Vapor Lock

DanBronco66
Aug 15, 2020

Rank III

Aug 15, 2020

Hello

I have a 1966 Ford bronco, over the last year I’ve been experiencing a vapor lock and I’ve tried a number of things to resolve it with no success. Installed a new fuel pump, we directed my fuel line, and a spacer under the carburetor.

I was hoping someone else would have some suggestions.Thanks and advance

Attachments

Last edited by a moderator: Aug 15, 2020

Bronco guy doing Bronco-ey things with his Bronco

Aug 15, 2020

#1
You should post some pics of your fuel line routing. Routing away from heat sources along with using non-ethanol fuel, placing heat reflecting (insulating) wrap around the fuel lines, removing the mechanical pump from the engine and using an inline pump away from the heat of the engine can all help. So can adding a regulator and returning fuel back to the tank so it stays cooler. You should also verify fuel pressure, as the higher the fuel pressure, the higher the boiling point.
First Edition 4dr
1967 Bronco
1993 Mustang Notchback
Deano Bronc

Bronco guy doing Bronco-ey things with his Bronco

Aug 15, 2020

#2
Depending upon what you are experiencing, you could have other issues with similar symptoms, such a leaky carburetor.
First Edition 4dr
1967 Bronco
1993 Mustang Notchback

Rank III

Aug 15, 2020

#3
You should post some pics of your fuel line routing. Routing away from heat sources along with using non-ethanol fuel, placing heat reflecting (insulating) wrap around the fuel lines, removing the mechanical pump from the engine and using an inline pump away from the heat of the engine can all help. So can adding a regulator and returning fuel back to the tank so it stays cooler. You should also verify fuel pressure, as the higher the fuel pressure, the higher the boiling point.


Thanks - attached is a short video

Bronco guy doing Bronco-ey things with his Bronco

Aug 15, 2020

#4
Thanks - attached is a short video
Must not be able to see it on the mobil version, or you forgot to add the video.
First Edition 4dr
1967 Bronco
1993 Mustang Notchback

Rank IV

Aug 16, 2020

#5
I don't think the forum allows video upload, I tried to use a gif earlier and it would not recognize the video file

Bronco guy doing Bronco-ey things with his Bronco

Aug 16, 2020

#6
That’s right. I tried to upload some Bronco action on Chinaman Gulch and it wouldn’t let me upload.
First Edition 4dr
1967 Bronco
1993 Mustang Notchback

Rank VI

Aug 16, 2020

#7
Upload via youtube and link it, assuming BN allows
Build week of 7/26....still....no its 8/16 now

Bronco guy doing Bronco-ey things with his Bronco

Aug 16, 2020

#8
Or just post up a couple of pictures. I like to look to see how the coolant lines are routed, how close to the engine the fuel line is and such. Also, note the fuel line routing to the rear. I was working on a GT500 (clone) that had the fuel lines rerouted and placed above the exhaust nearly all the way from the axle to the engine. Relocating the lines back to the factory location took care of that vapor lock issue.
First Edition 4dr
1967 Bronco
1993 Mustang Notchback

Rank III

Moderator

Moab or bust!!!

Aug 16, 2020

#10
IMG_4863.mov
How long after you drive it does it start having issues?
2022 Bronco Badlands, 4D, Hot Pepper Red, 2.7, Squatch, Lux, and MIC.
7/13/2020 10:04pm reservation. Blend 6/16/2022 Delivered 6/26/2022.
Dealership - Stephen's Auto Center.

Rank III

Aug 16, 2020

#11
Thanks - attached is a short video
IMG_4863.mov
How long after you drive it does it start having issues?

30 minutes - like clock work - I’m working on downloading a video -

Rank III

Aug 16, 2020

#12

Bronco guy doing Bronco-ey things with his Bronco

Aug 16, 2020

#13
One thing I notice is fuel filter location. While I see lots of cars with these without problems, filters on the inlet side of the pump can create restrictions which create vacuum, which in turn can cause vapor-lock due to the lower boiling point of the fuel when it arrives at the fuel pump. I would start by adding some insulating sleeve on the fuel line from pump to carb and relocate the filter to the pressure side after the pump.
First Edition 4dr
1967 Bronco
1993 Mustang Notchback

Rank III

Aug 16, 2020

#14
Thanks
One thing I notice is fuel filter location. While I see lots of cars with these without problems, filters on the inlet side of the pump can create restrictions which create vacuum, which in turn can cause vapor-lock due to the lower boiling point of the fuel when it arrives at the fuel pump. I would start by adding some insulating sleeve on the fuel line from pump to carb and relocate the filter to the pressure side after the pump.

Rank III

Aug 16, 2020

#15
Thanks for the quick response - I’ll make those adjustments - I was thinking of replacing the tank since it is original fuel tank. I was also going to move a high end fuel pump as well.

thanks again for you comments

Rank V

Aug 18, 2020

#16
Have you changed the gas cap lately, its a long shot. What happens when you vent the cap.
Dave

Rank III

Aug 18, 2020

#17
Have you changed the gas cap lately, its a long shot. What happens when you vent the cap.

Thanks for the response - yes
- that was one of the first things I did..

Thanks
Mantruck
Moderator

Rank III

Aug 19, 2020

#18
If you think it’s that metal line, why not try a rubber hose between to fuel pump and carb and see if it cures the problem. If it does then you can take your time are replace the metal line.
Has the metal line been on there for a while? What changed to creat the problem?

Rank III

Aug 19, 2020

#19
The strange things is nothing changes that I can put my finger on. A few years ago I put a new carb on but it ran great for two years before this started. When this started I replaced the fuel pump, thinking the old one was very old.... I got it thru one of the Bronco sites that I get my parts. It was just a standard fuel pump. I also started running leaded gas in the Bronco Vs unleaded gas.
The metal fuel line been on for years. I was thinking of replacing it with high end fuel line.

The fuel line from the tank Has a fuel filter (clear filter) before the fuel pump, when the vapor lock Happens there is no fuel in the fuel filter. 20 to 30 minutes later you can see fuel in the filter - crazy

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