buzzing, humming noise when I switch the "ignition" key to the run position

[BBowers]

My 2003 ram ctd 4x4 quad can has 97,000 miles on it and makes a buzzing, humming noise when I switch on the key to the run position before I turn it further to engage the starter. It does this while I wait for the amber start light to turn off (grid heater?) and if I continue to wait to start after the light has gone off. Of course when I hit the starter I can't hear it over engine noise. Is it my lift pump? IS it failing? Truck makes good power and drives normally. Does not seem like it wants to smoke under moderate acceleration, even under +50 HP on my tripledog programmer, but will smoke under hard accel. my oil is super clean with 1200 miles on it, clear golden.

 

[Pawpaw]

That's the lift pump and it's normal. When you don't hear it before hitting the starter, there is a problem.



Bob

 

[CraigJones]

Are you sure its the lift pump ? I don't have the stock lift pump any more I replaced with walbro 392 pump and I get that vibration sound once in awhile. I'm wondering if its the heating element in the air intake.

 

[BDuffy]

the vacume pump on the 03 makes that noise till the vacume resivour is satisfied. if you hear it all the time there could be a vacume leak,sould only do it on the first start up of the day unless it sits for a while.