What exactly is vapour lock ?
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From: NORWICH UNITED KINGDOM
What exactly is vapour lock ?
What is it and have I got it ? My car runs fine until it gets hot and i want to accelerate after it has been idling for a few seconds. When I put my foot down it splutters and faulters like theres no fuel then it picks up. Its definately not electrics I have checked and replaced most items. It also does not do this every time. I did have a problem before on the carb being too lean on idle and now this is fixed.
Instructor
Joined: Jan 2005
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From: Waterford MI
I had a similar issue with mine where it would (idling in a parking lot) on a hot day, just slowly sputter away and stall.
The diagnosis was the engine compartment was hot and vaporizing the fuel before it got to the carb.
Did a radiator overhaul and installed an electric fuel pump (possibly overkill) and it runs fine in 100 degrees.
The diagnosis was the engine compartment was hot and vaporizing the fuel before it got to the carb.
Did a radiator overhaul and installed an electric fuel pump (possibly overkill) and it runs fine in 100 degrees.
Pro
Joined: Jan 2006
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vapor lock is a condition where fuel vaporizes in the lines, resulting in little flow to the carburetor or fuel injection unit. very common with tightly packed steel fuel lines. it makes taxiing our airplanes a real bitch in the summer.
Melting Slicks
Joined: Feb 2001
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From: TEXAS - you mean there are other states?
Is there any insulation or different type line to use? I assume stainless has the same conductivity and makes no difference?
Also - I thought vapor lock ocurred in the combustion chamber and was a cause that prevented the motor from turning over.
Also - I thought vapor lock ocurred in the combustion chamber and was a cause that prevented the motor from turning over.
Safety Car
Joined: Aug 2000
Posts: 3,711
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From: San Antonio TX
You're thinking of a hydraulic.
You can lessen the effects of high fuel heat in the line by insulating it. You can use ordinary hardware store pipe insulation. Though, most of the time, if the fuel is boiling in the line, your fuel pump isn't delivering adequate pressure or volume. You may also be boiling the fuel in the bowl due to a missing insulator gasket or the wrong carb gasket, depending on the type of intake you're using. You may also have problems with a sticking heat riser, which is the usual suspect for this kind of behavior.
You can lessen the effects of high fuel heat in the line by insulating it. You can use ordinary hardware store pipe insulation. Though, most of the time, if the fuel is boiling in the line, your fuel pump isn't delivering adequate pressure or volume. You may also be boiling the fuel in the bowl due to a missing insulator gasket or the wrong carb gasket, depending on the type of intake you're using. You may also have problems with a sticking heat riser, which is the usual suspect for this kind of behavior.
Pro
Joined: Jan 2006
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Originally Posted by kaiserbud
Is there any insulation or different type line to use? I assume stainless has the same conductivity and makes no difference?
Also - I thought vapor lock ocurred in the combustion chamber and was a cause that prevented the motor from turning over.
Also - I thought vapor lock ocurred in the combustion chamber and was a cause that prevented the motor from turning over.
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Joined: May 2006
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From: NORWICH UNITED KINGDOM
I got an ebelbrook carb and maniflold. The carb has the spacer in place. The fuel lines from the pump are all rubber. The fuel filter is in the line between the pump and carb and is new. I have noticed that when you turn off engine the fuel will flow back down the pipes to the pump. I know this because the fuel filter is see through. Maybe this is a problem. Although when you crank it the fuel comes straight back. The engine never overheats that I know of.
Race Director
Joined: May 2006
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From: Dayton, Ohio
Your problem is most likely the metal line before the pump-it picks up the heat from the exhaust while it is sitting there in the line-when your "driving" the fuel is moving past that high heat spot and not picking up that high heat-in later years they put on a return line and the fuel is constantly moving past that high heat point instead of sitting there trying to boil-this return line helped with vapor lock but dont think it was the primary reason.Remove that hold down bolt and slide on some insulation and it will help-being against the hot frame adds to it.
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Melting Slicks
Joined: May 1999
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From: Moon Township PA
It has always been my understanding that vapor lock is when the fuel in the supply line vaporizes before it hits the carb, due to heat absorption. I thought this usually happens when the car has been shut down and the heat is allowed to soak into the fuel line.
Your problem sounds more like the accelerator pump in your carb needs to be adjusted.
Gary
Your problem sounds more like the accelerator pump in your carb needs to be adjusted.
Gary
Burning Brakes
Joined: Jun 2006
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From: San Angelo TX
Originally Posted by 5day
What is it and have I got it ? My car runs fine until it gets hot and i want to accelerate after it has been idling for a few seconds. When I put my foot down it splutters and faulters like theres no fuel then it picks up. Its definately not electrics I have checked and replaced most items. It also does not do this every time. I did have a problem before on the carb being too lean on idle and now this is fixed.
In a car with no modifications, the mostly likely cause of vapor lock is a weak fuel pump.
But, the symptoms you descibe could be that the accelerator pump in the carb is not working right.
Last edited by roger55; Jul 23, 2006 at 08:59 AM.
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From: NORWICH UNITED KINGDOM
I see. yes sorry I put stock in profile when i got the car. I didnt reallise the extra bits where not stock untill i looked close at it and read details about my car on this site. I should change profile. I seem to have 2 fuel lines along the chassis in the engine bay. One is slightly thicker than the other so i am guessing I got the newer fual line version. I am now thinking it is the gasket between the manifold and the carb. It looks a bit thin to be an insulation one. I WILL attached a photo of it as soon as i can work out how to do it. Again this problem only happens when hot. Oh and by the way I think I have an extra large radiator installed. It appears that the mount on one side is not located correctly as its wider than it would normally be. That might be the reason she does not overheat on the temp gauge but the engine bay still is very hot.
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From: NORWICH UNITED KINGDOM
Thread Starter
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Joined: May 2006
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From: NORWICH UNITED KINGDOM
Roger55 and Garys I think you guys are right. I just adjusted the setting on the pump. I was in middle hole. Top hole made it worse, buttom hole is very smooth no stumble. Thanks.