Vapor Lock

[connapp]

What success has anyone has with correcting Vapor Lock on a 4.3 carbureted engine

 

[Bondo]

What success has anyone has with correcting Vapor Lock on a 4.3 carbureted engine

Ayuh,...... Welcome Aboard,...... What sorta diagnosis have you done to come to this conclusion,..??

 

[alldodge]

What success has anyone has with correcting Vapor Lock on a 4.3 carbureted engine

Ayuh,...... Welcome Aboard,...... What sorta diagnosis have you done to come to this conclusion,..??

Agree, VL is not magic that just happens

 

[Scott Danforth]

I doubt that a carbureted 4.3 has vapor lock

What symptoms are you experiencing. Is this a new to you boat with this issue, or a boat you owned for a while that recently developed symptoms

 

[Lou C]

Vapor lock occurs when the fuel in the carb bowl gets so hot it boils and then it doesn't atomize well. In the old days we used carb insulators and insulated fuel lines going over hot parts of the engine. On Pre-Votec engines there is an exhaust crossover in the intake that heats the area under the carb to prevent carb icing (automotive applications), the gaskets have a restrictor in them to keep it from passing too much heat, if those aren't installed, it could conceivably happen, but this is only on pre-1995 engines, Vortec intakes do not have an exhaust crossover.
How did you determine you have vapor lock?
My old 4.3 has a Quadrajet with the typical thick gasket, never had vapor lock in all the years I have owned it. I did install those restrictors in the intake gaskets when I had the top end of the engine apart.

 

[connapp]

Ayuh,...... Welcome Aboard,...... What sorta diagnosis have you done to come to this conclusion,..??

Starts fine when cold, starts fine while we are skiing and tubing, then we stop for an hour or so to swim, starts up but goes a few hundred feet and dies then hard to start

 

[connapp]

I doubt that a carbureted 4.3 has vapor lock

What symptoms are you experiencing. Is this a new to you boat with this issue, or a boat you owned for a while that recently developed symptoms

Starts fine when cold and while we ski and tube then we stop for an hour or so, then starts up goes a couple hundred yards and dies

 

[connapp]

Vapor lock occurs when the fuel in the carb bowl gets so hot it boils and then it doesn't atomize well. In the old days we used carb insulators and insulated fuel lines going over hot parts of the engine. On Pre-Votec engines there is an exhaust crossover in the intake that heats the area under the carb to prevent carb icing (automotive applications), the gaskets have a restrictor in them to keep it from passing too much heat, if those aren't installed, it could conceivably happen, but this is only on pre-1995 engines, Vortec intakes do not have an exhaust crossover.
How did you determine you have vapor lock?
My old 4.3 has a Quadrajet with the typical thick gasket, never had vapor lock in all the years I have owned it. I did install those restrictors in the intake gaskets when I had the top end of the engine apart.

Starts fine when cold and while skiing and tubing, stop for an hour or so then starts goes a few hundred feet and dies.

 

[Lou C]

Another cause if that could be a bad ignition coil breaking down with heat. Not common but it can happen.

 

[Scott Danforth]

When it dies, verify you have spark.

Does your ignition trigger have 2 wires, or 3 wires? If 2 wires, it may be a bad trigger.

Go thru the TV ignition troubleshooting tree in the stickies

 

[connapp]

Another cause if that could be a bad ignition coil breaking down with heat. Not common but it can happen.

Yes, already did that, it helped but occasionally still does it