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  #1   IP: 108.51.19.207
Old 06-08-2021, 01:24 AM
svsonora svsonora is offline
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Engine only running on choke - Kinking fuel line from fuel pump to carb

My boat developed this problem where the engine would only run with the choke open. The carb had been cleaned recently, fuel in the engine looks good, and my fuel pump is pumping fine. I think I traced the problem to a kinked fuel line.

I replaced the copper line with 1/4 tubing, and after a few weeks, it developed a kink. I put a hose clamp on the kink to keep it open, but its still kinked and I don't think enough fuel is getting to the carbs.

A part of me thinks this doesn't make sense -- if the carb isn't getting enough fuel, why would it matter if the choke is open or not? Could the lack of pressure from the reduced fuel flow be causing this?

Any elegant solutions? I'm thinking about buying a molded fuel line for the 180 degree bend, but I'm going to try sliding a bigger section of fuel line over it to prevent the kink.
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  #2   IP: 47.142.140.156
Old 06-08-2021, 02:45 AM
JOHN COOKSON JOHN COOKSON is online now
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It is normal for a warmed up engine to run correctly with the choke open. To start the engine it is normal to have to use the choke (ie choke closed). If the engine will only run with the choke closed or partially closed when it is warmed up it means the mixture is lean.
Once you have free flow of gasoline at the correct pressure to the carburetor report back with any problems you are having. We'll go from there. A fuel pressure gauge would help with the diagnostics. Electronic or mechanical fuel pump?

ex TRUE GRIT
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  #3   IP: 155.186.122.195
Old 06-08-2021, 10:38 AM
Dave Neptune Dave Neptune is offline
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If you have room just add enough line to create a 360* loop with a bit more line OR change the angler of the fitting or the fitting itself.

A pic of the setup would be good.

Don't worry about the carb until you KNOW it is getting enough fuel, as per John's comments.

Also a kink in a fuel line is dangerous and covering it with a bigger hose will only hide the possible kink, not good.

Dave Neptune
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  #4   IP: 108.51.19.207
Old 06-09-2021, 11:27 PM
svsonora svsonora is offline
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Thanks guys. I fixed the kink -- went to a longer line as I had plenty of room. I saw the old line, and while there was a mild kink, there definitely was still enough space for fuel to pass through.

I got the engine tuned again to run, warmed up, under load, etc.

Seems the culprit is the adjustable main jet that I installed. People were right - seems I'm going to be constantly adjusting this thing! Argh.

I wonder if I should just go back to a fixed main jet. Theoretically, I should be able to set the adj. main to the exact same specs as the fixed jet right?
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  #5   IP: 70.185.5.62
Old 06-10-2021, 11:24 AM
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roadnsky roadnsky is online now
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Quote:
Originally Posted by svsonora View Post
Seems the culprit is the adjustable main jet that I installed. People were right - seems I'm going to be constantly adjusting this thing! Argh.

I wonder if I should just go back to a fixed main jet. Theoretically, I should be able to set the adj. main to the exact same specs as the fixed jet right?
Not to question your installation skills...

• When you removed the original jet, did you also remove the washer?
(I want to make sure you didn't end up with TWO washers installed)

• Be sure that the ˝" hex head of the needle assembly isn't OVERtightened.
• Once you have a setting that works, you can tighten down the 5/16" nut to lock it in.
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Last edited by roadnsky; 06-10-2021 at 11:34 AM.
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  #6   IP: 100.36.65.17
Old 06-11-2021, 08:42 AM
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edwardc edwardc is offline
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Quote:
Originally Posted by svsonora View Post
...Seems the culprit is the adjustable main jet that I installed. People were right - seems I'm going to be constantly adjusting this thing! ...
This has not been my experience with the adjustable main jet. I set it once for best mixture at cruising RPM (as verified with a Fuel:Air Ratio gauge) and don't have to touch it again all season.

Keep looking. I think you'll find another cause.
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