Resendiz

The middle, bigger hose is just hanging, isn't connected to anything. What is it for?





This little guy has nothing as well. What's it meant for? And should I be worried that nothing is there?

burnhedge

Vapor canister. I believe the hose is the vent so it shouldn't be hooked up. I think the purge is supposed to go back to the motor somewhere maybe the throttle body. I'd have to look on one of my trucks to tell you for sure.

Resendiz

Please do. I'd like to plug it to something

tech2

What year truck?
that is the evaporative emission charcoal canister. the purge line should connect back into the tbi. the vent line is a fresh air inlet to the canister and may connect to a filter to keep dirt out....some may have an internal filter in the canister. the remaining line should connect back to the tank.

Resendiz

My brother has an 89 Silverado 5.7.

I took pictures today and got to see where these lines go. For anyone reading this in the future, I took some pictures...







Purge has hose going to tbi<br/>Air cleaner has cap that protects it from dust it seems. Not fully sealed.

Resendiz

Here's the bizzare part... I just checked my truck to try and match. And it seems that the prior owner took the hose from the tbi directly to a bolt, blocking it from getting any air. How does this effect the truck? This can't be good.







My truck. I removed the hose to take a clear picture

Resendiz

What is the damage being done by connecting the purge hose to a bold, blocking air to it?? This looks like trouble, but I don't understand this engine enough to know why this is bad.

tech2

damage...none as long as the tbi port is capped.


the evap system will be not functional. the damage will be to the environment as hydrocarbons will be released to the atmosphere when the canister gets to its saturation point.

Richardx2

Connecting the vacuum line to a bolt just prevents a vacuum leak at the TBI.

The purge canister collects gas vapors from the engine and uses it to store the vapors until the ECM allows the vapors to be routed back into the TBI unit.

Here is a link that explains a bit more, I know the link is not for a Chevrolet truck but the concept is the same:

| Repair Guides | Electronic Engine Control Systems | Throttle Body Fuel Injection (tbi) | AutoZone.com

tech2

there is no ecm control of the evap system on these old cars. for that you would need a purge solenoid.
once the throttle is moved off idle, the tbi port is opened to manifold vacuum and starts drawing vapour from the canister.