Fuel Leaking From Carbon Canister When Tank Full

[Therambleman]

Dear knowledgable folks!

Just want to know if this is an issue for my 260 as I'm a bit of mechanical noob. Tried searching the forums already but not much luck.

 

When I fill the fuel tank to capacity, I've noticed a fuel smell from the car when I'm parked. I assumed this was the return line to the carbs (triple webers) and never thought much of it, just always try not to overfill the car.

 

Today, I filled the car, but then parked it facing down a hill. 2 minutes later I noticed a bit of fuel on the ground, opened the hood and saw fuel leaking from all around the Carbon Canister / emissions filter thing. 

 

Is this OK? Should fuel be able to overflow from the canister? If not – should I fix it? What implications are there to a stuffed / leaking carbon canister?

 

Any advice / help greatly appreciated!

 

James

[Enzo]

Fuel should not come out of the Carbon Canister. It is connected to a line that runs back to the top of the Expansion tank . (Highest point of the system). This should only have fume.

    Have you had the canister disconnected and attached it to the fuel tank return line by mistake.

The 260z has 3x lines running back to the rear: Fuel Line: Fuel return line and the Fuel hose from the canister to the top of the expansion tank.

Haynes Manual  Page 43 . ( Chapter 3 Carburation: Fuel and exhaust system).

Beware of fire if the fuel leak continues. Do not drive till sorted.

David.

[Therambleman]

Thanks for your help, David. And also for bearing with me as a lot of this is new to me!

 

Update: As you suggested, I'm trying to figure out which is the fuel return line, and which is the hose from the canister – so I can figure out if they are connected to the wrong bits on the carbon canister.

 

- How do I know which is which? At the moment, the line furthest from the engine is running to the 'From fuel tank' on the canister. (page 69 Haynes) 

Pic of the three lines as described: http://i.imgur.com/zp7SXcg.jpg

The furthest line from the engine is the one connected to the "from fuel tank" http://i.imgur.com/HMkqdjE.jpg

 

ALSO:

 

- Having a closer look – it appears my vac purge control line is not connected. As I understand it – this is due to the installation of the webers. So that shouldn't be a problem. The webers were installed by a datsun specialist who was recommended to me so he would have done that right. 

 

- Also the purge control valve diaphragm doesn't seal properly. (Haynes Manual page 68). As this line isn't connected anyway (due to webers) I guess this doesn't matter? Not sure about this.

- Also I stress, this happened after I essentially over-filled the car and then parked it facing DOWN a hill so the expansion tank may have dripped fuel to the canister and out of the broken diaphragm? The car runs great performance wise. Does that make logical sense to someone that actually knows what they are talking about??

 

Thanks guys – always stoked by the time people are willing to give to respond to questions like this

 

James

[Enzo]

Ok. The expansion tank is above the fuel filler neck so you would have fuel coming out  before it got anywhere near the expansion tank.

  The middle fitting on the carbon canister should be to the manifold vacuum on the original SU/Hitachi balance tube. It looks like you have it fitted to the fuel return line. If this is the case when you overfilled the tank and parked it nose down hill the fuel would have flowed through the pipe to the vacuum canister.

Yes the smallest pipe (furthest from the engine) is the vent outlet back to the expansion tank.

The fuel return line that appears to be hocked up to the carbon canister can be blocked off or you can have a return line from the carbs plumbed into it. Your choice. If the carbs are running fine just block it off.

Hope this helps. Bit hard to trace your lines from the pictures.

David.