My slow refueling adventure

This is for a 2001 986 base, but identical to the 996 regarding this problem...I'm having the all-too-common problem of the tank not filling to the top. Constant clicking off of the pump nozzle. Filling the tank with the fuel handle at every angle of 360 degrees didn't work. Pushing the little tab that's normally depressed by the cap didn't work (although the tab is looking kinda worn). This has been going on for a few years, and I'd talked myself into thinking this is just a Porsche thing, but now I want it fixed. It did work, so there's something wrong. No CEL/MIL. No difficulty starting after filling. After a ton of research, it finally sunk into my pea brain that there are two systems: the main Evaporative Emission Control System (EVAP) that captures stray fuel vapors while operating and sitting, and the intermingled Onboard Refueling Vapor Recovery system (ORVR). It's the ORVR that vents the tank during fueling. Pushing the fueling nozzle into the filler hole moves a flap that activates a reed switch on the filler pipe. This switches operation from EVAP to ORVR, activating two valves: - the ORVR valve on top of the fuel tank - the "fresh air" valve located in the front right wheel arch With those two valves open the tank can vent to atmosphere during fueling, through the carbon canister. So why is mine not working? Some people have a problem with Fuse E6, which powers the ORVR system (grounds out from a telephone connector in the center console). Mine is fine. So next is the two valves. I pulled off the wheel liner to get to the valve in the wheel arch. I can hear and feel it activating. Then I pulled out the battery and the lid under it, getting to the fuel tank. The ORVR valve there I could also feel activating. Assuming the valves are actually doing something, that leaves the carbon canister and the interconnecting hoses/pipes. The atmospheric line from the fuel cap area seems like a potential culprit and it's subject to collecting debris. My question: how is the line disconnected from the valve plenum without damaging it? See pic Assuming the lines aren't plugged, and the carbon canister is plugged, wouldn't this set off a CEL/MIL? It is part of the EVAP system as well. Then there are a couple of potential mechanical issues not related to ORVR air flow. The spitback valve at the end of the filler tube could be sticking or blocked. But woudn't the tank be difficult to fill in its entirety, rather than just near the top? Then there is the issue with the flexible fuel hoses inside tank obstructing the spitback valve. Porsche issued a TSB: Fuel Tank Hose Modification 5/99 2015 or 03/99 2015 (different numbers from different forums) - tie fuel tank hoses out of the way of filler pipe flap. I couldn't find the TSB. Is it applicable to cars past 1999? Does it make sense that like in my case it started about 15 years after the car hit the road? Can this be determined by putting a scope down the filler pipe or would the spitback valve get in the way? I did try this but got chicken and stopped when the scope got to a section of the pipe that looked corrugated. So my questions, for those of you kind enough to help: 1. How is the pipeline disconnected from the valve plenum without damaging it? 2. Wouldn't a plugged carbon canister set off a CEL/MIL? 3. Does anyone have the TSB? What years is it applicable to? Can this happen many years after the car is sold? 4. Have I missed anything as far as potential failure mechanisms or is there any other advice? Thanks!

Your vent lines might be plugged. Remove lines from vent valve in wheel well and try to blow air back through lines using a turkey blaster. that�s wheel arch and turkey baster

mine was a blown radio fuse (or something similar, totally unrelated to fuel system)

Have you noticed a difference between stations or even pumps at one station? I've found that at some I can't lock it on - it will click off almost immediately. At those, I have to simply hold the trigger part way, effectively just reducing the flow. There is one (petro-canada) station near me where it works well, I can just pump gas and fill it up as with any other vehicle. HOWEVER, using the reduced flow technique or the PC pump, I am more likely to overfill it. That's likely my own error, because I've convinced myself that is shuts off too early after all the times I "filled up" to 3/4, and I keep trying to top up past full. I'm just not sure if I have a problem, given that it works fine at some pumps and not others. Somebody on here will know for sure, but I'm reasonably confident that there are specific requirements for a maximum flow, and for the design of the nozzle and auto-shutoff, so the difference has to be related to the flow rate for my car, broken or not.

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That's what I'd like to do but not sure how to disconnect the tube without damaging it. Any advice? thx

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Yeah mine works. Ruled that out first...

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In BC Chevron is the only station that offers 94 octane without ethanol. And their pumps all do it. Yes I've overfilled too. Messy, wasteful, annoying and can apparently destroy your carbon canister.

I had the filling issue as well with my 996 however I got out of it easy I guess just buying the vent valve fixed it! Previous to that it was embarrassing when the fuel would click off and I would try to put more in, then my car would decide to puke out a quart of it all over the ground....

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When you say "vent valve" I assume you're talking about the one wrapped around the top of the filler neck. (On the Porsche parts list it's calIed a "bleeder valve".) I don't get how this impacts venting of the fuel tank while refueling. The diagram I found shows that valve as part of the EVAP system not the ORVR. Did you happen to replace the reed switch mounted on the bleeder valve while doing that job? Or find that the reed switch was out of place and put it back? That switch is part of the ORVR.

