When I fill up gas at the pump, the pump continually cuts off as if the tank is full. I spend about 10 minutes at the gas station filling up the tank, and I can never tell if the tank is full or if the hose is just cutting off. The car mechanic told me the replacement vent line cost $200 to $300 to replace (with labor). Is there any cheaper solution?
You don’t mention the model year of this Mazda Tribute. I will assume it is 2000 or newer. It appears that your mechanic has determined that the tank is not venting the trapped vapor so the pump nozzle shuts off when the fuel climbs the fill pipe.
These gas tanks are now vented through the vapor recovery canister during filling. The usual path is the vent line from the tank to the canister, through the canister activated charcoal, through the canister open valve, and hence to the atmosphere or high on the fill pipe. If there is a plug in any of these hoses or pipes; the canister open valve is not working; or the canister has gotten filled with liquid fuel, there will be a venting problem.
There are a couple of other possibilities. The first is the antirollover spill valve has gotten stick closed. This is a one way valve that is at the tank end of the fill pipe that keeps fuel from going from the tank up the filler pipe. If you suspect this is stuck you can thread a fiber glass rod down the pipe to push it open. This valve is built into the tank and is not replaceable.
There is another valve that blocks off the vent vapor flow when the tank is appropriately full to allow the incoming fuel to back up the fill pipe to shut off the pump nozzle. If this is stuck closed, the tank will not vent. A mechanic might be able to back probe the valve to get it to open. This valve is part of the tank and usually not replaceable.
Hope this helps.