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carguyjosh, ASE Certified Technician
Category: Chevy
Satisfied Customers: 2172
Experience:  ASE certified , 16 yrs in field
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Chevy Monte Carlo: Liter fuel pump..left back fender well

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I have a 2000 SS Chevy Monte Carlo with a 3.8 Liter V-6. I changed my fuel pump yesterday and today i have a gas leak. It is coming from this little black box in the left back fender well. The black box has a wiring plug and a rubber hose connected to it. The hose looks like it might be a low preessure line or a relief line. When i turn the igination to the on position, it starts to leak faster from the box (maybe a relay or valve). Now that the car has been off for a couple of hours it has stop leaking. Please let me know what this box or valve is. Thanks Marty

The black box is your fuel tank vent solenoid.


It sounds like what has happened is that you swapped the fuel return and emissions vapor lines around.

I believe that both of these lines are 5/16 coming off of the fuel tank sending unit so it wouldn't be to difficult to do..


You will need to lower the tank back down and swap the fuel lines around. You will then want to pull the lines off of the charcoal canister and allow to fuel to drain.

The canister may need to be replaced in the future...


Thanks, Josh

Customer: replied 7 years ago.

So after i put in the fuel pump i went to go fill up my car. As i was filling it up (the car was almost empty) the gas pump kept clicking off. If the lines was in the wrong positions would it cause the gas pump to click off while trying ot fill it.


What has happened is that you have filled the venting system with fuel.

The vent system is designed to allow the fuel vapor pressure to escape while your filling the tank. With the vent system being full of fuel, the vapor pressure can not escape from the tank properly therefore it shuts off the pump.


Once you return the lines to their proper positions and drain the fuel out of the canister, you should be all set....


Thanks, Josh

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Customer: replied 7 years ago.

Can you send me a diagram of how thefuel hoses and how to remove the fuel canister to drain it please. Also all of your information has been right on thanks

I will do some searching to see if I can find a diagram for you. The diagrams are not very good