Hi, new member here, yes I have been bitten. The '73 SS16 is my second purchase in a 2 month time line I also have a ST 16 1974 vintage. My SS16 with the Onan BF/MS engine runs great at full throttle but at partial it surges or hunts, and it will just die if you try to idle it. I am wondering if this is only related to the carburetor or is the governor a known culprit for this. I will be starting a carb inspection soon so I can get this right before we get any more snow here in Michigan. Motor does not smoke, does not make any unusual noises.

1973 SS16 Onan -engine surges when running
#1
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Posted January 11, 2021 - 09:52 AM
- jcp7hp said thank you
#2
ONLINE
Posted January 11, 2021 - 01:12 PM
Hi, new member here, yes I have been bitten. The '73 SS16 is my second purchase in a 2 month time line I also have a ST 16 1974 vintage. My SS16 with the Onan BF/MS engine runs great at full throttle but at partial it surges or hunts, and it will just die if you try to idle it. I am wondering if this is only related to the carburetor or is the governor a known culprit for this. I will be starting a carb inspection soon so I can get this right before we get any more snow here in Michigan. Motor does not smoke, does not make any unusual noises.
Hello, . Id recommend cleaning up the jets with a wire brush or just buy new jets or a carb. Link here!
https://www.ebay.com...2sAAOSwHVVf6n2K
- TinkerSmith said thank you
#3
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Posted January 11, 2021 - 01:24 PM
sounds like the idle jet is clogged
- jcp7hp and TinkerSmith have said thanks
#4
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Posted January 11, 2021 - 03:58 PM
It might have some water laying in the bottom of the carb or your jets are plugged or it's adjusted incorrectly. If taking it apart completely and giving it a very good cleaning and adjusting it does not help it could be a fuel pump issue.
This ethanol gas is very very hard on the fuel pump diaphragms and rubber valves inside of fuel pumps. What ever you do, do not buy a cheap $10 aftermarket fuel pump. I've had nothing but bad luck with those aftermarket pumps and went though 3 of them in less than 1 year on my mowing tractor. I got 2 days out of 1, 1 month out of the 2nd 1 and 8 months out of the 3rd one before I bought a OEM pump for $48.
If your fuel pump is rebuildable? buy a rebuild kit for it if you can find 1.
- chieffan and jcp7hp have said thanks
#5
ONLINE
Posted January 11, 2021 - 08:59 PM
Most likely you have a two piece intake and those are known to leak. Or your pilot jet is clogged or it is just set to lean. I am not sure about it being the fuel pump because most of the time when you have an issue with a low flowing fuel pump you have issues with high rpms and load not the opposite.
- Leonard VanCamp, chieffan and jcp7hp have said thanks