41 replies to this topic

[TerrA LX]

this was my fear with relocating my canister.
are all lines connected correctly.
is your canister in the orig. location.
are you running that (dont know name of it) thing at the rear that the HZ runs or just hose and pipe to the canister.

[TerrA LX]

its hard to describe the HZ thing, but i think you need it with a drop tank, if you can get your hands on a manual or stick your head under one you will see a little tank type thing joining both sides of the tank hoses then one hose from that to the canister.
HZ thing is about three inches long, an inch wide and two inches deep and is located between the diff and the tank standard. approx. three hoses connected to it.
i think its on the forum somewhere.
pretty sure you need it with a drop tank tho.
maybe PM Yella SLuR or someone. He just done a big write up on drop tanks.
let me know how you get on thanx.
cheers T.

[ls2lxhatch]

The fuel tank breather is connected to the canister. When you fill the tank the fuel coming out of the pump typically cooler than the outside temperature. As the fuel warms to the outside temperature it expands and air in the fuel tank is released to the canister. If the fuel expands to the point where there is no air left in the tank then fuel will be pushed out of the canister.

[ls2lxhatch]

Yes, I think the problem is caused by over filling the tank. You will notice that most cars have a sticker advising you not to overfill the tank, I suspect for this reason. I had the same problem with my drop tank. If the fuel expands by 5% in a 120 litre tank then that is an extra 6 litres.

The fuel should have come out of the bottom of the canister and not puddled around the base. The canister may have a split.

[TerrA LX]

so long as it is the same config, i think yes, argument would be that it is a direct replacement for obsolete part.

[Toranamat69]

All LX's have (or should have) the vapour trap between the tank and the charcoal canister. These are mounted up above the diff housing.

When I first had my LX on the road, I had the HP fuel return from the fuel rail T'd into the 3/8 breather on the drivers side of the tank and it was leaving puddles of fuel out of the carcoal canister just as you say. It was actually doing whilst driving around too
I ended up just disconnecting this line to the vapour trap and only used 2 of them.
The fuel return goes straigt to the 3/8" breather and it has worked a treat ever since.

I doubt it is from over filling, on a level ground I can fill my tank until it is lapping at the top of the filler neck and it doesn't spit out the charcoal canister now that I have separated the fuel return from the charcoal canister line.

You can mount the canister under the guard (thats where mine is) as long as the pipe still goes up and over as high as you can run it under the guard - try to achieve at least the same height as standard. this stops your tank partially draining if you park on a steep slope.

I use a canister out of a VL Commo which suits an 80 odd Litre tank and funnily enough is the identical part used on Nissan Pulsars with a 50L tank. These are a bit smaller than the Torana ones.

M@

[TerrA LX]

vapour trap
thanx Toranamat69, thats the word i was looking for.

[TerrA LX]

can someone post a pic from the parts book posted here?
im pretty sure there is a factory drawing in one of the manualls.

[ls2lxhatch]

The junction box above the tank has three inputs connected to the tank breathers and one output connected to the canister. Mine is out of the car at the moment and it rattles so I suspect it has a float inside that is designed to prevent liquid fuel from entering the canister

Page 12 of the supplement section of the Gregorys LH-LX manual has the following statement. "A dome built into the fuel tank prevents liquid fuel entering the canister when the tank is full or the vehicle is parked on an incline." I assume that they are actually referring to the junction box fitted outside the tank.

It would be reasonable to deduce the following.

1. The 120 litre tank is filled with petrol at around 15 �C from the underground tanks at the fuel station. ( 15 �C is the industry standard for fuel in underground tanks.)

2. The petrol in the tank is heated to the ambient temperature of 25 �C. Petrol expands and contracts at 0.0011 of its volume per degree Celsius variation.
http://www.consumer....el_tempcomp.pdf

3. The 120 litres expands to 122.64 litres resulting it 2.64 litres of fuel wanting to leave the tank under pressure.

4. The junction box fails to prevent the 2.64 litres of fuel leaving the tank and floods the canister. The junction box fails either because it is faulty or it can not handle the pressure created by the expansion in a 120 litre drop tank.

[TerrA LX]

you read my mind and put it to words AndyCullen
can we avoid this by
A; fitting and maintaining said vapour trap and
B; only fill the tank to 90% capasity?

[hatchssv8]

My 2 cents worth gents.

With pressurized fuel systems (efi)
Always have the canister above the uppermost fuel level height. Not including the fuel rail at the engine.
During a purge cycle (driven by the ECU), the vapours in the canister are to be burnt in the engine, hence the term purge, i.e. no fuel vapour in canister.
The purging method employed is intake vacuum pressure placed directly on the cannister.
If you have overfilled (or have incorrectly placed the canister) the tank, it means there is no 'air gap' at the tank and the suction from the engine will start sucking fuel into the canister. It will continue to do so until he fuel level drops below canister.

I would suggest that the canister is plumbed directly to the filler pipe breather, and even then, do not overfill the tank. This is because the ECM may purge during acceleration and the subsequent sloshed fuel will be covering the breather at the filler pipe.

Hope this makes sence.

I had the exact same problem with my VR on one occassion. Overfilled for a long trip. Warmer weather than usual. ECM purged with tank full of fuel (no air gap). Canister sauturated until it leaked.********NOTE******* Even after I switched engine off, fuel was still being sucked into the canister. (like syphoning)

Remedy: Release fuel filler cap (careful of spray), remove hose from canister. This way the pressure (vacuum) is released to atmosphere.

Dont forget to clear the line of any fuel. (basically blow air from hosed removed at canister)

Hope this helps., Max

[Tiny]

Teriffic info gents!

Ive been suffering this problem since i installed my drop tank with no real solution.

I too found that anything over about 3/4 full tank results in expansion ( you can actually HEAR the fuel bubbling around and the tank expanding under pressure!!) and it pumps out the air breather lines and onto the ground in my case.
Not a good look at A) a car show B ) A wedding...

Now, I got a "special" valve from nissan which is from a patrol fuel tank.
It allows the movement of vapor but closes when liquid hits it. Except under pressure where it STILL pours out!

My old remedy is to open the fuel cap to release pressure!
( i'm running a Carter Black 110Gph 15psi pump with a mallory return regulator and return line).

I'm going to keep a close eye on this thread for further solutions to a frustrating problem ( even more frustrating when i have no room to put cannisters etc.. especialy above tank line!!)

Cheers

[ls2lxhatch]

The first thing to do would be to check that the fuel lines connected to the junction box are connected to breathers at the top of the tank and therefore only exposed to fuel if the tank is full. Make sure that the return line from the regulator is not connected to the breather system.

A possible explanation is that overnight the fuel in the tank cools and shrinks creating a vacuum which sucks air into the tank via the breather valve in the fuel cap. The next day pressure builds in the tank, the fuel vapour under pressure leaves the tank via the junction box and pushes out the fuel in the canister line from the previous overflow to the canister resulting in flooding. A three meter 3/8 line would hold a reasonable amount of fuel.

This should now mean that the system is now purged of fuel and the problem will not reoccur until the tank is filled to the point where fuel is again forced into the canister line.

You should be able to prove this for yourself by filling the tank. Parking the car in the sun with the line from the canister running into a fuel container. Once fuel has stopped running into the container then drain 20 litres from the tank. The next day I would expect to see fuel left in the canister line run into the container. The day after that I not expect to see fuel but I would expect to see bubbles if the hose was placed in fuel.