vapor lock issue
10-29-2010, 09:10 PM
#1
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vapor lock issue my wife drove my truck and ran out of gas. she pumped pedal several times before she realized it had no fuel. now i cant get it to start after putting fuel in tank and carb. Y??? is it vapor locked????? if so how do i fix the problem.??? got into engine compartment and did see fuel spraying into carb when i moved the throttle body? is there any quick fixes for this issue????
thank you
thank you
11-08-2010, 11:33 AM
#2
first, it is not vapor lock. the definition of vapor lock, at least in my opinion, is when liquid gasoline in the fuel line turns gaseous from heat given off from the engine. when this happens, the vapor when it gets into the carb will escape out the bowl vent and not make it into the engine. The engine will lean out and stall.
All you have to do is let the engine (fuel line) cool, and it fixes itself.
What is largely said is the fuel pump can't pump vapor, which is not true. If it's a mechanical diaphram pump, they will pump vapor, air, and just about anything, what happens really is you get a loss of fuel to the carb, it leans out and stalls.
Vapor lock is only associated with low pressure fuel systems, such as a carburated setup where fuel pressure is less than 10psi. Fuel injection having pressures > 30psi will never experience "vapor lock" because they are under pressure. And vapor lock only happens when fuel pressure is really low, if it's over 2psi that can be enough to keep the fuel liquid in the line.
Easiest way to know is by working the throttle on the carb and stroking the accelerator pump, if no fuel squirts then there is no liquid fuel in the carb. If you have the electric pump running then still don't get fuel you have a priming problem, possibly from vapor lock. If it's vapor lock it would be unbearably hot leaning over the engine.
And if you dump gas down the carb, like 1-4 ounces worth, crank the engine and it doesn't fire and run for a few seconds, especially a warm engine, then it's not a fuel problem, you most likely have ignition problems.
All you have to do is let the engine (fuel line) cool, and it fixes itself.
What is largely said is the fuel pump can't pump vapor, which is not true. If it's a mechanical diaphram pump, they will pump vapor, air, and just about anything, what happens really is you get a loss of fuel to the carb, it leans out and stalls.
Vapor lock is only associated with low pressure fuel systems, such as a carburated setup where fuel pressure is less than 10psi. Fuel injection having pressures > 30psi will never experience "vapor lock" because they are under pressure. And vapor lock only happens when fuel pressure is really low, if it's over 2psi that can be enough to keep the fuel liquid in the line.
Easiest way to know is by working the throttle on the carb and stroking the accelerator pump, if no fuel squirts then there is no liquid fuel in the carb. If you have the electric pump running then still don't get fuel you have a priming problem, possibly from vapor lock. If it's vapor lock it would be unbearably hot leaning over the engine.
And if you dump gas down the carb, like 1-4 ounces worth, crank the engine and it doesn't fire and run for a few seconds, especially a warm engine, then it's not a fuel problem, you most likely have ignition problems.
