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cummins man 7

loud noise seems to be coming from lift pump

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I have a 99 3500 mostly stock and im not to sure what this noise is or why its this loud when i turn the key on. It seems like something with the lift pump but it stays on for awhile and is very noticable in the cab then turns off. The trucks start fine and i have a crappy electric fuel pressure gauge and when it makes that noise its at atleast 25# and then i start it and it stays right around 24-25#. I have a few videos showing the noise and the gauge but none of the noise right when i turn the key forward without bumping. It sometimes comes on for a few seconds but lately has been coming on for the full 20- 25 second cycle without bumping the starter. Can you tell me if its supposed to be this loud and why it would cycle without bumping the starter only turning the key on. Also why the pressures so high? Heres the videos http://s1226.photobucket.com/albums/ee416/cumminsman7/

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some of the guys here have electric gauges and some us have mech gauges, as long as they are installed properly they both work very well. does your pressure normally run as high as 24 to 26 psi? the best i ever managed out of a stock lift pump was 10 or 11 psi. the excess noise could be the pump going bad, though the pressure reading is strange for a bad pump. is the pump a oe pump?

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I tend to agree with Dripley... I think your pressure gauge has a damaged sender being the pressure is so high. Also there is no snubber or needle valve on the sender the gauge should not snap to 25 PSI like that that shows your not dampening the water hammer so more than likely the pressure gauge is wrong and damaged...

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some of the guys here have electric gauges and some us have mech gauges, as long as they are installed properly they both work very well. does your pressure normally run as high as 24 to 26 psi? the best i ever managed out of a stock lift pump was 10 or 11 psi. the excess noise could be the pump going bad, though the pressure reading is strange for a bad pump. is the pump a oe pump?

The truck is new to me and the gauge was on there and Im not sure what kind of pump to be honest. Idk why the lift pump would run a full course just turning the key before bumping the starter? I noticed i had to charge the batteries so maybe low voltage and also noticed it was blowing black smoke before on start up then all this started and it turned to blue and i believe its because the lift pump ran so long before i started it up so it was all the extra unburnt fuel coming out. Another thing i have the bed off because Im replacing it and i broke the filler neck so i took it off so the two rubber hoses that go into the tank are wide open so maybe the air pressure causing something weird? Plus i think the fuel pressure gauge is shot to be honest. What do you think about it all?

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ECM controls the lift pump so I'm not sure... :shrug: As for the truck I'm sure it can be fixed... But what I would do is start from the ground up and change every fluid and filter on the truck ASAP. This way you know whats in it and the condition. As for the fuel I would run that tank down as low as possible and drop the tank and check the contents for water, dirt, etc... Really hate to see you fuel system filled up with road dirt... But yes get the hose changed too...

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ECM controls the lift pump so I'm not sure... :shrug: As for the truck I'm sure it can be fixed... But what I would do is start from the ground up and change every fluid and filter on the truck ASAP. This way you know whats in it and the condition. As for the fuel I would run that tank down as low as possible and drop the tank and check the contents for water, dirt, etc... Really hate to see you fuel system filled up with road dirt... But yes get the hose changed too...

Thanks for the replies and I will do that and change all fluids and filters

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my new air dog bumps on when i turn the key on for a 1/4 second. i dont know wether the othe 2 lift pumps i have had did that or not. i dont know why yours is coming on for so long.my 02 has a schrader valve on the fuel inlet of the vp44 and if you have or know someone who has a test gauge youcan check your pressure with out having to redo your current fuel pressure gauge. while you have the bed off check and see if you have an in tank pump. you will either hear it running in the tank or on the side of the block just rear of you fuel filter canister. it would be very easy to put a good fuel system on while the bed is off, if you have the luxury of time.

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