Fuel tank breathing "carbon can"
Discussion
Chaps, wonder if anyone can help me?
On the breather from the fuel tank, there's a "carbon can" with a solenoid on the top.
Are these things glued together normally, and does anyone know where I could get a new one?
Cant get it apart without splitting the plastic case, and while I'm down there I want to change the fuel filter. Does anyone know the part no. for the filter and where to get it??
Cheers Foxy
On the breather from the fuel tank, there's a "carbon can" with a solenoid on the top.
Are these things glued together normally, and does anyone know where I could get a new one?
Cant get it apart without splitting the plastic case, and while I'm down there I want to change the fuel filter. Does anyone know the part no. for the filter and where to get it??
Cheers Foxy
Why are you trying to open it, its just a charcoal cannister, not a lot to go wrong with it??? I have mine removed from the car, so will have a look at it this weekend for if you like. I'm sure the old fuel filter will have all the details you need writen on it to replace it, just remove it and give it a wipe......
Thanks Longbow
I'll leave the can alone I think. The problem I've got is the fuel tank not venting, so thats why I was looking at the can.
The vent pipe from the tank goes into the solenoid valve, which allows air flow into the can, which can then vent to atmosphere.
When does the solenoid operate, and if the solenoid was faulty, would it cause vacuuming in the tank??
I'll leave the can alone I think. The problem I've got is the fuel tank not venting, so thats why I was looking at the can.
The vent pipe from the tank goes into the solenoid valve, which allows air flow into the can, which can then vent to atmosphere.
When does the solenoid operate, and if the solenoid was faulty, would it cause vacuuming in the tank??
Rich, you really need to get hold of the service manual on cd.... it has all of the technical bulletins on it too, and info on all these subsystems such as the vent solenoid etc... As an electrical engineer, you'd have no problems using it - it even has all of the electrical wiring diagram for the car, including all pin-outs etc. In response to your question, as taken from the cd, the purge valve drive is pin 13 on the engine harness connector. This powers up the purge valve any time the fuel pump is working. There was a techincal bulletin out in Sept 1997 directing a change to drive the purge valve via the engine ECU, as oppose to earlier it was driven by a direct ignition live. So yes, you are right, if your fuel tank isn't venting then it is most likely the purge valve not operating for some reason. You could check whether you're getting a voltage across it with the fuel pump on (i.e. ignition circuit armed) and take it from there. From memory there is also an inline device in the vent tube behind the fuel tank, not sure what that does or if its powered, but can investigate that this weekend for you.
Cheers Windsor,
Just put 12vdc (450mA) across the valve and it works perfectly.
Looks like I'll have to check the supply for a 12v feed tonight. A wiring diagram would make things much clearer for me.
Where did you get your CD from? Did you approach a dealer or TVR? Thats something I could do with.
Rich
Just put 12vdc (450mA) across the valve and it works perfectly.
Looks like I'll have to check the supply for a 12v feed tonight. A wiring diagram would make things much clearer for me.
Where did you get your CD from? Did you approach a dealer or TVR? Thats something I could do with.
Rich
I got my cd from the previous owner who did his own servicing, like me. We need to get this cd out to people who need it as it really is helpful. Nowhere near as good as the workshop manuals for my MR2 from Toyota, but useful enough if you are quite handy. There is more on the cd I had than just the engine setup software. All the TVR service bulletins for Chims, Griff, Cerbs and Tuscans are on this, and it makes very interesting reading!!! Some of the engineering cock-ups are monumental!! Also, the servicing schedules and workshop manuals too for the cerb. Although I have an Engineering degree, my electronics is pretty crap so we could do with someone clued up in the electrics department on here. Send me an email and I'll pass you onto someone who can lend you the cd.
b6uch said:
What syptoms do you get to know the tank is not venting properly?? I ask as i have a problem and i'm trying to work out if it could be something like this!
Had the problem for a while now! Its mainly a starting problem, but not a hot starting problem. Ive changed the plugs, leads etc.
If I try starting the car when hot(after just turning off), it starts. If the cars left for a few days, itll start straight away from cold. If its anywhere in between, it takes about 30 seconds of turning over to start it up. Coupled with this, I have a negative pressure in the tank(suction when removing the cap).
I think the pump is trying to draw fuel from the tank, and because the tank isnt venting, instead of positive suction on the pump, there is negative pressure in the tank and therefore, the pump suction. When the system cools and has enough time, I think the negative pressure in the tank is drawing fuel back from the fuel rail, which is why it may take so long to start.
Its not an ignition fault, when I have fuel she fires straight away. Its not positive pressure in the tank because ive tried running with a loose cap (in which case it would blow out.
Does that make sense?
>> Edited by foxy4200 on Wednesday 5th October 17:46
Had a similar problem with mine. It would start well from cold and also if it was left for more than an hour. But if you tried to start it when hot it would tick over very lumpy and sometimes die. I fitted a new fuel filter and checked the purge valve, also made sure the canister was as high in its mounts as it would go as read on here it needed to be, not sure why? Anyway changing the filter sorted it. I have fitted a fuel pressure gauge to the fuel rail so next time I'll know whats going on.
diycerb said:
You should get 12v at the pins of the solenoid when the ignition is switched on. Rich.
With the ignition switched on I've got 0 volts at the pins of the solenoid, but when I start the engine I get 12 volts, so the system only purges when the engine has already started..
Think I'll have to wait for some drawings!!
If anyone has a copy of the CD mentioned above I'd be very grateful for one. I run an electronic design company and would be happy to advise on electrical matters if I had the relevant information.
Also, if anyone has any dead 'black boxes' kicking around, I'd be happy to reverse engineer them to get the schematics from these. Having the wiring info is only part of the story, you need to know what goes on inside the boxes too. Who knows, might even be able to develop this into a cheap repair/test service!!
Also, if anyone has any dead 'black boxes' kicking around, I'd be happy to reverse engineer them to get the schematics from these. Having the wiring info is only part of the story, you need to know what goes on inside the boxes too. Who knows, might even be able to develop this into a cheap repair/test service!!
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