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Rick, Factory Authorized Trainer
Category: Small Engine
Satisfied Customers: 8063
Experience:  Outdoor Power Equipment technical trainer since 1990, covering eight states.
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Engine bogs down and quits at full throttle and/or under load.

Resolved Question:

Engine bogs down and quits at full throttle and/or under load. If I hurry and throttle back to idle it will stay running. Usually happens after 5-10 minutes of run time. Been thru 3 carbs. After carb change works good for a month or 2 and then back to same problem. Ground wire to coil was removed at the 2nd carb change, so mag is not getting ground signal.
Submitted: 7 years ago.
Category: Small Engine
Expert:  Rick replied 7 years ago.
Did you replace the entire carburetor, or just the plastic bowl portion? What spec number is XXXXX? Does the problem continue if you run with the fuel cap on the tank loosened?

Edited by Rick on 7/29/2010 at 4:42 PM EST
Customer: replied 7 years ago.

Hi Rick,


Changed the entire carb.

I have loosened the fuel cap and even removed it - same problem

Carb p/n 640330

Expert:  Rick replied 7 years ago.

What is the fuel quality where you are at? Is the fuel less than 3 weeks old? Have you tried swapping out the ignition coil to see if it's failing?

Customer: replied 7 years ago.

I figured it out. After the engine quit at full throttle II snatched the float bowl off. It was almost dry.. Turned float bowl upside down to check for float and needle/seat for movement. Hardly any travel (way less than it should have been). Moved float up and down while blowing thru inlet, very little to no air coming thru needle seat regardless of float position. Float is a 1 piece arrangement with no adjustments. I tried to bend/adjust in float attach area and 2 of the little struts broke, but the main attach struts remained intact. Turned float bowl upside down again and had normal float travel and air would start and stop when blowing thru the inlet. Re-installed float bowl and fired her up. Worked great under all load conditions. Don't know if this was a manufacturing defect, or the float deformed over time, or the needle seat shifted upward over time.

NOTE: When installing the jet pipe in the bore of the float bowl I found it works the best when you push it most of the way down the bore (not all the way) and having the holes in the jet pipe facing the shut off solenoid.

Expert:  Rick replied 7 years ago.
Really glad you got it going, what happens sometimes on those carburetors is that the seat will raise up in the cavity and shut the fuel off too soon. They started using a stainless steel circlip on many of these carburetors to hold the seat in place to prevent this from happening. Best of success in all your hands touch.

Edited by Rick on 7/31/2010 at 6:22 PM EST
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