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  5. Carter YH Carburetor Troubleshooting

Carter YH Carburetor Troubleshooting

I have successfully rebuild my carburetor with everything except number 23 on the parts list, I have put the needle in the proper place, but there is a circle with an arrow that has a spring with the ball that goes on top of the needle number 23, and my carburetor did not have either of these components in it, and the kit did not come with the spring and ball assembly.

Kits include the check ball, but not the spring, or cap that goes on top. Some YH carburetors use a check ball, spring, then the cap. Others use a tapered check weight without the check ball, or spring. Our carburetor kit includes the check weight in case you need one. They get lost easily.

i’m having an issue when I revved the motor up and let it come back to an idle, it stays at a slightly higher RPM and then slowly settles into a slower Idle , Could you please give me a recommendation to cure this problem please?

The problem could the return springs on the accelerator pump diaphragm. Look at the exploded view on your instruction sheet. There are 2 small springs on top of the accelerator pump and 1 big one that goes over the pump at the bottom. Be sure all of the springs are in place. None of the springs are available that we know of. The biggest spring is the return spring which will return the throttle. You can try stretching the spring a bit and see if that helps.

The last thing to do is to put a spring on your throttle linkage to help pull it back.

These YH’s were rebuilt about 6 years ago using Daytona parts rebuild kits and their flat needle and seat design. Had run great after the rebuilds. Then after a fuel pump rebuild this spring, I’m back to the notorious problem of fuel out the aft carb throat. Pressure has not been checked. Float levels check to factory spec 9/16″ front and 7/16″ rear. Per your YouTube tutorials, blowing into the fuel inlets the needle/seat seem to not leak. Also per your tutorial the metering rods check as well as the accelerator pumps. Hard to tell with these carbs sitting down low in the engine valley but it looks like I’m getting fuel dripping out from the throttle butterfly shafts. Rebuild again?

To me, it’s suspicious that this started after rebuilding the pump. I would test the pump pressure before going any further. Not sure what the actual spec is for pressure but imagine it isn’t more than 4 lbs. You may have to add a regulator.

The other thing that brings up a yellow flag is the fact it’s been 6 years. Being a marine carburetor I’m sure it sits around a lot. Your carburetors are probably dirty and that will cause flooding.

Gas is flooding out of the carburetor

The most common problem is dirt, or bad needle & seat.
Test your needle & seat – Did you damage the viton tip when adjusting the float? There may be dirt in the seat. Be sure the gasket is under the seat.
Has your engine been sitting for months? If so then the gas has probably turned and coated the inside of the carburetor. A thorough cleaning is in order.
Test the fuel pump pressure for not more than 4 lbs.
Does the float have fuel in it?
Check float level, but unless it’s way off, then not the problem.
Is the float clear on all side and not rubbing.
Move float up and down to make sure it isn’t catching.
Is there a return line on the fuel filter? If so make sure it isn’t disconnected.
Fuel filters might need to be changed.

Turn Off Engine and Fuel Runs Into The Throat

This is usually caused by a vent, or check ball problem.

  • Is the gas cap vented? If not you will usually get a vacuum suck when loosening the cap after a long drive.
  • Make sure any vent tube coming out of the carburetor, or hose isn’t blocked off. The fuel bowl needs to be vented.
  • A leaky check weight in the main discharge can cause this. Tap on the ball (not too hard) to form a good seat.
  • Check float level.
The most complete carburetor kit available for the Carter YH. Includes the spring loaded needle & seat
Updated on 04/13/2022

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