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Hal, Chevy Master Tech
Category: Chevy
Satisfied Customers: 1031
Experience:  ASE and Chevy Master , 31yr Dealership exp,
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chevrolet: 01 duramax has air leak in fuel system have replaced

Resolved Question:

01 duramax has air leak in fuel system have replaced filter housing did not fix where do i go now
Submitted: 5 years ago.
Category: Chevy
Expert:  Hal replied 5 years ago.

Hi my name is XXXXX XXXXX Your complete satisfaction is my goal. Please provide as much information about your concern as you can.


What is the reason you feel there is air in the filter? Is the engine hard to start hot? or after it sets overnight?


Do you have to pump the primer to start?


Most air leaks that enter the fuel filter , are cause by the bleed screw, and the WIF ( water in fuel ) sensor seal at the bottom of the filter. ( no more than 1/2 turn from contact or it will deform the seal.


These engines are know for injector issues that cause a hard start that can act like air in the fuel, and priming the filter will get the engine to start.


So I'm just trying to get a good idea of the condition that is occurring, so I can best help you repair the condition.

Customer: replied 5 years ago.

after it sits for awhile it will start @ run for about 30 seconds @ die if i crank it long enough it will restart but i usually pump the primer @ it obviously starts much easier. if i park it nose down it will start @ not die. i have replaced the filter housing twice @replaced the fuel lines connected to it

Expert:  Hal replied 5 years ago.

Thank you for that information. Have you checked the fuel lines from the tank? I have seen air leaks develop at the hoses from the frame to pipe connections at the point the lines go up and over the transmission and also at the point the lines connect to the engine.


You can get a 1/2 " clear line and connect it to the inlet side of the filter to see if air is entering the system before the housing. Then it will be necessary to verify the lines from the tank to the engine.


I have seen a couple of sending unit hose leaks inside the tank. There is no pump in the tank, but there is a flexible plastic hose that can develop pin holes and cause air to be drawn in.

Customer: replied 5 years ago.
i have replaced the sending unit in the tank @ i have looked at the lines from front to back dont see anything but i know diesel wont necessarily leak out but air can get in so how can i tell if they are bad also when i pump the primer it sounds like i can hear a hiss but i can't find where its coming from
Expert:  Hal replied 5 years ago.
The primer will only pressurize from the filter to the injection pump. You can use a cooling system tester/pump to pressurize the fuel lines from the engine back. Just look for a small amount of dampness at the hose to pipe fittings. All connections should be dry. If they are wet at all. Replace the hose.
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