and break.

 

[MChildress]

If you find the pump took a dump and your pretty much stock. Geno's has a Fass pump that is pretty much a drop in or you can move it to the frame. Put one in for a friend of mine the other day and its not too hard on the pocket book.