100 series petrol Landcruiser fuel tanks.

Is the cap supposed to breath? Or other breathing not working? Shouldn’t be a vacuum in the tank I would think.

The sub has a pump that feeds the efi pump. If it runs on main but not on sub, look for fuse issue. If not try removing the fuel cap. You can take the fuel cap apart and clean the dirt out of it. If it’s the vacuum causing the problem. Have you had the head serviced on the motor? There’s a valve on the inlet that can be plumbed the wrong way

So what exactly is the problem?

As I understand it, there is a small pump that transfers fuel from the sub to the main when you switch it on.

So is the pump working when turned on or not?

If it is and fuel is still not transfering then you may have a blocked filter on the pick up in the sub?

Don't forget about checking out the LCOOL (Land Cruiser Owners On Line) forum. You have to join but its free and there is a goldmine of information there about Landcruisers.

Bruno F
Do you really have a 182L tank in the space where a 46 L tank used to be? Has the sub actually been removed to fit the larger than main and sub OE tanks? They both total 145. 95 +50 I thought.
Like others, I would think the cap should breath one way, If not as Dozer mentioned, the breathing may be through that valve on the engine. If it is an aftermarket tank then it's wall strength would be the only reason the 182 Litres isn't far smaller because of vacuum. In the past I have seen a thin walled flat style car tank reduce from 80 litres to 22 litres. Different fuel pumps though. Best you sort the vacuum issue I reckon.

Just googled “Landcruiser fuel tank breather”, Bruno, and scored this photo. There’s a small white valve on the main tank, so may be one on the auxiliary?



Apparently the tank breathes out through this valve & in through the cap........
..or is it the other way lol?

Bob

Bruno,

I would check that the sub tank pump is getting power, and working, i know my v8 petrol cruiser 100 s failed there, and had to have the change over wiring loom replaced....$.1500.00 years ago!

Cheers Axle.

Thanks a lot to all who replied to my post. I won't waste forum space with individual replies. It really has helped me focus. To be honest, I'm procrastinating because it's cold here in Rockingham and easier to do research on the net than actually pull things apart!
Yes, I do have a 182L sub tank. The OEM 46l comes out, so does the spare wheel and the Long Ranger tank fits in most of the space. It uses the OEM pump and sender.
I can access the pump (torch and mirror job) and intend to firstly; see if it runs then pull it and check the filter. All evidence points to the tanks breathing in through the cap, I'd like Toyota to confirm that somewhere!
I got lots of dust out of my cap but still get a vacuum when draining fuel from the tank.
The google pic of the main tank vent line is very helpful as I've found nothing in my Toyota manual.
I've just joined LCOOL so will be hunting there for info.
I'll update when I know more.

Thanks RMD. Yep, I have two tanks and can carry 277 litres (needed to feed the V8 for long distance remote). I'm now pretty sure that the cap is the only way for air to get into the tanks and reckon mine is OK as the main tank feeds alright. I guess that I'm developing a partial vacuum when draining fuel as the rate is higher than the normal engine consumption. I'll probably shout it a new cap though, a lot of dust has been through the original.

Thanks Bob. The link was very helpful. I've learned a lot about the layout already. The cap seems to be the only air inlet for breathing, Mine is OK but I did clean out a lot of dust and grit. I've pulled the pump and checked it's filter, OK. It runs on 12 volts. Next was the shuttle valve, also OK. I guess it's time to delve into the electrickery!