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JohnF2015
JohnF2015, Small Engine Technician
Category: Small Engine
Satisfied Customers: 1016
Experience:  Owner/Service Technician at S & J Small Engines
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2265 SUA new carb still hunting after replacement. Gaskets

Customer Question

2265 SUA new carb still hunting after replacement. Gaskets were siliconed for possible air leaks. Any ideas?
JA: I'll do all I can to help. How long have you been dealing with this?
Customer: Well today with the new carb.. and before with the original. Thought ethanol ruined the original.
JA: Do you plan on doing the work yourself?
Customer: yes
JA: Anything else we should know to help you best?
Customer: the machine snow blower is not that old and in really good shape.
Submitted: 1 month ago.
Category: Small Engine
Expert:  Matt replied 1 month ago.

Hello

I'd agree that this could be a air leak

The best way to locate a leak is to have the engine running and warm and then spray lighter gas/propane or brake cleaner around each joint in turn. If the engine rev's up you've found your leak.

Now you might think that spraying lighter gas around a hot engine isn’t wise, however the flash /ignition point of gas is about 400°C so you need a naked flame or spark to set it off and I’ve used this method for many years without incident.

Work your way through each possible joint one at a time and you should find it. I use a slightly flattened piece of brake pipe and some rubber hose from the can of lighter gas to provide a spraying 'wand' and allow a direct blast of gas into each area, especially those difficult to reach with large implements.

Customer: replied 1 month ago.
Did all that...
Expert:  Matt replied 1 month ago.

Hello

in that case then I'd replace the spark plug with a new part

You can also try spraying some water on the coil pack with the engine running. It is possible the coil is faulty and causing the misfire. If you see sparks arcing with the water, then replace the coil.

Customer: replied 1 month ago.
Its not missing it is hunting, surging in rpm. Spark plug has nothing to do with this condition.
Expert:  Matt replied 1 month ago.

Hello

in that case how have you set the idle mixture ? as if its too lean this too will tend to make an engine hunt as you describe

there's usually a screw for idle that should be provisonally set 2 turns open from fully closed

Customer: replied 1 month ago.
Are you familiar with the engine and carb. config? There are NO adjustments. It's a fixed main jet.
Expert:  Matt replied 1 month ago.

OK

I'll opt out and get someone else invovled

good luck

Expert:  Vince O. replied 1 month ago.

Hello, is that an MTD Chinese engine 265 SUA?

Expert:  Vince O. replied 1 month ago.

Does it look like this?

Customer: replied 1 month ago.
That be the one
Expert:  Vince O. replied 1 month ago.

Sometimes a governor adjustment will fix that especially if the carb was removed. Pulling on the linkage to remove it from the carb can knock it out of whack. I think I have a shop manual.

Customer: replied 1 month ago.
Thanx !!! This was hunting like this before I removed the carb. I has to be something else. I'm ready to change the mounting block and all the gaskets. It doesn't add up.
Expert:  Vince O. replied 1 month ago.

If there were an air leak it would be hard to start and not run at the higher rpm's

Customer: replied 1 month ago.
It starts ok... but hunts, surges, at high speed. I've sprayed carb cleaner around the inlet gaskets (back side of carb) and get no change in the running of the engine. That is what has me puzzled. You would think that if there were an air leak, that the spray would alter the running of the engine, as it was drawn in.
Expert:  Vince O. replied 1 month ago.

Did you remove gas tank and try adjusting the governor?

Customer: replied 1 month ago.
No... This machine is relatively new. I don't see that as possible. If I partially choke the carb, it will smooth out. Classic too much air in the mix.... I have had these problems before with other Chinese engines, only ALL that I've done to this one, has not rectified the problem.
Expert:  Vince O. replied 1 month ago.

OK, I gave you my input and will opt out. Good luck.

Expert:  JohnF2015 replied 1 month ago.

Hi, my name is***** will be assisting you.

I was reading through the prior conversation and I would suggest that you have a partially blocked main fuel jet or nozzle. I know that you have indicated that you replaced the carburetor with a new one but it is possible that the jet may not have been cleaned thoroughly during manufacture.

What happens if you hold the governor linkage steady while the engine is running?

I do agree with prior comments that if it were an air leak the engine would be hard to start and if you sprayed around the sealing surfaces while the engine was running you should have noticed a change in the way the engine was running.

This carburetor has a small fixed jet in the top of the carburetor just under the idle adjustment screw that can be removed and cleaned as well however it normally only affects the idle performance of the engine and not the high speed performance.

Customer: replied 1 month ago.
John, It is a brand new carb.
Expert:  JohnF2015 replied 30 days ago.

That really doesn't matter, I have been in the repair business for 28 years and it can happen. I have seen anything from a small shaving left behind to items deliberately left in the carburetors by upset employees that can cause issues. Yes, I understand that it is a new carburetor and one would think that you could rule it out but that is not always the case.

Since you are saying that you can choke it and it seems to run better, it really makes me believe that there is something in the jetting of the carburetor.

Customer: replied 28 days ago.
John, The original carb. (which I removed and cleaned, wasn't dirty) and reinstalled was doing the same thing. I thought the original might have been plugged, even after disassembly all the way to the jet, and that is why I opted to replace it. It cant possibly be two bad carbs. My luck isn't that bad....lol