Boiling fuel
Thread Starter
6th Gear
Joined: Mar 2004
Posts: 6
Likes: 0
From: va beach va
Boiling fuel
I have a 81 c3 and i put an edelbrock eps intake and carb on now even with
a heat insilater gasket and insilated fuel lines the fuel boils in the carb and causes vapor lock I have tried averything from moving fuel lines to putting
electric pump on vapor lock still happens when I check the carb does not
seam real hot to the tuch
a heat insilater gasket and insilated fuel lines the fuel boils in the carb and causes vapor lock I have tried averything from moving fuel lines to putting
electric pump on vapor lock still happens when I check the carb does not
seam real hot to the tuch
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Boiling fuel (KENNYE81)
Are you running a fuel return line? Ive heard stories of how important the return line is on the vettes since they have high underhood temps. Sometimes when people do mods they delete the return line and wind up having vapor lock problems.
Can you describe the symptoms that lead you to believe that its vapor lock and not some other problem?
Can you describe the symptoms that lead you to believe that its vapor lock and not some other problem?
Thread Starter
6th Gear
Joined: Mar 2004
Posts: 6
Likes: 0
From: va beach va
Re: Boiling fuel (KENNYE81)
thanks people for your intrest i have no cat on car or headers .yes i did delete the return line. i am leaning to type of fuel like premeum having a
lower boiling point than regular. when i changed to regular it took longer
to start boiling back from carb into my clear fuel filter that is one foot away
from carb .
lower boiling point than regular. when i changed to regular it took longer
to start boiling back from carb into my clear fuel filter that is one foot away
from carb .
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Boiling fuel (KENNYE81)
You need the return line.
There is no difference in vapor pressure between regular and premium fuel, but there is a difference in vapor pressure depending on how much ethanol is added to the fuel in your area. Fuel with more ethanol has a lower boiling point.
There is no difference in vapor pressure between regular and premium fuel, but there is a difference in vapor pressure depending on how much ethanol is added to the fuel in your area. Fuel with more ethanol has a lower boiling point.
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Thread Starter
6th Gear
Joined: Mar 2004
Posts: 6
Likes: 0
From: va beach va
Re: Boiling fuel (KENNYE81)
i am running a in line electric fuel pump can't put a return line.
i also suspect the center head ports may be open and heating intake i am going to pull it and block it off.
i also suspect the center head ports may be open and heating intake i am going to pull it and block it off.
Tech Contributor
Joined: Aug 1999
Posts: 14,380
Likes: 6,390
From: At my Bar drinking and wrenching in Lafayette Colorado
Re: Boiling fuel (KENNYE81)
If you have an electric pump you absolutely have to run a return line: An electric pump will dead-head and and stall out, producing very low pressure if you don't have a return line to allow the fuel to continue to circulate. Failure to use a return line with an electric pump also results in pump overheating and rapid failure. Install a return line - mandatory with an electric pump.
Safety Car
Joined: Jun 2001
Posts: 4,004
Likes: 2
From: Severna Park Md
Re: Boiling fuel (KENNYE81)
You can run a return line. Theres at least two ways I know of. Theres at least two ways I know of. The more expensive way, which is adding a regulator block down line from the pump that has provisions for a return line. The cheap way, get a Mopar style inline filter and put it in between pump and carb. I switched to a hi po mechanical pump that did not have a fitting for the return. I just added the Mopar style filter to solve the problem. The Mopar filter has one fitting for the in line, and two, one smaller and on larger for the out side. The smaller fitting on the out side you use to connect to the return.
