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Griffter
Monza


Joined: 22 May 2016
Posts: 216



PostPosted: Sat Sep 01, 2018 8:49 am    Post subject: Reply with quote

Is the system passive, or are any of the valves operated by an ecu? ie even if all the pipe work and valves check out could the problem be electrical?
 
  
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7867
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Sat Sep 01, 2018 9:32 am    Post subject: Reply with quote

Griffter wrote:
Is the system passive, or are any of the valves operated by an ecu? ie even if all the pipe work and valves check out could the problem be electrical?


It seems to be passive with the exception of the purge valve which just stays open with ignition on.
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7867
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Sat Sep 01, 2018 5:11 pm    Post subject: Reply with quote

Minor update, I made it to the overnight stop at Gravesend ready for Brands in the morning. I stopped after 30 minutes driving to check the tank cap and there was a little air rushing back to the tank but no more than I would expect in warm weather. Drove the rest of the way, some 2 hours further and did the same test and got the same result of just a little air bypassing the tank filler.

I think the next test it to take it for an emissions test at my local MOT station and see what happens.

Ideally I could do with running the car to zero miles on the range to make sure I don't run out of fuel before it hits zero.
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7867
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Fri Sep 14, 2018 10:00 pm    Post subject: Reply with quote

Probably a bit of closure on these issues that have caused me problems over the last few years,

I took the car to my local MOT station, where I usually get it tested and had it put on their machine to test the emissions. I usually struggle to pass and have done for the past few years, until we get the engine working really hot but today it went through no problem.
As this is now passing the emission test I also hope that the altitude problem has been cured.

Ignore the first result, he tested it with the engine not fully up to temperature.




It still can't fathom why the tank breather was disconnected or when I reconnected it it shrunk the tank but just checking everything and putting it back together must have cured it somehow Dont know

I also have run the tanks range to 15 miles so far and I haven't ran out of fuel yet, I will run it to zero to double check there was no lasting damage to the tank.
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alex yates
Brands Hatch
Brands Hatch


Joined: 06 Mar 2014
Posts: 14288
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Fri Sep 14, 2018 10:25 pm    Post subject: Reply with quote

thumbsup
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Dammit
Kyalami


Joined: 23 Sep 2016
Posts: 1840



PostPosted: Sat Sep 15, 2018 12:19 pm    Post subject: Reply with quote

I've "fixed" a number of things by taking them apart and putting them back together again - most recently an irrigation pump. No idea what was wrong with it, and no idea why it started working again after I'd stripped, cleaned and reassembled - other than maybe the tolerances were just slightly too wide beforehand.

It's a fairly unsatisfying way of fixing something, but if it works it works I guess.

My C55 Estate is currently with the garage, £1,100 later and they cannot say whether they've found out why it's now stalled twice. Hopefully it won't do it again, but given that we can't point to what caused it I'm not so hopeful
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alex yates
Brands Hatch
Brands Hatch


Joined: 06 Mar 2014
Posts: 14288
Location: The Ribble Valley, Lancashire

2000 Porsche 996 Carrera 4

PostPosted: Sat Sep 15, 2018 12:51 pm    Post subject: Reply with quote

My last car - a CLK, once every 12 months would start constantly reving on tickover permanently holding the revs between 1500 - 2500 rpm. No fault codes would come up, but reset the ECU with the code reader and the problem was cured for another 12 months. Very odd in deed!
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7867
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Thu Oct 04, 2018 11:27 pm    Post subject: Reply with quote

Well it's been driving fine recently but the other day I had a few issues where it felt like I was running out of fuel, (but showing 150 miles range) I pulled over and put £25 in it just to top it up but then the same kept happening for the rest of the drive home, it kept stalling but then would restart. I had been running with the fuel cap loose as there had been some signs of an issue and I didn't want to take any chances.