Usually, replacing the bleeder valve will solve the problem. Is a quite easy job once you get to remove the fender liner.

Can't offer any help but I'm impressed by your problem description and analysis. Clear and thorough, very nice! Crossing my fingers for you that the replies help you solve it.

Hello guys I hope some one will be able to help me. I have 911 - 996 model. For the last few years i also have problem with refueling and i also have engine light turned on. So few days ago i said i will try to solve this. I think i read EVERY forum about this problem now So... i checked everythink what i could find, charchoal canister vent valve, fuse E6 etc. And Everythink is fine. But i dont get that clicking sound when i try to push filler cap inside. Today i found out, if i put magnet by the reed switch (that short stick which is inside vent valve), then i hear clicking sound inside. So looks like everythink is working at my car, i just can not find out what is normaly trigering that switch? Because magnet trigers it, but if i just lift up that blockage inside the filler tube nothing happens. can any one help me ? Thank you

I actually can't help you, but I have the same symptoms you have... If I put a magnet by the reed switch it activates the valve with a loud and clear click, but simply opening the fuel backflow door doesn't do it. I am wondering if there is/was a magnet on the back of the door, possibly in the indent, that fell off? Absent a magnet, what else would activate it, or maybe it is a magnet and has worn out or impinged somehow. It seems no one in these forums actually has that information... I just ordered a new reed switch to find out. I'll let you know, and please post if you find a solution. Kinda tired of Porsche issues...

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Hey, well i gave up. I also wanted to order new reed switch but then i thougt why, if it works with magnet so it is probably ok... Like u said i think that there should be magnet behind the doors, so when you push hose for gas inside andnit pushes it up, it should activate it. probably only solution is to change filler hose. Only other solution is to cut wires from reed switch and make small push button switch somewhere so you can activate valve manually when you put fill the gas inside, and when you finish you turn off that switch. Does maybe anyone knows wiring of reed switch? when it is activated it probably connects 2 wires which goes to that switch right?

Soooo...... I received the new reed switch this morning, replaced it and... total surprise, it works. I don't have an explanation, but what I think is that there is a magnet in the small flap in the fuel filler tube, maybe.... The old switch works when you place a magnet against it but otherwise isn't working against the smaller magnet in the filler due to age... The other thought is the reed switch itself is the magnet and simply worn out, so when in proximity of a strong magnet is activates... $39 at Pelican Parts... and btw, I emailed Pelican Parts as to the function of the reed switch and crickets so far. Cheers

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hey i cant believe it. Maybe you solved really big problem for us all. I will order new reed switch right now and hope for the best. i will let you know if it also saves my problem. thanks again for your help!!

I just ran down to the service station and fueled up. No problems at all, fuel went in without having to hold the pump handle at 90 or keep the vapor seal on the pump handle open.... So, it was a bad reed valve even though a magnet would actuate it. I think this may be the answer to a few peoples issue.

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I think so too. That took a while to figure out. I am so surprised that there wasn't more info on how that switch worked. Even Pelican Parts didn't get back to me... anyway, even if it is not the problem it is easy and cheap to rule out. Good luck to you.

This post is offered for the intended benefit of all who may be unaware that the 1999 C2 996 has a mechanically activated evaporative system vent. I learned this by taking a long laborious path in attempting to correct a P0453 code (excessive fuel tank pressure). I removed and tested all evaporative system sensors and valves - fuel tank pressure sensor, shut off valve, purge valve, and vent valve on side of filler neck. In addition I disconnected the ECU and tested integrity of all pertinent wiring circuits. Finally I realized the excess tank pressure was occurring due to the wrong fuel cap design that failed to open the vent valve mechanically as required to vent the tank into the charcoal canister. The vent valve on side of filler neck on the 1999 996 shuts off the vent line from the tank to the charcoal canister when fuel cap is removed. When the correct fuel cap is screwed on it activates and opens the vent valve so as vapor pressure is released from the fuel tank into the charcoal canister. I had bought a new replacement fuel cap that was represented as a direct OEM equivalent replacement but it was not as the flange on the cap was insufficient in depth to activate the mechanical lever on the vent valve. Hence, the takeaway be certain you are acquiring the correct fuel cap design when replacing your fuel cap, The photo below shows the vent valve removed from my 99 996, the red arrow points to the sliding lever on the valve that the fuel cap activates when the correct cap is in place on the tank filler neck. p design is in place on the car..

