Fuel Tank Vent

[94rangie]

I lost the fuel tank cap on my '72 IIa (OK, I left it on the top of the rear tire when I filled up and forgot to put it back on.) I got a new cap that fits very tightly and doesn't seem to allow the tank to vent, or more importantly causes the engine to create a vacuum. The vacuum gets so strong the engine dies or will not maintain "higher" rpm/loads and the cap is hard to get off. Once I get the cap off I can hear the tank "ka-****" as air is let in.

How is the tank supposed to vent? This is the stock tank under the passenger seat.

Regards,
Larry M.
'72 IIa LHD
'94 RRC SWB

[sayers]

On my 74 there is a vent hose coming out of the tank going under the drivers seat to an overflow tank, then a hose up to the char. cansiter in the engine compartment. Not sure if your truck is set up the same way, just any idea. good luck

[Tim Smith]

Do you fill it under the seat or from the outside. Mine are military tanks, filled from under the seat, and there is no vent system outside of the cap. Could be you need a vented cap?

[LaneRover]

I lost the fuel tank cap on my '72 IIa (OK, I left it on the top of the rear tire when I filled up and forgot to put it back on.)

I've done that! Now I always leave the cap on the tire on the hood so I can't drive off without seeing it!

[xsbowes]

On the 70 IIa I had the caps were chained to the filler extension. Same with the lightweight I have now.

[sven]

On my 74 there is a vent hose coming out of the tank going under the drivers seat to an overflow tank, then a hose up to the char. cansiter in the engine compartment. Not sure if your truck is set up the same way, just any idea. good luck

Does anyone know if a 73 NADA is setup the same way? I have that vent hose going to the drivers side but it goes nowhere and just emptys gas on the ground when I overfill it.

[Leslie]

My '72 (I call it a NADA since it was built as a US-spec, but it's not a 2.6 6-cyl, it's a regular 2.25)... it had that system... it wasn't so much of an overflow tank under the driver as it was a pressure tank for controlling vapor/fumes, but yes, it then headed for the charcoal canister.

[gudjeon]

Well Larry, I may not be able to help with your venting problem. However, let me be the first to congratulate you on an air tight fuel system. Some have struggled many a moon to achieve such a feat. :D

[SafeAirOne]

There are many types of fuel caps. I BELIEVE that some are vented and some are not. Make sure you have the correct type. I'd be willing to bet that the charcoal canister-type are not vented (since the idea is to have all fumes pass through the canister and NOT vent unfiltered to the atmosphere, killing polar bears).

Our hosts will know which cap you need. See: http://www.roversnorth.com/store/c-36-tanks-filler-assem.aspx

[sayers]

Does anyone know if a 73 NADA is setup the same way? I have that vent hose going to the drivers side but it goes nowhere and just emptys gas on the ground when I overfill it.

I have the same problem when I try and top of the tank, I like how the overflow gas goes right down onto the exhaust pipe. I finally learned not to do this, I am not sure why land rover set this system up like this, any help out there ?

[thixon]

I have the same problem when I try and top of the tank, I like how the overflow gas goes right down onto the exhaust pipe. I finally learned not to do this, I am not sure why land rover set this system up like this, any help out there ?

It sounds like your truck had a vapor recovery system (charcoal filter) at one time, and someone has removed it. Usually, these system operate using a non-vented gas cap. pressure is equalized via the system. Now, your truck is venting via the tube with nothing connected to it, and thats dangerous. You're about to start a big fire.

Two options:

1. Go to Napa/Auto Zone/Oriellys/allthesameanyway and buy a charcoal filter for a vapor recovery system, and some tubing and then rig the thing up. This won't be so easy, because they'll want to know what make and model so their super computer can id the part for them. I miss the days of the auto parts store employing people who actually knew how to work on a car.

2. Call our hosts and ask them for a vented gas cap for your truck, and cap off/get rid of that open line.

Hope this helps.

[sven]

I dont think the charcoal canister is gonna help. Mine is missing too. But the problem of fuel pouring out happens when you fill up...so the cap is off. Doesnt happen while driving.

