What can i add to the fuel on my 79 lincoln to stop vapor lock

Item Part Number Description 1 9D280 Fuel Injection Supply Manifold 2 9C968 Fuel Pressure Regulator 3 9F593 Fuel Injector 4 9350 Fuel Pump 5 - Vapor Valve 6 9002 Fuel Tank 7 9S278 Rear Fuel Supply Return and Vapor Tube 8 9155 Fuel Filter

Sounds like vapor lock. Vapor lock happens when the fuel in the lines gets way to hot and boils/vaporizes and causes stalling . Have the fuel lines wrapped in an insulated wrap or relocate them away from heat sources. Sometimes winter grade gasoline will cause this also.

Vapor lock can be caused by many different things, all coming down to the same root cause: too much heat in the fuel feed lines.

Low fuel pressure can cause the amount of heat needed to vapor lock to be lower than normal, so checking fuel pressure is important. Fuel pump going out feels a lot like vapor lock.

Engine overheat can also cause vapor lock. Clogged fuel filter can cause vapor lock. The fuel line should be routed away from the exhaust system.

You need a different mechanic. Vapor locks stopped in the 60's.

Help trouble locating vapor canister vent valve on 2006 Lincoln Navigator 5.4L

No vacuum lock on fuel injection
You have to diagnose the problem
with a sequence of proper testing
Check fuel pressure at the motor with a gauge
Check for injector pulse & spark when it fails to start

To promote easy starting, all gasolines contain volatile constituents that under some conditions, such as high ambient temperature, tend to produce more vapor than the fuel-system vents can handle. The action of an engine-mounted fuel pump, in decreasing the pressure at its inlet, tends to vaporize the fuel. If the vapor forms faster than the pump can draw it from the fuel line, the flow of fuel to a carburetor is effectively stopped and the engine stalls. Vapor lock is much less likely on a fuel-injected engine with an electric pump in the fuel tank. However, an engine with port fuel injection may experience vapor lock if the injector or fuel overheats, or if the Reid vapor pressure of the fuel is too high.

Read more: http://www.answers.com/topic/vapor-lock-1#ixzz2Pf13O7aL

Under the car from the fuel tank to vapor storage carbon canister near the fuel tank on a tray.

You can not have vapor lock on a fuel injected vehicle

The fuel either returns continually to the fuel tank
or is moving & sprayed thru the fuel injectors

Explain what the real issues are & what has been
done to correct

it must be leaking vapors out the cap. Is it a Ford cap or after market? You can't have ANY fuel vapor escaping through the filler pipe.