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Would you happen to have the part number for the reed switch you ordered? Thank you

The attached photo reveals the positioning of the sensor on the vent valve housing and is courtesy of toddmac12 posted Feb 10, 2018 ( https://www.renntech.org/topic/51885-spitting-gas-ugh/ ) The wire connector for the sensor is reported to be in the wire harness near the vent valve and filler neck. Link to sensor source - https://www.pelicanparts.com/More_In...gaAtYEEALw_wcB

Cold anyone who has installed a Porsche Fuel Tank Bleeder Valve Sensor - Porsche 99661322401 (photo below) (also referred to in the above posts as a "reed switch") on a 996 comment on the wire harness plug connector that the valve sensor plugs into? On my 1999 996 C2 the original bleeder valve sensor was missing on the car when acquired used. The factory wire harness has a connector that is identical to the connector plug on the new sensor. Could someone please advise what type of connection plug prevailed in your 996 application. Is it possible that an adapter device is needed to connect the sensor to the factory wire circuit? A new bleeder valve sensor - how to connect it to the factory wiring harness? This is the plug connector on the factory wiring harness of my 1999 996 C2 - it is identical to the connector on the new bleeder valve sensor - how is the install wiring connection accomplished?

I'm having a similar issue with my early 1999 996. I'm trying to locate where the reed switch plugs into on the actual car/harness. My reed valve is nowhere to be found when you compare it to the other photos online and in this thread, and it was not in the old vent valve attached to the filler tube. Could the early 1999 996s have had a slightly different design, which is why the original Pelican article didn't mention it? It makes enough sense to me. There is a gray plug that looks the same as the new reed switches I'm seeing online, shown in picture 3. I believe the reed switch for my car is somehow in the taped bundle, shown best in pictures 2 and 3. The bundle of wires where I suspect the reed switch is, please note that multiple connections combine in this bundle. Also, this is really close to where the reed switch is supposed to mount on the far side of the vent valve on the filler tube. Bundle shown again, note the gray connector matches the reed switches that are sold on Pelican Parts and FCP. That's just my hunch of what's going on with my early build and lack of a visible reed switch. I have a new reed switch showing up that I'm going to install where that gray connector is. I've had filling issues lately, so I decided to install a new vent valve, which is where this reed switch issue originated.

I�m the original poster and should close the loop. My problem ended up being a plugged carbon canister, presumably from overfilling numerous times. My indie first thought it was the valve on the fuel filler neck. After a lot of diagnostic work they took out the canister for me to try filling the gas tank. Which worked. Caveat on no canister: stray fuel vapours won�t be captured, so be careful to avoid a fire.

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So they didn�t replace the canister? Why not?

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Funny, this seems to be a Canadian thing! I live in Halifax. I have to avoid the two gas stations near me but the one a few miles away works fine on my 996. Also, 91 Octane is the highest grade I can get here. For that reason alone, I�m for the 51st thing�

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I wasn�t clear enough. They replaced it once I confirmed refueling worked and they were able to get the part.

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Did you ever figure this out? I also have a 1999 C2, and it doesn't have this reed/contact sensor, or the connector anywhere. I'm guessing the cable throttle cars are slightly different, but I'd hate to put everything back together without knowing for sure. Thanks.

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I didn't find a reed switch on my 99. My issues ended up being rat and mice related.

After more research I think I've found some important information that can help others in the future. I google searched 996 "ORVR", and happen to come across the options list we've all seen before. One of the options listed was code 664 "ORVR Onboard Refueling Vapor Recovery". After checking my own option list (1999 C2 Canada) it did not have 664 option, which would explain the missing reed switch. I don't know if it's only cable throttle cars or only Canadian models, but if you can't find a reed switch check your option list. In my case the difficult refueling was caused by the filler vent valve. The plunger that closes the valve when you remove the fuel cap was sticking. Refueled no problem this weekend, and code P0446 hasn't come back yet after 30km.

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For what it�s worth, not all codes listed on the option list in PET will appear on the build decal. Mine is a US car but doesn�t show M553 (Version for USA, Canada), M563 (Side airbag) despite those being true. From what I can see, those cases it�s a differentiator to explain the different part numbers (and applications) for the same item.

Good point. My car no longer has a decal, so I hadn't considered that. I had ordered a full build sheet a fews years ago. That's what I compared to.

Hi Guys, 2003 996 4S I have been having the usual refuelling problems. I removed the fuel tank bleeder valve, found the slot where the reed switch goes and no reed switch. Definitely no reed switch. I have an electrical connector that looks exactly the same as the connector on the reed switch replacements plugged in, but no reed switch the cables from that connector follow the tank filler line. This 996 does not have a cable throttle. It is a right hand drive purchased and picked up directly from the factory in Stuttgart. I looked up the part number for the fuel filler which I could see and got this result.Porsche part number 996-201-043-03 is a Genuine OEM Gas/Fuel Tank Filler Neck designed for various 1999�2005 Porsche 911 (996) and certain Boxster models. It is specifically used in all-wheel-drive (AWD) models without ORVR (Onboard Refueling Vapor Recovery) and 2WD models equipped with the GT3 I think I'll just install the new fuel tank bleeder valve without the reed switch and take it from there.