Does anyone know if a fuel catch can of sorts is supposed to be at the end of that tube?

[greenmeanie]

Have a look on the forward inside part of the driver's side (LHD) rear wing. There should be a small tank in there that acts as an expansion/catch system. The hose ios supposed to come off the main tank, run across the truck to the expansion tank and then on to the charcoal canister.

[sven]

Yup Im missing all that stuff. There's a good diagram and description of the evaporative setup in teh Haynes manual. So it looks like thixon's #2 idea would be the best solution for me.

Anyone know how to tell if my gas cap is vented or non-vented? Im wondering if the PO ever switched it for a non-vented.

[TedW]

..in the center of the lug side of the cap. Only drill through one layer of metal. You now have a vented cap. I did this in '91 and it has worked great.

[sayers]

It sounds like your truck had a vapor recovery system (charcoal filter) at one time, and someone has removed it. Usually, these system operate using a non-vented gas cap. pressure is equalized via the system. Now, your truck is venting via the tube with nothing connected to it, and thats dangerous. You're about to start a big fire.

Two options:

1. Go to Napa/Auto Zone/Oriellys/allthesameanyway and buy a charcoal filter for a vapor recovery system, and some tubing and then rig the thing up. This won't be so easy, because they'll want to know what make and model so their super computer can id the part for them. I miss the days of the auto parts store employing people who actually knew how to work on a car.

2. Call our hosts and ask them for a vented gas cap for your truck, and cap off/get rid of that open line.

Hope this helps.
I have an all orginal 88, it has the charcoal canister and all piping or tubes, it also has the orgin. cap, I was thinking just not fill or try to fill it up all the way when the pump kicks off the first time. I am thinking that the tube may be off or cracked, maybe need a new hose to the expansion tank, I'll have to investigate further. thanks

[thixon]

I have an all orginal 88, it has the charcoal canister and all piping or tubes, it also has the orgin. cap, I was thinking just not fill or try to fill it up all the way when the pump kicks off the first time. I am thinking that the tube may be off or cracked, maybe need a new hose to the expansion tank, I'll have to investigate further. thanks

Sayers,

If it were me, I'd do exactly what you mention and look for leaks. You can just stop filling the tank full to stop the leaking, but if you rolled while wheeling you could start a fire. Thats always a possibility anyway, but why add another variable to the equation?

Remember, there's no reason you have to run with all that installed. You could just rip it out, get a vented cap, and cap off the elbow in the top of the tank that ran to the venting system.

[sayers]

Sayers,

If it were me, I'd do exactly what you mention and look for leaks. You can just stop filling the tank full to stop the leaking, but if you rolled while wheeling you could start a fire. Thats always a possibility anyway, but why add another variable to the equation?

Remember, there's no reason you have to run with all that installed. You could just rip it out, get a vented cap, and cap off the elbow in the top of the tank that ran to the venting system.

travis, that a good idea, I will let you know what happens, I am just trying to keep the rover as orgin. as possible. thanks again.

[sayers]

Sven, I took the rear access panel off from under the rear left wheel well, this gives you access to the expansion tank, I had a loose hose, you might check this out. good luck.

[Jeff Aronson]

There are caps that are vented and unvented. Series II-A's have the overflow and need the vented cap. It makes sense that the Series III would be a non-vented cap; the whole idea was to trap the vapor in the system, and thus the charcol canister.

I fill the tank slowly and pay attention to it's likely amount needed to fill. I haven't had an overflow since then. I wonder if the military dual tanks create different dynamics.

Jeff

[94rangie]

..in the center of the lug side of the cap. Only drill through one layer of metal. You now have a vented cap. I did this in '91 and it has worked great.

Is the lug side from the outside or the inside?

[Jim-ME]

It's the inside. I had to make my unvented cap vented by drilling a 1/32 hole in the center of the cap thru the first layer of metal. You don't want to drill thru both layers because rain, snow melt and crap can get in.
Jim

[94rangie]

Thanks. I took a closer look at it today and it all makes sense. I'll drill it out tomorrow.

Larry