fuel filter replace: how much leakage? siphon thru pump?

[mike_2001]

Hi.

 

I started replacing the fuel filter on my 2001 suburban this morning. I relieved the fuel system pressure by removing the relay and cranking, and then began to remove the filter. I put a catch can under the filter, and it leaked maybe 1/2 gallon before I tightend the connections up again. The line coming from the tank is the culprit. I suspect it is siphoning thru the fuel pump.

 

If it has any bearing on the question, my charcoal canister and associated hose have been plugged for some time now (code P0446), to the degree that I have had to leave the gas cap slighly open to permit venting. I guess if it is siphoning, maybe if I tightened the gas cap tight, it would stop the siphon effect.

 

Has anyone ever seen this before?

 

[txab]

Best thing.... change the filter quickly. Wear safety glasses. Plan to get wet with gas somewhat

[Doug_Scott]

Whenever I was going to change a part that required me to lay down, I would gather all the tools necessary, all the parts necessary, and make just the one trip under the vehicle. In other words, I would not leave the system open while I went to get something.

 

And yes, it will siphon fuel out of the tank. The pressure part of your post is probably going to be a bit different to what you are expecting. The fuel caps usually have a check valve in them that will allow air into the tank, but not vent fumes out of the tank. Due to this, tightening the cap should not stop the siphoning unless the one way valve is designed to hold partial vacuum (less than atmospheric pressure) in the tank. I have never really looked into the flow of the canister, or what each line does during normal operation to be able to comment on its effect to pressure in the fuel tank.

[mike_2001]

Thanks. I need to give it another try when the weather improves a bit.