need help possible vapor lock

[dan73]

I've read all I can find about this so here is my problem. no trouble as long as I stay under 2500 rpm. when I push it over 2700+ rpm at highway speeds it acts like it runs out fuel. 302 - 2bl motorcraft, elect. carter pump. I moved the exhaust to the passenger side. (BC's). no change. If I set at a red light for any length of time, after I take off and shift it does the same thing too. Never gets over 180 degrees even at idol Any ideas?

 

[Skiddy]

do you have that spacer that is under the carb, also where is your pump located it may just be getting hot

 

[Deano]

Check the vent lines coming out of the tank. It mite be stopped up causing vaperlock. Just a thought.

 

[dan73]

yes the alum. spacer is there. I have had the pump every damn where you can think of, no change

 

[dan73]

Check the vent lines coming out of the tank. It mite be stopped up causing vaperlock. Just a thought.

ok, havent tried that but i have ran without the gas cap

 

[dan73]

also i always smell gas right before it does it

 

[Justafordguy]

Can you tell where the smell is coming from? Tank end or carb end?

 

[dan73]

Can you tell where the smell is coming from? Tank end or carb end?

think its from the vapor tank behind drivers seat

 

[Rustytruck]

Change the fuel filter and go over all the fuel lines before the fuel pump you may be sucking air in to the lines. Check the tank selector valve may have to remove the cap and replace the o-ring inside.

 

[dan73]

Change the fuel filter and go over all the fuel lines before the fuel pump you may be sucking air in to the lines. Check the tank selector valve may have to remove the cap and replace the o-ring inside.

changing every line on it tonight. Would the valve suck air without leaking? fuel filter and tank socks are new, tanks are clean

 

[Skiddy]

changing every line on it tonight. Would the valve suck air without leaking? fuel filter and tank socks are new, tanks are clean

my brothers truck would do that a lot finally we bypassed the valve and fixed it. it was pulling air into it and was not leaking. did take us a while to finally find out what it was.

 

[69for5]

This is going to sound crazy......at least I thought it did. I was BSin with a fire mechanic about general wrenching and vapor lock came up. His dad (old army wrench) gave him a trick for the toolbox years back. He was driving an old postal jeep back from camping one day and ran into vapor lock issues. He called his dad for advice and he gets "get some wooden clothes line clips and stick em on the fuel line. It will take away some heat and cure your problem. My first thought was WTF??? long story short, he did it and it worked........just Damn right odd

 

[Skiddy]

This is going to sound crazy......at least I thought it did. I was BSin with a fire mechanic about general wrenching and vapor lock came up. His dad (old army wrench) gave him a trick for the toolbox years back. He was driving an old postal jeep back from camping one day and ran into vapor lock issues. He called his dad for advice and he gets "get some wooden clothes line clips and stick em on the fuel line. It will take away some heat and cure your problem. My first thought was WTF??? long story short, he did it and it worked........just Damn right odd

I have actually heard of doing that before, just never tried it. maybe i am crazy as well;D

 

[Rustytruck]

If you are using the stock fuel fuel pump at the engine the pump is sucking fuel in if its easier to suck in air than fuel then you get air. Make sure your tank vents are clear. Might try driving the truck with the gas cap off and see if your problem goes away. inproper venting could cause you to suck air in a marginal system or create enough vacuum that the pump cant pump fuel.

 

[NYLES]

Whats timing set at?

And what psi is the pump providing?

 

[blubuckaroo]

Vapor lock happens when the fuel in the suction line gets hot enough to boil. The pump can't pump vapors. Electric pumps are usually imune to it unless the pump is under the hood. I'd look for a restriction, or bad pump.

 

[Wyflyer]

Here is some good info about vapor locking. But the only way to keep the lines cool enough to prevent the fuel from changing phases in the fuel line; IE, "boiling" or "vaporizing" or changing from liquid to vapor in the line.
Does it have dual exhausts with exhaust piping near the fuel lines or tank? This is one reason many vehicles have the fuel lines go up the driver's side, single exhaust and muffler on the passenger side.
I once had a 96 Bronco with the same problem, the only way it would run on hot days is to keep it full of fuel so it wouldn't slosh around and make vapors, or to cool the tank down with a garden hose.
I think a device could be built to act as a sort of expansion tank, with a vapor line returning to the tank, but it would require an in tank pump. And EFI does the exact same thing anyhow.

http://en.wikipedia.org/wiki/Gasoline#Volatility

 

[dan73]

This is going to sound crazy......at least I thought it did. I was BSin with a fire mechanic about general wrenching and vapor lock came up. His dad (old army wrench) gave him a trick for the toolbox years back. He was driving an old postal jeep back from camping one day and ran into vapor lock issues. He called his dad for advice and he gets "get some wooden clothes line clips and stick em on the fuel line. It will take away some heat and cure your problem. My first thought was WTF??? long story short, he did it and it worked........just Damn right odd

tried that already

 

[dan73]

Here is some good info about vapor locking. But the only way to keep the lines cool enough to prevent the fuel from changing phases in the fuel line; IE, "boiling" or "vaporizing" or changing from liquid to vapor in the line.
Does it have dual exhausts with exhaust piping near the fuel lines or tank? This is one reason many vehicles have the fuel lines go up the driver's side, single exhaust and muffler on the passenger side.
I once had a 96 Bronco with the same problem, the only way it would run on hot days is to keep it full of fuel so it wouldn't slosh around and make vapors, or to cool the tank down with a garden hose.
I think a device could be built to act as a sort of expansion tank, with a vapor line returning to the tank, but it would require an in tank pump. And EFI does the exact same thing anyhow.

http://en.wikipedia.org/wiki/Gasoline#Volatility

exhaust is on pass. side.

 

[dan73]

Ok, changed the lines and hoses. Still does it. Noticed something new this time. Happened out in the middle of nowhere where it was quiet. When I pulled over I could hear fuel bubling in the vapor tank. I set there about a minute when it stopped bubbling I turned the pump on. No fuel, ( I can tell by the sound of the pump) I get out take the gas cap off, instantly picks up fuel, I jump in it fires up. But It still has done this with the cap off?????