Verajet heat soak?!?!?

[LilRobert1367]

Hey guys,I am having an issue with my truck which I'm thinking it's heat soak. I drive a 1979 c20 250 with a Verajet carb. It doesn't happen all the time but some time I will drive it for 10 mins or so park it go in the store and wheni get back in the truck it will be hard to start. Also I will notice even after I drive it around I will smell gas. All of the fuel system is new as well except the charcoal canister. Before I restored the truck it ran just on propane but I converted it back to gas. Thank for the help in advance!

 

[AuroraGirl]

Hey guys,I am having an issue with my truck which I'm thinking it's heat soak. I drive a 1979 c20 250 with a Verajet carb. It doesn't happen all the time but some time I will drive it for 10 mins or so park it go in the store and wheni get back in the truck it will be hard to start. Also I will notice even after I drive it around I will smell gas. All of the fuel system is new as well except the charcoal canister. Before I restored the truck it ran just on propane but I converted it back to gas. Thank for the help in advance!

is there 3 ports on the fuel pump or only 2 ?

 

[Copymutt]

After a drive to warm it up, pull the air cleaner, slowly open the throttle while using a flashlight/ phone to see down the venturis. Keep the throttle open . If you see raw gas dribbling down the venturi your float is either set too high or fuel is boiling or both. A plastic cutting board as a carb insulator will drastically lower the carb temperature. Careful to check hood clearance.

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[LilRobert1367]

is there 3 ports on the fuel pump or only 2 ?

It's a 2 port fuel pump.

 

[LilRobert1367]

After a drive to warm it up, pull the air cleaner, slowly open the throttle while using a flashlight/ phone to see down the venturis. Keep the throttle open . If you see raw gas dribbling down the venturi your float is either set too high or fuel is boiling or both. A plastic cutting board as a carb insulator will drastically lower the carb temperature. Careful to check hood clearance.

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Thanks for the information. I will trying this out.

 

[LilRobert1367]

After a drive to warm it up, pull the air cleaner, slowly open the throttle while using a flashlight/ phone to see down the venturis. Keep the throttle open . If you see raw gas dribbling down the venturi your float is either set too high or fuel is boiling or both. A plastic cutting board as a carb insulator will drastically lower the carb temperature. Careful to check hood clearance.

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I did what you said. I dont see fuel dribbling down the venturi but did hear the fuelboil when I open the throttle and there was like a cloudy fog just sitting in the venturi.

 

[Copymutt]

You can double confirm by laying a bag of ice on the intake around the carb. If you don't hear the boil then go for a spacer.

 

[LilRobert1367]

You can double confirm by laying a bag of ice on the intake around the carb. If you don't hear the boil then go for a spacer.

Yeah I don't think I need to test with the ice. The touched the carb and there was some significant heat coming off it.

 

[AuroraGirl]

convert to a three port fuel pump, if you install a new fuel tank sender for having a third port , then the fuel pump, just run a line to enable this. if you didnt want to change fuel pump you could run a external fuel filter with 3 connections on it that would hook up to your pipe connecting to the fuel tank sender. These two things will greatly assist fighting the problem. A phenolic spacer , a heat shield for lines or insulated lines that run to the carb and ensuring any fuel line from the tank to the fuel pump isnt near exhaust or has a heat shield also helps.

Finally, if you were to install a small flow-through fuel pump in the fuel feed near the tank that is ran on a timer or a similar setup for just a few moments before attempting to start, it will also help a lot.

Basically the fuel is getting too hot near the carb (thats what the three port pump/filter/tank sender fixes) and the fact that gasoline is pulled under a vacuum to the engine, the gasoline by its nature is already prone to turn into vapor at said temps and how its formulated these days, droppign the pressure in the line causes fuel pump to pump vapor (which is does very poorly)
So thats what the fuel pump in the feed pipe near the tank solves, it pressurizes the line which has the effect of forcing vapor back into a liquid and thus letting your fuel pump do its thing.
THe pump would have to allow flow through it , it couldnt be a check valve kind. and be manually run by switch or get creative and find a way to run it on a short timer

 

[Ricko1966]

convert to a three port fuel pump, if you install a new fuel tank sender for having a third port , then the fuel pump, just run a line to enable this. if you didnt want to change fuel pump you could run a external fuel filter with 3 connections on it that would hook up to your pipe connecting to the fuel tank sender. These two things will greatly assist fighting the problem. A phenolic spacer , a heat shield for lines or insulated lines that run to the carb and ensuring any fuel line from the tank to the fuel pump isnt near exhaust or has a heat shield also helps.

Finally, if you were to install a small flow-through fuel pump in the fuel feed near the tank that is ran on a timer or a similar setup for just a few moments before attempting to start, it will also help a lot.

Basically the fuel is getting too hot near the carb (thats what the three port pump/filter/tank sender fixes) and the fact that gasoline is pulled under a vacuum to the engine, the gasoline by its nature is already prone to turn into vapor at said temps and how its formulated these days, droppign the pressure in the line causes fuel pump to pump vapor (which is does very poorly)
So thats what the fuel pump in the feed pipe near the tank solves, it pressurizes the line which has the effect of forcing vapor back into a liquid and thus letting your fuel pump do its thing.
THe pump would have to allow flow through it , it couldnt be a check valve kind. and be manually run by switch or get creative and find a way to run it on a short timer

Just trigger it off the r terminal on the starter while the starter is engaged the transfer pump would run it would only take a few seconds to push liquid fuel to the main pump. Liquid under pressure raises the boiling point,liquid under vacuum lowers the boiling point,that is the reason we use pressurized cooling systems. And it's the reason we pull vacuum on air conditioning before charging,the vacuum boils the water out of the system. The way the return style pump or filter works is the fuel is constantly moving instead of deadheading at the carb. The cool fuel from the tank is constantly being pumped through the lines the hot fuel in the lines is forced back into the tank to cool. If you go with a 3 line filter the outlets should be pointing straight up.

 

[AuroraGirl]

Just trigger it off the r terminal on the starter while the starter is engaged the transfer pump would run it would only take a few seconds to push liquid fuel to the main pump. Liquid under pressure raises the boiling point,liquid under vacuum lowers the boiling point,that is the reason we use pressurized cooling systems. And it's the reason we pull vacuum on air conditioning before charging,the vacuum boils the water out of the system. The way the return style pump or filter works is the fuel is constantly moving instead of deadheading at the carb. The cool fuel from the tank is constantly being pumped through the lines the hot fuel in the lines is forced back into the tank to cool. If you go with a 3 line filter the outlets should be pointing straight up.

also its not trying to shove more fuel at the carb than it can use, thats just needlessly pushing and adding heat

 

[Ricko1966]

also its not trying to shove more fuel at the carb than it can use, thats just needlessly pushing and adding heat

That would be Dead heading.