Engine cut out dilemma


IHC in the early to mid-fifties.

Yard Art
Yard Art

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Location: Logansport, Indiana

Post Wed Sep 14, 2022 8:53 am

Engine cut out dilemma

Whilst careening down the highway at tremendous speeds (prolly 50-55), my L110 motor began to putter in and out. Once I let off of the accelerator, it became more predictable at running smoothly again. I’ve tried this several times with the same result. It’s fine at speeds below 40 (estimated). Initially, I was convinced it was the fuel pump’s inability to produce enough go go juice, but not sure. Any suggestions or solutions before I start replacing/rebuilding parts?

Golden Jubilee
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Post Wed Sep 14, 2022 12:41 pm

Re: Engine cut out dilemma

At the "tremendous speeds" Thats what I would do.

Golden Jubilee
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Post Wed Sep 14, 2022 5:15 pm

Re: Engine cut out dilemma

I am going to take the chance of being disagreed with and suggest your engine is suffering fuel starvation.
I do not like the OEM mechanical fuel pumps and I have changed them out for electric. I like to have a residual pressure/check valve system with a fuel return line to the fuel tank.
This system allows an oversupply of fuel to return to the tank. This keeps the fuel in partial circulation and the fuel does not slow in the fuel line and get hot. The heating of modern fuel happens at a lower temperature than the gasoline of way-back-then. When the gasoline gets hot, it can cause vapor-lock.
The electric fuel pump should be mounted close to the fuel tank. This will make the pick-up tube length shorter. Fuel is better pushed, after the electric pump. If there is a little pressure in the fuel line after the electric pump, this can help reduce vapor-lock.
https://www.walmart.ca/en/ip/HTRACING-A ... ABJ4LU3BXG
IHC ran the fuel line around and close to the engine block. This is a bad design that easily heats the fuel to a vapor.
I will try and post a picture of the residual pressure/check valve with boost reference, I installed on my supercharged Ford.
Attachments
FUEL GAUGE TOP VIEW.jpg
Very complicated.
BOOST REFERENCED FUEL PRESSURE VALVE.jpg
Residual check valve
I would rather have tools I do not need than to need tools I do not have
Thinking risks being controversial and possibly being offensive

Yard Art
Yard Art

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Location: Logansport, Indiana

Post Thu Sep 15, 2022 6:55 am

Re: Engine cut out dilemma

I’ll check into the electric fuel pump option…hadn’t considered it to this point. Thx!

Pile of Parts
Pile of Parts

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Location: Singers Glen, VA

Post Fri Sep 16, 2022 7:30 am

Re: Engine cut out dilemma

I have a fuel pressure gauge like this one:
https://www.lislecorp.com/specialty-too ... ump-tester

I would plumb it into the fuel feed line into the carburetor and zip-tie the gauge to the windshield wiper. Take it for a drive and note any pressure loss when you get up to speed. Be sure there's not a clogged filter or kinked line causing fuel starvation. It's possible the fuel tank vent is not keeping up, although I'm not sure it would recover that quickly when you slow down.

Most importantly you need good data for a diagnosis. Mount your gauge and let us know what you find.

Yard Art
Yard Art

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Location: Logansport, Indiana

Post Sat Sep 17, 2022 6:34 am

Re: Engine cut out dilemma

Good idea, I’ll see what happens and let ya know


bossybinder wrote:I have a fuel pressure gauge like this one:
https://www.lislecorp.com/specialty-too ... ump-tester

I would plumb it into the fuel feed line into the carburetor and zip-tie the gauge to the windshield wiper. Take it for a drive and note any pressure loss when you get up to speed. Be sure there's not a clogged filter or kinked line causing fuel starvation. It's possible the fuel tank vent is not keeping up, although I'm not sure it would recover that quickly when you slow down.

Most importantly you need good data for a diagnosis. Mount your gauge and let us know what you find.
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Golden Jubilee
Golden Jubilee

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Post Sat Sep 17, 2022 1:59 pm

Re: Engine cut out dilemma

Your issue does not sound like a VP problem
and the suggestions above sound like a good direction to check out but,

The heating of modern fuel happens at a lower temperature than the gasoline of way-back-then. When the gasoline gets hot, it can cause vapor-lock.



I use to have an occasional issue with vapor-lock ..

My quick fix solved the problem, I wrapped the fuel line with glass heat tape
above the exhaust manifold .. worked for me..
Image

Be safe - sm
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Golden Jubilee
Golden Jubilee

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Location: Plano, TX

Post Fri Sep 23, 2022 4:02 pm

Re: Engine cut out dilemma

how full is your fuel tank? could be having a problem with pick up too if it is close to running empty and higher speeds causing sloshing? Just a thought. Certain just sounds like a fuel delivery issue.

Yard Art
Yard Art

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Joined: Mon Jul 25, 2016 9:27 am

Location: Logansport, Indiana

Post Sun Oct 02, 2022 12:36 pm

Re: Engine cut out dilemma

With other projects in the mix, I haven't had time to address the issue. I did drive it once since and it is now cutting out at lower speeds. I’ll get to it soon I hope.

Golden Jubilee
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Post Sun Oct 02, 2022 1:44 pm

Re: Engine cut out dilemma

You can rule out Ign as the problem as it would have blown off the exh by this point if it was cutting out at speed.
So that leave fuel. I have seen old steel line that will allow air in without leaving a tell tail drip on the ground.
Mechanical fuel pumps are sized to deliver more than enough fuel at full throttle low speed, so it isn't a design defect. It could be the fuel line, a bad stand pipe in the tank if used, or clogging of filter or passages in the carb. None of those problems will solved by an electric, but it might "mask" a bad fuel line or standpipe.
A partially plugged exh can cause a loss of power but not a complete "cut-out" that returns at lower throttle settings.
Look for a leak around the fuel pump, and gas in the oil for a defective fuel pump. Some less likely causes could be a worn fuel pump eccentric on the cam,
I think a bad fuel line or standpipe in the tank are the most likely cause. A fuel pressure reading would confirm.
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