But the next day when I put the key in the ignition I had the fuel sender failure on the dash again so today I stripped it all down (again) and found the sender a bit of a struggle to get out of the tank and when I did I saw it was bent again, just like the last one.

Once I wiggled it out I also noticed the tank had shrunk and quite badly, looks like a new tank this time as it's quite misshapen.

There must have been a good vacuum to do this, that is the bottom of the tank showing through the fuel level and the reason it was running out of fuel was the pump was pulled up with it what



I have also ordered a new fuel filler vent valve as this must have caused this problem again.

I didn't recently do some altitude testing and got to 2650m up with out a problem, so something is working along with the emissions now being correct but the tank venting is causing other, costly problems. frustrated
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Last edited by infrasilver on Fri Oct 12, 2018 1:30 pm; edited 1 time in total
 
  
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MisterCorn
Long Beach


Joined: 08 Jan 2011
Posts: 6252
Location: Nottingham, England

2004 Porsche 996 Turbo

PostPosted: Thu Oct 04, 2018 11:50 pm    Post subject: Reply with quote

I hope you get to the bottom of it soon. Certainly an unusual problem.

MC
 
  
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911munKy
Nürburgring


Joined: 26 Nov 2014
Posts: 461



PostPosted: Fri Oct 05, 2018 8:08 am    Post subject: Reply with quote

Could there be an object floating around in the tank that occasionally blocks a vent and causes the suction issue? This problem might then go away when the fuel cap is released and fuel added only to intermittently repeat itself later.

Sorry but it’s a while since I read the thread so not sure if you had already checked for that.
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7867
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Fri Oct 05, 2018 12:14 pm    Post subject: Reply with quote

The tanks vents from the top through the sender unit so there is nothing to block lower down in the tank.

I still never found where the mystery pipe went from the carbon canister so if I'm removing the tank hopefully I can now trace it.
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deMort
Zolder


Joined: 21 Mar 2015
Posts: 5342
Location: Brighton


PostPosted: Fri Oct 05, 2018 7:33 pm    Post subject: Reply with quote

All the stuff i have are for USA markets and there is different items fitted there so not that helpfull .. ill send it if you want but will need an email addy .

No.3 in the picture .. have you replaced or swopped this with a known good ? this can cause an issue .

System is sealed , fuel being pumped out needs to have air added or the tank will collapse , as far as im aware this is done via no.3 .

Your pipe .. i think it goes back to the fuel tank .. but im afraid its not a system ive taken much notice of .. i just seem to remember a pipe under the bodywork on the tank i replaced many years ago ... that was due to a leak though .

Ive only ever seen this once and it wasnt my job to fix it but no.3 was replaced along with the solinoid valve although thats not really to do with this fault .. thats more of a filling related fault .

If number 3 has been replaced then the canister itself might be faulty .. i have no idea how they work internally .

The engine valve imho cant cause this to happen but logically thats the place it will vent through .. if that valve fails there will be a fault code for it .. the car is well aware when tank venting is happening and if it doesnt it will flag a code .
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7867
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Fri Oct 05, 2018 10:27 pm    Post subject: Reply with quote

I did replace pipe #3 with a good one that tested fine but there was carbon particles in it from the canister so I discounted it and bought a brand new check valve and fitted it inline, making sure the diaphragm flowed air the correct way.

The Carbon Canister was also swapped out just for the sake of it really and they don't really do a lot other than catch fuel vapour. You can blow through any of the three ports and they blow out of the others, basically its an open space with bits of carbon in it.

One of the mountings on the vent valve at the top of the filler tube has broken so when I change this I hope that cures the latest issue.

Like I said it was running fine for a while but I drove the D996 in France and the surface was soooo bad it killed the car to some extent, the headlight stopped working because the plug at the back came loose, the drivers door window stopped dropping again when closing and my EVAP issue came back with a vengeance. nooo
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Last edited by infrasilver on Thu Oct 18, 2018 10:24 pm; edited 2 times in total
 
  
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deMort
Zolder


Joined: 21 Mar 2015
Posts: 5342
Location: Brighton


PostPosted: Sat Oct 06, 2018 4:02 pm    Post subject: Reply with quote

To be honest you probably know a lot more about this system than me .. ive never had a fault with one and have never read up on it ..

