Hi sorry if this is already posted but am very new to forums.

There is a fuel leak from the charcole cannister when pumping fuel from one tank but when i press the tank change button it stops flowing from the cannister.

When leaking from cannister car runs rough untill higher revs but when switched to the other tank it seems to run fine.

Any ideas on what is causing the leak from the cannister when pumping from one tank but not when pumping from the other.

 

Are you sure it's the charcoal canister. My understanding is there should just be fumes going through there.

 

Thats what i thought too.......it is located in the front right gaurd infront of the wheel and it only leaks when the fuel change over switch is in the clicked in possision also when its not leaking when the fuel switch is in the clicked oout position the car runs like crap......when the fuel swich is in the clicked in position and it is leaking fuel i can hear a pump in the back left of the car

 

I have an idea. It does not quite fit the scenario on your car. Partly, because, I'm not
aware as to whether your 76 has carbs or is fuel injected. As the carb cars have two fuel pumps, each imbedded n a tank and the FI cars use only one, external and the rear of the boot, it might make a difference as to what is wrong.


The charcoal in the canisters can become saturated by processing fumes over decades and loose that function. The material just solidifies.


The canisater is a sealed plastic can. So, he leak is probably not there, Unless pierced by road debris ore something. That leaves the hose that comes in from the tank vent apparatus, itself rather convoluted, and the hose entering the engine bay to the purge valve. I suspect there is a break or more in a hose.


The canisters are a GM design and used in many USA cars.


They can also be cut open and recharged with clean charcoal and resealed.


Carl

 

Ok so update......it is a duel carby model....i have established so far that the fuel pump in the drivers side tank (RHD) is shot......thats y it will only run on the left tank ....i have also found out that as soon as i connect all of the pipes up on the charcol tank the car will stall. I have also blown air into the pipe that ruturns to the tank from the charcol canister and have established that it is blocked.......do u guys think that the fuel return change over solenoid could have somthing to do with this charcoal return line being blocked and if so where do i locate it on the mark 1 with carby motor as i cant seem to find anything in the boot......im reali coming to my witts end with this damn thing....thanks all in advance

 

It is leaking out of the overflow pipe that comes out the top of the charcoal canister and goes into the very front of the engine bay

 

This is the pipe that the fuel is comming out of into the charcoal canister.....but if i block it the car stalls unless at high revs
the black hose at the front is the fuel feed....the yelowy colored one that my hand is on comes out of the top second steel pipe

 

Mabie if somone has a su carby model they could post a picture of where the fuel lines go in and out around the carbys please.....ita gotta be plumbed wrong or somthink

 

You have a stuck changeover or return valve. The wrong tank gets the return fuel until it fills up completely, submerging the vent can in the tank and sending liquid fuel into the vapor system until it pours out the vapor canister up front. It's been the fiery death of many dual tank Jags! Valves usually stick from tank contaminants (rust). Don't replace anything until the tanks are (very) clean!

 

As far as i can make out there is no return line at all......other then the breather from the charcole tank wich only goes to the passenger tank.....even if this were the case i have empyed the driver side tank more then half way to get the fuel pump out and as the pump os shot it only runs on the passenger tank

 

Minor update of i block the white line in the pic with my finger and leave the ignition on (but not running) the pump runs but because im blocking where the fuel has been leaking from......the fuel starts leaking out of the carby closest to the firewall......could this mean somthing in the carby is leaking that shouldnt.....like some sort of needle and seat or fuel bowel issue ......i dont even know if these su carbys have a traditional needle, seat and float set up????

 

Jake, I'm pretty sure you must have a S2, S1 doesn't have a charcole cannister or return lines to the tanks. Last S1 was built late 73".

Standard type needle & seat set up. Fuel bowl is bolted to the side of each carby.



SU HS8 Removing,servicing,refitting.pdf
SU HS8 Tuning and setting up.pdf

 

Thanks man that is the carb set up i have but there is deff lines going through the wheel gaurd into a canister in front of the driver front wheel(rhd).....also my vin plate says its a 1974......but thats not to say it may have had an engine swap at some point.....i will take some more pics and post them up in the morning.........thanks so much for the pics and link should help heaps........and hopfuly ots a needle and float issue, but i will keep everyone posted

 

Not in my lexicon. But, The engine cares not as to the tank vent system. That is a fueling and emisions issue.


There should be a hose from the canister to the intake manifold. Usually includes a valve to control the "purge".


The "needle and seat" control fuel delivery. Separate and apart from fumes venting.
Unless fuel delivery and vent systems are "crossed" as SLOFUT opines.


Just went out to my breezeway. 85 F. Usually much cooler than away from it. Hibernate is the plan. AC on and hope the power stays on..


Carl


Slofut has the most logical concept. SOLO

 

Ok every one i have worked it out....there was a tiny bit of debree in the needle and seat causing ot to over fuel......it still runs bad unles one pipe is left off the char cannister but i think that has alot to do with the heating pipe to it having a crack in it......thak u all for all ur help and guidence on this issue 😊😊😊

 

Thanks for the update Jake. Do let us know if the result changes. Enjoy your ser2 !