EVAP purge valve

[///RAGMC]

Has anyone ever had to replace the evap purge valve? Had to fill my truck up yesterday and there was alot more pressure than usual when i removed the gas cap.

 

[twomanymontes]

The EVAP Purge valve is the one that adds Vacuum to the EVAP system. If that was stuck open, then you would A) Be running richer than normal and B) having vacuum when you released the gas cap. The Canister Vent Valve is what I believe you mean. It will vent the pressure in the tank. Those go bad all the time.

Not sure where yours is mounted, But I believe it hanging off to the side of the canister.

 

[///RAGMC]

Its mounted to the right of the tbi looks like it stopped working i need to give it a closer look to see whats up with it.

 

[twomanymontes]

That is the purge solenoid. They are easy to swap, one bolt, connector and the quick connect line. That just controls the vacuum to the EVAP system. It doesn't run all the time. Best thing to do is use a scan tool that has bi directional controls and activate it to see if it is working.

 

[///RAGMC]

Had the truck out yesterday and come to find out there is no valve. The vent line comes from the tank to the canister then to the TBI.

 

[twomanymontes]

What year is your truck?

 

[///RAGMC]

91 GMC

 

[twomanymontes]

Ok, I thought you had a later model. With the Denali front end it looks like a newer truck. That's where I got confused with your posting. Sorry.

The Vortec motor has the purge solenoid mounted to the manifold on the passenger side next to the throttle body. The regular TBI has a solenoid mounted in front of the Throttle body and a line running to the canister on the left front corner of the radiator support. You said you don't have a solenoid, That doesn't make much sense. With no solenoid you would have consistent vacuum to the tank through the canister. It would always be stuck in a vacuum. and be running rich all the time.

 

[///RAGMC]

It was also 108 here that day too. I messed with it today and blew all the lines and the canister gonna keep an eye on it to see if i does it again. Thanks for the help.

 

[twomanymontes]

Help? I think I just confused the two of us. Hopefully it was something as simple as plugged lines.