77 MGB won't star hot

I have a 77 B, once in a while it will bogg down while driving and stall, will not start hot, after about 45 minutes it retarts and runs fine. This is very intermittent. Also does not to like to restart when hot. Just recently when sitting on the side of the road broke down, I heard the gas tank pop, pulled the cap and had alot of pressure. Thought vapor lock was the problem but it still did not start. It does have a Weber carb. Anyone have any simular problems or a solution. Thanks.

Your tank vent is plugged at some point. Would take a few moments after fuel starvation to fill the float chamber.

Just throwing it out there.

Its typical to see that with a rich condition, very common with the Weber DGV since the float height is usually incorrect when new. Try adjusting the float by the book, and you'll probably find the problem is resolved.

Explain a bit more.

Did the tank have pressure or vacuum?

Did the air whoosh in or out?

air came out, can anyone explain how to adjust the float height

Print this:
http://www.piercemanifolds.com/Float_Level_1.htm

With my SU's, vapor lock used to be a problem until I had the stock exhaust manifold Jet-Hot coated to keep the heat down under the hood. When I did have vapor lock, the car would start if I pressed the accelerator to the floor while cranking the engine.

If air came out, heat is pressurising the fuel.

Probably pushing it past the needle and seat and flooding it.

Been very common since ethanol has been introduced. I get the same problem in my 2 Bs with webers (both with the floats set correctly).

I think it is a flooding condition. I think (and can be totally wrong) that the ethanol is either evaporating or expanding the gas into the intake manifold, causing a rich condition. Flooring the throttle to open the throttle plates to get more air in always gets my cars re-started every time...followed by a huge black cloud out of the tail pipe. Again, only when the engine is hot and has been sitting a few minutes.

I NEVER had this problem before the ethanol was added. I could be totally wrong, but blaming the ethanol anyway!

Has anyone tried insulating the metal parts of the fuel line under the hood or the rest of the car? A length of rubber fuel line that has been split lengthwise and wrapped around the metal lines might be a cheap solution to try if it is safe.

Rubber absorbs heat and holds,it, so that wouldn't be ideal. You need an insulator, like 1" wide header wrap, or a ceramic heat sleeve as used on plug wires near headers. The problem is really the carb getting heat soaked more than the fuel line anyway, but I'd still bet the AFR is adjusted rich with a mal-adjusted float.

pulled top of carb. floats were in specs