STRANGE...UPDATE on Vapor Lock Issue

[JJRJR]

Hey guys,

Just off the phone with the mechanic. He said this is the strangest thing he's ever seen and he's been racing for many years. So, maybe you guys with more experience with this type of car can lay down some knowledge. LOL.

OK, I ordered the Purolator filter for use with the Inline Tube Stainless fuel return line. He got it all together with the new fuel return emptying into the nipple on the fuel tank, etc. He started it up again, let it sit with the hood closed and it STILL bubbles and fuel literally bubbles out of the car as soon as it gets hot.

SO, on a hunch, he put the original fuel filter back on and put a "T" fitting up by the carb on the black fuel line (he said there is a place to put a fuel pressure guage, so he used that spot). He ran a hose from that "T" fitting into the vapor return line, tied it all back together, started her and got her hot and the bubbles stopped. He said he's tried a few times today and it doesn't do it anymore and the engine keeps running.

It seems like the vapor and/or heat is minimal until it goes through the fuel pump. When vapor return connected before the fuel pump, we still got boiling/vapor. When connected after the pump, up by the carb, no more vapor/bubbles.

In addition, he moved the fuel feed line (mine is a thick blue rubber hose) that runs under the alternator, etc. and moved so it's further from heat sources. He said that that line/hose still gets pretty hot. He thinks it maybe Ethanol making the fuel hotter?

You guys have any thoughts on why this would happen? Why would vapor return fix problem if closest to the carb, but not when installed before the fuel filter?

I guess the good news is that he thinks it's fixed, but I'd sure like to know what the hell is happening.

Thanks gents,

John

 

[69hemibeep]

The separator or line should be beyond the pump towards the carb so he has it right As long as the return hole on the T isn't so large that the carbs starve at high RPMs

 

[JJRJR]

The separator or line should be beyond the pump towards the carb so he has it right

I'm keeping my fingers crossed, but isn't it true that the filter with the 3rd 1/4" outlet for the vapor would normally be installed before the pump? In place of where the OEM filter is?

 

[69hemibeep]

The separator or line should be beyond the pump towards the carb so he has it right

I'm keeping my fingers crossed, but isn't it true that the filter with the 3rd 1/4" outlet for the vapor would normally be installed before the pump? In place of where the OEM filter is?

Never put a filter ahead of a pump

 

[droptop]

The separator or line should be beyond the pump towards the carb so he has it right

I'm keeping my fingers crossed, but isn't it true that the filter with the 3rd 1/4" outlet for the vapor would normally be installed before the pump? In place of where the OEM filter is?

Never put a filter ahead of a pump

:yeathat:

 

[JJRJR]

I hear that, but I guess what he was saying is that when he put the vapor return type fuel filter in place of OEM, the gas still bubbled. When he moved the vapor return up by the carb, it stopped. First, does that make sense? Second, why the hell is my fuel bubbling??

 

[69hemibeep]

I hear that, but I guess what he was saying is that when he put the vapor return type fuel filter in place of OEM, the gas still bubbled. When he moved the vapor return up by the carb, it stopped. First, does that make sense? Second, why the hell is my fuel bubbling??

Heat

 

[JJRJR]

I hear that, but I guess what he was saying is that when he put the vapor return type fuel filter in place of OEM, the gas still bubbled. When he moved the vapor return up by the carb, it stopped. First, does that make sense? Second, why the hell is my fuel bubbling??

Heat

OK, so I learned some new information this morning. I had the same question with regard to the hole in the "T" messing with the fuel pressure, but he said it's very small and won't be an issue. We'll see.

I was thinking about what you said "never put a filter before a pump." So, I asked him and he said that the fuel filter was installed BEFORE the pump. First, why would you not do it and second do you think it has anything to do with the issue? I asked him to remove the filter ahead of pump and he's going to install another filter right after the pump.

