Charcoal Canister 90 Suburban

richardberg · Feb 13, 2023

My 1990 Suburban chugs a little bit at idle when warm. Also takes a little while for it to start. When it chugs at idle i can see the gas gauge move a little bit with every chug. Could this be because of a plugged gas tank vent? How do

I test the charcoal canister and the hoses? I have two hoses. The on leading to the gas tank holds vacuum. Should it hold vacuum or does it mean the line is plugged?

Ricko1966 · Feb 14, 2023

Check your charcoal canister purge valve. I cannot answer as to whether or not it should hold vacuum or if it's plugged. It should hold vacuum,but if it is plugged it will hold vacuum,so not an accurate test.

75gmck25 · Feb 14, 2023

On the older trucks the vent line to the tank is connected to an open port on the sending unit, and you can’t get it to hold vacuum if you pull vacuum from the charcoal canister end. However, you need to get an emissions diagram to determine whether yours might have a check valve in the line.

gmbellew · Feb 14, 2023

you could disconnect the line from the gas tank at the cannister and see if that helps the idle. the vac port on the TBI for the cannister doesn't pull vacuum at idle, so it shouldn't create a vac leak at idle.

Ricko1966 · Feb 14, 2023

Take that line off,take off the gas cap ,blow through the line then try to pull vacuum on it that will let you know if that line is plugged and if there is a check valve. Try and drive it with no cap see if your problem is gone.

Rusty Nail · May 12, 2023

*crickets*

fast 99 · May 12, 2023

Rusty Nail said:
*crickets*

Yeah, have noticed some aren't the least bit appreciative and don't reply after asking a question. Today's society, I guess.

Charcoal Canister 90 Suburban

richardberg

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