Vented Gas Cap? (1 Viewer)

[kotoSA]

To the group

Ever since I got my 1980 fj43 I have had performance problems when going up highway grades. It acts like it is starved for fuel.
Have replaced
fuel pump
spark plugs & wires
New Manafree carb and distributor
added fuel regulator set at 4psi
fuel filter
No heavy particles in filter to cause one to replace gas tank or filter sock

A friend took the gas cap off and noticed that was under pressure. He thinks that it may need to have a vented cap. He thinks that when climbing the hill the fuel flow is limited due to a vacuum and when it is traveling with normal grades it equalizes fast enough to run somewhat ok.

Please I am at my wits end
Should it have a vented cap? anyone?

 

[78fj40mg]

Yes you need a vented gas cap. However, you may have emissions related issues as well.

Here's some reading on the subject: Search Results for Query: vented gas cap | IH8MUD Forum

 

[78fj40mg]

Also check tank venting

Page 168 Land Cruiser 40 & 55 Series Factory Gas Tanks

 

[JohnnyC]

When you say manafre carb ... Do you mean a weber?

 

[JohnnyC]

If you think it's a vent problem try driving with the cap off and see if it still happens