Can't fill up gas tank
05-10-2014, 03:43 PM
#11
Some rollover/evaporative emission valves can get stuck or clogged.
I'm not sure if you have one like the one I have (see picture below) that is equipped to the front tank.
Basically how the system works is the valve you see on top of the tank is the evaporative emission valve mounted on the top of the fuel tank is used to control the flow of fuel vapor entering the fuel tank vapor delivery line which conducts vapor forward to the evaporative emissions canister in normal circumstances. If, due to extreme conditions, excessive pressure is generated inside the tank, the purge port opens up, allowing fuel vapor to escape to the atmosphere, and stabilizes pressure inside the fuel tank. The evaporative emission valve has a head valve which prevents the fuel tank from overfilling during refueling operation. The evaporative emission valve also has a spring supported float assembly, which prevents liquid fuel from entering the vapor delivery line during severe handling, steep grades or in the event of vehicle rollover. Now when the engine is off the pressure from tank will open the valve and let vapors go into the vapor lines to the carbon canister in the front. Then when you start the vehicle the canister purge valve will open and draw the vapors from the canister back into the engine to be re burned. Now the canister is sealed and should not leak but it does not really hold pressure. The valve in the tank should close when the pressure equalizes in the tank. and the carbon in the canister absorbs the vapors and holds them until the engine is started. Also check the canister purge solenoid make sure it click good if you supply power on the red wire just to make sure it isn't stuck and you can unhook the hose and pull a vacuum on and make sure it is not leaking.
Another type of vapor valve is for the rear tank.
Canister
Vapor Line Routing Diagram in a 95 (Same as 90-96); from Vapor Cannister to Fuel Tank. The system begins in the fuel tank where one or more valves are used to vent vapor pressure, but also to exclude liquid from the vapor system due to overfilling, slosh, or rollover. There may also be a pressure sensor to monitor the system's operation & effectiveness, and/or a vent valve (CANV solenoid, or built into the cap) to allow fresh air into the fuel tank or vapor system. As vapor exits the tank, it flows thru a tube to a canister containing carbon (activated charcoal), which absorbs the fuel vapor, but allows air to pass. Depending on the size of the fuel tank, there may be several canisters, or a larger canister. Older canisters are vented, but they're known to collect water, so most modern canisters are sealed. Another tube leads from the canister toward the engine's intake, but it may contain a regulator valve (CANP solenoid, or VMV). Being virtually a zero-maintenance system, most faults are simple valve failures, hose leaks, or mechanical damage (collision, road debris, etc.).
I'm not sure if you have one like the one I have (see picture below) that is equipped to the front tank.
Basically how the system works is the valve you see on top of the tank is the evaporative emission valve mounted on the top of the fuel tank is used to control the flow of fuel vapor entering the fuel tank vapor delivery line which conducts vapor forward to the evaporative emissions canister in normal circumstances. If, due to extreme conditions, excessive pressure is generated inside the tank, the purge port opens up, allowing fuel vapor to escape to the atmosphere, and stabilizes pressure inside the fuel tank. The evaporative emission valve has a head valve which prevents the fuel tank from overfilling during refueling operation. The evaporative emission valve also has a spring supported float assembly, which prevents liquid fuel from entering the vapor delivery line during severe handling, steep grades or in the event of vehicle rollover. Now when the engine is off the pressure from tank will open the valve and let vapors go into the vapor lines to the carbon canister in the front. Then when you start the vehicle the canister purge valve will open and draw the vapors from the canister back into the engine to be re burned. Now the canister is sealed and should not leak but it does not really hold pressure. The valve in the tank should close when the pressure equalizes in the tank. and the carbon in the canister absorbs the vapors and holds them until the engine is started. Also check the canister purge solenoid make sure it click good if you supply power on the red wire just to make sure it isn't stuck and you can unhook the hose and pull a vacuum on and make sure it is not leaking.
Another type of vapor valve is for the rear tank.
Canister
Vapor Line Routing Diagram in a 95 (Same as 90-96); from Vapor Cannister to Fuel Tank. The system begins in the fuel tank where one or more valves are used to vent vapor pressure, but also to exclude liquid from the vapor system due to overfilling, slosh, or rollover. There may also be a pressure sensor to monitor the system's operation & effectiveness, and/or a vent valve (CANV solenoid, or built into the cap) to allow fresh air into the fuel tank or vapor system. As vapor exits the tank, it flows thru a tube to a canister containing carbon (activated charcoal), which absorbs the fuel vapor, but allows air to pass. Depending on the size of the fuel tank, there may be several canisters, or a larger canister. Older canisters are vented, but they're known to collect water, so most modern canisters are sealed. Another tube leads from the canister toward the engine's intake, but it may contain a regulator valve (CANP solenoid, or VMV). Being virtually a zero-maintenance system, most faults are simple valve failures, hose leaks, or mechanical damage (collision, road debris, etc.).
05-10-2014, 06:05 PM
#12
Some models have what appear to be one tube when in fact there are two, one inside the other. Vent tube inside fill tube.
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05-10-2014, 06:39 PM
#14
Senior Member
I think on that one ^^^^^ the inner is the fill and the outer is the vent. But either way, if it can't vent properly, it won't fill properly.
05-11-2014, 07:56 AM
#16
Senior Member
What is the "proper section" for this type of thing?
And if this is the wrong section, what is "this section" for?
05-11-2014, 09:32 AM
#17
Suggestion implies or indicates a certain fact or situation.
I volunteer to help others and share some ideas. I know that I am not an expert, but I am a quick learner, self taught mechanic that I can solve or troubleshooting of anything in my path. As always, I love to be given problems that require creative ideas. I am self confident and with integrity that requires resolving without giving up to that seemingly inexhaustible...
I volunteer to help others and share some ideas. I know that I am not an expert, but I am a quick learner, self taught mechanic that I can solve or troubleshooting of anything in my path. As always, I love to be given problems that require creative ideas. I am self confident and with integrity that requires resolving without giving up to that seemingly inexhaustible...
05-11-2014, 12:34 PM
#19
It's not always a venting problem - I recently fixed a car with same sx and figured it was venting, but in the end the inner part of the lower fill tube (which was rubber with some sort of plasticized lining) had partially separated and was basically warped and closing off the interior of the tube, so only very slowly would fuel go past that obstruction.
If you can't clear the vent tube, take the tube off and check for any obstructions.
If you can't clear the vent tube, take the tube off and check for any obstructions.