I have this problem too. It's a huge hazard to be spilling this fuel all over at the station everytime I fill up!

I've heard three suggestions here:
1. Check the fuse - what fuse are we talking about here?
2. The reed switch was pulled out of the lock. They partially removed the filler neck and reinstalled the reed switch back into the lock. - where is the reed switch and what is it supposed to do?
3. Blow out the breather tube with compressed air - where is this tube?

Thanks
Jeff

 

can you guys hear the valve or whatever it is pop open when you put the filler neck in the gas tank? it sounds like a relay switch. I have noticed that if I fill at the 9 o'clock position (or just lift up on the gas handle) I can hear the relay or whatever it is work. When that relay is activated, the tank will fill up normally. When that relay isn't activated I generally only get 9 gallons in there and the gauge reads 3/4/ full..

I've never experienced any sizeable amount of gas spill out of the tank while filling up.

 

There's an electronic vent tube valve located just past the fuel door area. To access it you need to lift car and remove passenger front wheel/fender well shroud and you'll see it up attached to the aluminum tube. If that doesn't function, the tank cannot vent while filling. Takes awhile to fill it slowly, but can be filled.

However if I remember correctly, there is also a built in rollover valve in the filler neck down near where it attaches to the tank that can stick closed. If it does, the tank is almost impossible to fill by means of the filler neck and fuel spills out as fast as you can put it in. This is currently happening to a car here.

Check the solenoid first, it's an easy fix if that's the case. Repairing or remedying the fuel neck is more in depth. That requires dropping other parts off the car to access. If you're a DIY'er, do not attempt the latter fix with anything more than a couple gallons of fuel in the tank. Syphon it out of the fuel pump access panel on the top of the tank prior to that work.

 

The problem is not the typical problem of only getting 75% full. It's that we're routinely getting 100+% full and spilling gas all over the ground.

Winds here in Colorado are gusting to 50+mph, I couldn't hear the gurgling when it's full, let alone a relay clicking.

 

The tank fills at normal speed and fills completely - even more than completely. Something with the car negates the usual function of the autostop feature at the gas station. Happens at all stations, and doesn't happen at the same station with my other cars. Even other P-Cars.

 

Odd. Pump shutoff is typically controlled by a venturi tube in the fuel nozzle. Wonder if the vent is stuck open

 

Vent stuck open - hmmm.. That makes sense. I need to check it.

 

Making some headway here. In the garage, if I push my finger on the fuel filler valve door just behind the gas cap - I can indeed hear the clicking when the door is open/closed.

How do I test the vent? It all looks so new in here. Car has only 27k miles, but is 10 years old. So it must have aged some rubber component?

So we're looking at the part 996.201.143.01 Fuel vent valve #12. I'm noticing there is a similar vent on top of the gas tank, 996.605.203.01 Fuel Tank Vent Valve #23
http://dcauto.gotdns.com/illustration/index/2160710

 

Ok I have the 996.201.143.01 valve in my hand. I'm not exactly sure what it's supposed to do. How do I test it?

Also I see the reed switch, it's just a loose reed switch that fits into into a groove in the bracket for the above valve. There must be a magnet inside the fuel filler flapper that activates it.

 

Does the reed switch (and relay) control the vent valve on top of the gas tank? I suppose it does, and if that system isn't working (stuck closed), then yes you would have a very hard time filling the tank. But if it was stuck open, I don't think this would interfere with filling at all, since it's supposed to be open whenever you've got the refueling nozzle inserted into the car.

Does the fuel cap press down on the lever that opens the vent valve?

Is the vent valve supposed to be completely closed to air going in either direction when the cap is off? Mine is not, low pressures on the air inputs in either direction seem to make it open a bit. I don't have the "howling" symptom that's usual with failure of this valve though.

 

Correct, it's just a proximity switch. I forget what fuse it goes through, but that's what activates the vent valve down on the tank. If you're not having an issue filling the tank, then it's certainly opening(or at the least stuck open). the prox switch can be tested with an ohm meter and just swinging the reed by a magnet(use a refrigerator magnet or something similar).

The red top valve IIRC is associated with the EVAP system and I though just redirected the tank vapors to the canister when the tank is being filled. The cap does push down on that thin lever in the plastic housing, which itself pushes back on the valve rod to the main valve(red plastic)

The filler hoses on fuel pumps use a venturi to stop the flow of fuel. When it gets a pressure differential of about 1psi it will trip the valve in the handle of the pump and stops the flow of fuel into the car. If for some reason the fuel tank is continuing to vent even with fuel filling up the filler neck completely, then the handle will not trip and you'll have gas pouring out the inlet area. the tank should stop venting as soon as the vent line in the tank sees fuel level(full tank) The pump handles will shut down when the end goes under fuel completely if in the event fuel rises up the filler neck, but by that point it's too late and the remainder flow of fuel going in usually spills out and down the side of the paint.

I had this problem on an Ultima GTR where both tanks were linked together and it always made a f-ing mess until I rerouted some tubing and related hoses.




also will add for those experiencing the opposite issue of this and cannot get ANY fuel into the tank your flapper valve is likely stuck closed. Just did the quick fix for this on a car here. Go to your local welding supply shop and buy a standard length of 1/8" aluminum Tig rod. Bend a VERY slight arc to it, and put a 90 degree bend in it 32" from one end to help twist it around if necessary as you're feeding it down the curves of the filler neck. Valve is located 29" down from the sealing lip of the filler neck.

 

What do you mean by "fill up at the 9 o'clock position"?

 

Normally when you put the filler nozzle in gravity is pulling it straight down (6 o'clock position on the hour pointer of a watch a watch). If you lift the handle up while inside the fuel filler, or rotate the the nozzle 90 degrees, you are now holding the nozzle sideways or facing teh 9 o'clock position. The point is that there is an electronic "flap" inside the gas receptacle that is supposed to activate when you insert the gas pump nozzle in. You want to engage that so that the flap opens inside the gas tank and allows you to fill it up all the way. Otherwise you get 3/4 tank most of the time.

You can hear the flap clicking open when the nozzle is being pulled up (literally pull up on the gas nozzle while inserted in the gas tank) instead of letting it rest down by gravity. or try the 9 o'clock position.

It took me 5 years top figure out how to permanently solve the car won't take more than 3/4 tank issue. But now, the car fills up all the way every time.

I think the OP has a different issue. Probably a clogged or crimped vent line...

 

I'm having the same problem. I fill up and the pump clicks telling me its "full" but then i drive away and i notice my gauge only reads 3/4 full. So the next time i fill up and the pump clicks but decide to pump a bit more to get it full then next to you know i'm overflowing. So is it a relay switch or valve?

 

THIS! first time it has ever occurred was yesterday! Thanks for figuring that all out, will make my life much easier.