BJ40 vacuum in fuel tank?

[brianblack138]

I’ve finally got my 1982 BJ40 to the point where I can reliably use it as my daily driver. As I rack up the miles, and refill the tank with diesel, I’ve noticed that when I take the fuel cap off the tank sucks some air in indicating that the tank is under vacuum. On all of my other diesel vehicles, the fuel cap allows air into the tank so that there is no vacuum. I suspect that this is a replacement fuel tank cap that was originally for a gas vehicle. Am I safe to drill a small hole in the cap to let air in to the tank or would this be problematic?

 

[DEADSALT]

venting system for tank is contained behind panel at bottom of b pillar passenger side.

drilling a hole in the cap would be like puncturing a hole in a tire to fill it up.

 

[brianblack138]

venting system for tank is contained behind panel at bottom of b pillar passenger side.

drilling a hole in the cap would be like puncturing a hole in a tire to fill it up.

Maybe it should be but It’s likely that it isn’t. I’ll check again. This is a 1982 BJ40 with a B engine (not a 3B) that was bought in Cartagena in 1983. It went through eight owners before I bought it and had a shop in Bogotá take it down to the frame to restore it. Diesel cruisers are very rare there, so there is no telling whether or not they left the vent line in place.

 

[roscoFJ73]

I dont know what fuel cap you have, but with Landcruisers, they dont differentiate between diesel or petrol when you buy an OEM or aftermarket.

 

[brianblack138]

I dont know what fuel cap you have, but with Landcruisers, they dont differentiate between diesel or petrol when you buy an OEM or aftermarket.

Thanks. As DEADSALT said, the correct solution is to find the tank vent hose and make sure it isn’t plugged. It’s not by the B pillar but I can start at the tank and trace from there.

 

[brianblack138]

I think I fixed it. I blew out all of the vent lines with air and made sure they weren’t crimped off. I’ll have to wait until I resolve my other issues to see if it solved the problem completely, but at leas I now know the vent lines and one way valve are working.