On his GTX, he has a filter before and after the pump, but he has a racing motor with electric pump, fuel cell, NOS, the whole deal, so he said it's not the same. I'm curious if this could have been effecting performance all along. Clearly it seems it's why a little piece of rubber was in the carb a few weeks ago, it maybe came from the pump? Don't know.

As always, thanks for your help and input.

Best,

John

 

[69hemibeep]

He probably has the electric pump pushing fuel to the first filter which wouldn't be so bad. A filter ahead of the pump is a restriction and the pump has the ability to push fuel threw a filter especially a dirty one beyond it rather than to have a starved pump. Think about how far it pulls fuel from the tank with out an electric pusher at the tank. On my jeeps I split the return right before the carb. Here is a setup for a Hemi or 440-6 bbl. Steel line goes to rubber to the pump, rubber to the vapor separator or filter then to the carbs, you can see the two nipples at the bottom of the separator.

 

[JJRJR]

He probably has the electric pump pushing fuel to the first filter which wouldn't be so bad. A filter ahead of the pump is a restriction and the pump has the ability to push fuel threw a filter especially a dirty one beyond it rather than to have a starved pump. Think about how far it pulls fuel from the tank with out an electric pusher at the tank. On my jeeps I split the return right before the carb. Here is a setup for a Hemi or 440-6 bbl. Steel line goes to rubber to the pump, rubber to the vapor separator or filter then to the carbs, you can see the two nipples at the bottom of the separator.

Great, thanks. I was thinking the same thing. A filter ahead of the pump must be a restriction. The Eddy pump I have produces 6 PSI, so I agree if it has to pull all the way from the tank then through a filter before it starts pushing, must have been restrictive.

I asked him to do exactly as you have shown. I'm sure that will work. Thanks so much.

John

 

[zupanj]

If the filter was in front of the pump I wonder is the issue was cavitation rather thean heat?

 

[JJRJR]

I was thinking similarly. I've been reading that pumps don't like any restriction on the inlet side so maybe the extra work the pump had to do was making it hotter which makes the gas coming into the carb hotter.

I'm waiting to see how the mechanic did today on the work. Thanks for your help.

 

[69hemibeep]

If the filter was in front of the pump I wonder is the issue was cavitation rather thean heat?

Could be :yesnod:

 

[JJRJR]

OK Boys and Girls, just off the phone with mechanic. He put everything to OEM. Removed the fuel filter before the pump, installed the vapor return filter after the pump, return line off the 1/4" nipple into the fuel tank, 3/8" rubber hose from filter to carb. Then, he took another 3/4" rubber hose and wrapped the 3/8" rubber hose from filter to carb, then wrapped that in a reflective heat insulating material.

Let it run and run with hood closed and temp sits @ 190 degrees and car never missed a beat. He test drove her and he said she runs greast. SO, once again I must thank you guys for helping me out of another jam. Hopefully this fix continues to work, things tend to stop working when I'm about 5 miles from the shop.

Thanks again, let's keep our fingers crossed.

Best,

John

 

[69hemibeep]

OK Boys and Girls, just off the phone with mechanic. He put everything to OEM. Removed the fuel filter before the pump, installed the vapor return filter after the pump, return line off the 1/4" nipple into the fuel tank, 3/8" rubber hose from filter to carb. Then, he took another 3/4" rubber hose and wrapped the 3/8" rubber hose from filter to carb, then wrapped that in a reflective heat insulating material.

Let it run and run with hood closed and temp sits @ 190 degrees and car never missed a beat. He test drove her and he said she runs greast. SO, once again I must thank you guys for helping me out of another jam. Hopefully this fix continues to work, things tend to stop working when I'm about 5 miles from the shop.

Thanks again, let's keep our fingers crossed.

Best,

John

Just don't go more than 4.5 miles away :jester:

 

[cj69RR]

That should fix it up. If the filter was before the pump it will cavitat, the filter needs to be between the pump and garb. Good luck with it. When's the test drive?