Posted by Vaughn [172.68.143.63] on Friday, July 17, 2020 at 11:59:30 :
In Reply to: Lets talk about.. Vapor lock. posted by Jim Lee [162.158.106.87] on Friday, July 17, 2020 at 03:52:23 :
When the temperature gets hot out, during the vacuum phase of the pump, the boiling point, or vaporizing temperature of the fuel goes down, resulting in more vapors - thus vapor lock in some cases. Engine temperature plays a big role in this, the hotter the engine runs, the more heat under the hood, the more fuel will vaporize. Since you have replaced everything to the carb., and I assume the pump as well, I would look at these items:
- If the pump is NOS, how old is the pump? The diaphragm could be deteriorated from shelf life.
- How hot does the truck run? Is the thermostat 180 or 160? Temperatures will be down using a 160 thermostat.
- Do you have the pump heat shield on the exhaust manifold. This protects the pump from heat.
- Is the fuel line from the pump to the carb. always pointing up, no high points resulting in a downward feed?
- If you have an anti-vibration loop in the carb. line, is the loop on the bottom side of the line?
- Is the routing of the carb. fuel line in front of the exhaust manifold to facilitate cooling of the fuel by the fan - see link?
The more you can keep the temperature in the engine compartment down, the less likely you'll experience vapor lock.