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Charcol cansister

how would a person know if they had a faulty charcol fuel cansister

You may get a CEL (Check Engine Light) or you may not be able to fill the tank without the automatic shut off of the pump going off often.

Both of the above can be caused by other problems.

Do you think you have a problem, and if so why? (What make, model, year and miles for your car)

Where did this idea come from that the charcoal canister has anything to do with filling the gas tank on a 1998 Ranger? There’s no connection, until some vehicles, starting in 1998, had OPVR (Onboard Refueling Vapor Recovery) installed. Does the 1998 Ford Ranger have OPVR?

Here is EPA (Enviornmental Protection Agency) ruling on OPVR:

The gas tank vents straight to the charcoal canister. That is the main purpose of the canister. To collect gas fumes from the large gasoline reservoir in the back until the engine is ready to purge those fumes through the engine to be burned.

Overfilling the tank can lead to raw gas, not gas fumes, getting sucked into the canister when the purge valve is open. This will saturate the charcoal, and lead to gas fumes escaping out of the bottom vent. When this happens, you’ll get a gassy smell under the hood,and possibly in the cabin through the vent at the bottom of the windshield. This can also lead to a pressure differential that can trigger the gas pump into thinking the tank is full when it is not.

I own a 98 ranger with 150,000 miles on and it is good .I just read a articale topping off the fuel tank a possibly distroying the cansister.

Wally, just replace the canisiter if you smell fuel when the car is at operating temperature and there is no other obvious sign of a fuel leak.
The canister is a temporary storage place for vapors that are created and not used. Then it flows back into the tank. Gases and vapors that naturally occur inside the tank are vented out through the gas cap especially when you remove the cap. notice that it says “Remove cap slowly” on the fuel cap? If the canister was a vent for the tank gases would combust in the engine compartment because of the heat and the unlikely stray spark.
Please be careful about who you accept hints from. Unfortunetley this forum gives some of the mentally ill in our society a place to abuse others by exagerating their knowledge or to sell dishonest dealerships. Never, ever trust a dealership.

Did you ever stop to ask yourself why the manufacturers put those stickers on the cars warning about topping off the tank?

You can only know for certain if you have a defective charcoal fuel canister if you check it by following the instructions in the repair manual. There isn’t some simple, surefire, answer. Sorry, it’s too complex to be simple.

Hi Norm!

Cars did JUST FINE without charcoal canisters for 60 or 70 years. So will your Ranger. The fill caps were vented. We all survived. OBVP is something new. The older canister systems were not used during refueling. The tank vented out the filler neck when the cap was removed… They COULD be damaged by over-filling, which would force liquid gasoline into the vent line after the cap was replaced and the tank built up pressure…

This is probably a California car. They have used canisters for far longer than anyone else, and constant topping off the tank will flood a canister with fuel, making it very hard to fill the tank properly. I have had pretty good luck by removing the canister and putting it out in the direct sun, with every tube and hose disconnected, and let it “dry out” inside. Obviously this is somewhat dangerous, because of flammable fumes and so forth, so be careful and certainly don’t try to dry it out indoors.

It always struck me as strange why charcoal canisters were replaced when they had excess gasoline in them. The charcoal canister’s job is to handle gasoline (ok, gasoline fumes). What’s so hard about removing any excess by gravity, by evaporation, by letting an engine vacuum it out, by blowing it out with low pressure air (but, not a bar-b-que)?

I believe that when the charcoal has been saturated with liquid gasoline, it no longer has the ability to neutralize fumes. After many years of dealing with gas fumes, this can happen too, but the process is accelerated by liquid gasoline. At least this is the explanation that I have been given.

I believe the process to clean it out, would be far more than the cost of a new one.

Gasoline is a blend of compounds with different boiling points. They range from very light, like ether, which evaporates easily at a low temperature, to heavier oil-like fractions that boil above 100F. Normally the canister gets only the lightest fractions because they tend to evaporate off the liquid in the tank first. These readily re-evaporate from the charcoal when a vacuum is pulled while the engine runs. When liquid gas gets in the cannister however the heavy fractions get in there and they tend to stay.