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Michael Moore
Category: Chevy
Satisfied Customers: 2956
Experience:  ASE Master/GM WORLD CLASS/GM Master/GM ASEP/Dodge Gold/Mazda cert.
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I have an 04 silverado and I am having problems putting gas

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I have an 04 silverado and I am having problems putting gas in it.I have been told it is the evap system that causes this. What is the best way and cheapest way to fix this problem? Can the evap system be bypassed?Thanks.
The problem is most likely in the evap system, you can not by-pass this system. This system soaks up fuel vapors from the fuel tank and when the engine is running, it pulls these vapors from the evap canister so you can burn then instead of venting then off.
The problem is the vent valve in the system. This valve allows air in the fuel tank to vent out. The air goes thru the evap canister where carbon soaks up the fuel fumes, then out of the vent. When the computer checks the fuel system for evap leaks, it closes this vent and puts a vacuum on the fuel tank and checks for leaks. That being said, the problem is that the evap vent valve has a filter inside of it, it can get clogged and not allow air to vent out of the fuel tank. This makes the fuel tank impossible to fill, the air has to go somewhere, when you are filling the tank and the vent is clogged, the air shoots out of the filler neck, which causes the fuel fillter pump to stop as if the fuel tank was full.
To repair this issue, you need to replace the evap vent valve. It's located unnder the truck, just behind the fuel tank. The evap cansiter will have a large hose going to this valve and it has 1 eletrcail plug. Below is a diagram of the valve. Is kind or round, and has the hoses connected to it.

Object Number:(NNN) NNN-NNNN Size: SH
Customer: replied 7 years ago.

I have replaced the valve and it worked for a couple of days then the problem returned. What else could be wrong?

Try unpluging the large hose going to the valve and see if this helps. It maybe the canister that is clogged. If unpluging the hose to the valve does not help, remove the large hose at the canister, the hose from the tank needs to be removed. If this stops the issuem then the canister needs to be replaced.

Object Number:(NNN) NNN-NNNN Size: SH

Evaporative Emissions Hose Routing Diagram

EVAP System Overview

Object Number: 678941  Size: LF
(1)EVAP Canister Purge Solenoid Valve
(2)EVAP Canister
(3)Fuel Fill Neck/Fill Cap
(4)Rollover Valve/Fuel Tank Pressure (FTP) Sensor
(5)Fuel Tank
(6)EVAP Canister Vent Solenoid Valve
(7)Vent Hose/Pipe
(8)EVAP Vapor Pipe
(9)EVAP Purge Pipe
(10)EVAP Service Port

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