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Lift pump noise

drocker

drocker

New Member
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Location
Kansas
I have been reading how you are supposed to hear your lift pump running when you shut off your vehicles for a few seconds. Well I have been trying to hear mine after I shut it down and I finally heard it. Couple of questions:

1) can you hear it running while the truck is running?
I cant hear mine

2) is it supposed to make a humming noise?
it sounds like a marble rattling in a spray can but not as loud

3) when I start my truck it takes about 3 to 5 seconds of cranking the starter before it starts. Maybe a second less is plugged in. Then it idles really low like it is stumbling for about 2 to 3 seconds and then it smooths out and idles fine. Is this normal or signs of something else?

It just seams that being fuel injected, it wouldn't start so hard and then idle rough for those few seconds. So I guessing the LP but need some expertise with this since I am new to diesels.
 
1 I can't hear mine either

2 same as mine

3 Could be IP timing also try disconnecting ect before starting cold see if that makes any diff. Also just because you can hear lift pump running doesn't mean it's pumping. Put a pressure guage on the drain tee and verify pressure. 94s don't run the lift pump during wait to start but do during cranking. Good lift pump write up in the stickies
 
The easiest test is to open the t-valve and see if there is fuel coming out while engine is running. If not, put 12V direct source and see if you can get fuel. If yes, then OPS is bad. If both no, then LP and/or OPS both are bad. Pass/fail test. Then we can test the pressure if both passes.

Hearing it does not mean it is pumping and pumping does not mean it will be heard.
 
^ started truck and opened the T valve. Fuel came out but it sure looked like a lot water. It smells like diesel though. Truck was still hard to start. I am wondering if maybe some of the glow plugs might be bad. I need get my ohm meter out to test the ECT though and see what it shows. Now if anyone can tell me where it is.
 
Last edited:
The ect your looking for is in the coolant crossover. There are 2 one in the head for the dash guage and the other for the ecm. Even if you test it unplug it next time you do a cold start. It does 2 things it makes the pcm think it's -40 and it will affect the cold advance.
 
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