We are having alot of problems with vapor locking in a '68 F100 with a 300 inline 6 cylinder. Have insulated and re-routed the fuel line. Does anyone have any suggestions? It is still vapor locking.

 

J Welcome to FTE and the Bump Forum.

Vapor locking is a term from bygone years, I suspect you have a different problem with delivery. Have you changed filters, checked for trash blockages etc.?

Pull your gas line near the carb, along with the coil wire. Put the gas line into a clear empty water bottle, and have someone spin the engine over while watching the gas flow.

You may very well have a small piece of rust blocking the flow, the pump may need replacing.




John

 

Thanks. Have already done those things. I guess when you are from a bygone era like me, you still use the terms.

 

maybe it's not vapor lock , as rerouting and insulating should have fixed it .
what exactly is it doing ??

 

J62, Does your exhaust manifold have heat riser butterfly . If so make sure that it is free to move. If it has one and is frozen closed it will cause the fuel to boil in the carburetor. One other thing to try if in fact that heat is causing the problem I have seen someone fashion a piece of aluminum as large as possible as a heat shield between the carburetor and manifold. Many years ago I saw a small electric fan mounted to blow air on the carburetor of a Datsun B210 that was factory installed! What type fo air cleaner are you using? Is it the one with the snorkle and butterfly that is operated by a small thermostat ? I have seen a lot of 300 s that have exhaust leaks between the head and manifold or between the intake and exhaust manifold where they are bolted together. My brain is empty now.
Kenny