One thing that strikes me though .. i have removed these before many times .. a/c pipes etc .. ive never seen carbon in the lines ..

Is it possible the line to the engine is blocked with carbon .
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7867
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Sat Oct 06, 2018 4:27 pm    Post subject: Reply with quote

I only know all about these as I've had no choice but the read everything I can about it. I will probably add something to the 996 FAQ's once I'm done.

I think the carbon bits in the pipe were from when it was shipped with and connected to the carbon canister and the bits had just gone into the pipe and I didn't feel like I should use it as it may have caused further problems, so discarded it.
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7867
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Fri Oct 12, 2018 2:49 pm    Post subject: Reply with quote

I have eventually got the fuel tank out and on the deck, it was a bit of a nightmare and very tight trying to get it out from between the subframe rear rails.

Once I got the plastic covers, cross braces and tank skid plate off I could see how much the tank was gurning, I would guess it's half its original capacity now.

The base should be flat.


After dropping the subframe, steering rack and 6 coolant hoses I dropped the tank off its cradle.



This was the nightmare bit, the tank wouldn't fit between the subframe rails so a big foot and a lot of kicking eventually saved me dropping the whole subrame and suspension off the front.

How I will get a full size tank back in is anyone's guess.

So with the tank off I could see places I have never seen before and treated a little bit of surface rust and the seams with POR15.





I also noticed my power steering pipes were a bit crusty near the end joints so these got cleaned up and more POR15 coated on them. I also did the brake pipe that runs across the front of the steering rack as this looks a nightmare to get to to with everything still in place.





And the tank out.


The new tank arrived today so will start refitting everything over the weekend, got a used one for £33 rather than pay the OPC price of £2000!
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Last edited by infrasilver on Fri Oct 12, 2018 3:37 pm; edited 1 time in total
 
  
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Stotty
Silverstone


Joined: 17 Dec 2009
Posts: 136
Location: Surrey


PostPosted: Fri Oct 12, 2018 3:28 pm    Post subject: Reply with quote

£2k Surprised Floor

Taking the piss.
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Ghianightmare
Monza


Joined: 25 Apr 2017
Posts: 158
Location: Dublin


PostPosted: Fri Oct 12, 2018 4:51 pm    Post subject: Reply with quote

Have you figured out where the 3rd pipe from the canister goes to? Is it just ambient? If it is, should it have a little filter on it?

Have you considered a new fuel cap for the replacement cap? Can’t remember if I asked you that previously.
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infrasilver
Fast & Furious
Fast & Furious


Joined: 04 Oct 2010
Posts: 7867
Location: East Midlands

2001 Porsche 996 Targa

PostPosted: Fri Oct 12, 2018 5:25 pm    Post subject: Reply with quote

Ghianightmare wrote:
Have you figured out where the 3rd pipe from the canister goes to? Is it just ambient? If it is, should it have a little filter on it?

Have you considered a new fuel cap for the replacement cap? Can’t remember if I asked you that previously.


I have so far traced the pipe to the rear of the car where there is another connection under the car and then goes up to what looks like the rear of the engine, so I'm now assuming it goes to the engine but as the car is still on the ground at the rearI can't trace any further at the moment.

The fuel caps only usually cause problems if they don't seal when the rubber seal degrades and cracks, mine seems like it seals very well.
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maldren
Österreich


Joined: 07 Oct 2016
Posts: 923



PostPosted: Sat Oct 13, 2018 8:37 am    Post subject: Reply with quote

Have you tried an airline to see if you can blow the old tank back to shape?
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2003 996.2 C2 Coupe Arctic Silver
 
  
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