Nikki Carb flooding

ganier57 · Aug 22, 2012

I have a Husqvarna YTH2348 with a Briggs 23 HP model 445577-0755-E1 engine. It has a Nikki 698494 carb.

The engine will start but only run a few seconds before the carb starts flooding and gas and oil blow out the exhaust.

The carb has been cleaned and rebuilt twice and it does the same thing. With the fuel bowl full I took the gas line off at the pump and tried to blow back to the carb and couldn't so I think the float needle is sealing good. The electric fuel shut off was tested and is working fine.

Can anyone help me?

chance123 · Aug 22, 2012

I hate these carbs. The main jet is a press fit with o-ring into the bottom of the body of the carb. I can't count the times I've had to re-seat that jet until it stayed put. On one occasion, I couldn't make it stay and had to replace the whole carb. I can't understand why they did this. Vibration along with gravity could dislodge that tiny jet.

pugaltitude · Aug 22, 2012

If i remember right the float can go both ways (could be thinking of honda gxv620)
Have you got it the right way round.
Main problem would be float and needle not sealing.

EngineMan · Aug 22, 2012

pugaltitude said:
If i remember right the float can go both ways (could be thinking of honda gxv620)
Have you got it the right way round.
Main problem would be float and needle not sealing.

Going by the manual float can only go one way, and has you say it can only be the float needle not sealing,.
take it off the engine take off the float bowl, turn it up side down wet the needle and seat should hold at 2psi.

mr rojo · Sep 12, 2012

hey guys ,i have come up with a fix for the flooding /belching black smoke/runnin like crap nikki carbs!!! remove carb ,then remove float bowl ! carefully remove float plate assm exposing main jet and transfer tube ,then find an o-ring that fits snug in the float plate transfer tube housing,hold in place with a dab of axle grease if needed!! reassemble float plate and carb and install on engine! change plug or clean existing one,crank and run!!!works like a champ!! did it to my murray rider with a 12.5 hp b&s /nikki carbed and proceded to cut my 2 acre lawn with no more carb problems... hope this helps everyone out there with the dreaded nikki carbs........ mr rojo

pugaltitude · Sep 12, 2012

Different carb than the one that the op was asking about.
If you fit the o-ring correctly on the type you are talking about then you hardly have many problems.
If in doubt just replace with the correct Briggs one that is listed under your Model, Type and Code.

oldebondo · Apr 15, 2015

After trouble shooting the NIKKI flooded carburetor, running rich problem with my 10.5 I/C Intek Briggs and Stratton engine, I found the problem: the round o-ring of item 137A, after 6 years of service, compressed into a rectangular cross section. It is supposed to be a typical O-ring with a round cross section. I replaced the O-ring with one that was close in size because that was what I had available. It started right up and ran fine. I hope this will help someone from replacing the Float Needle, Float, Main Jet, etc. Good Luck!

EngineMan · Apr 15, 2015

Thank you for your feedback, am sure it will help someone with the same problem.:thumbsup:

Nikki Carb flooding

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ganier57

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chance123

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pugaltitude

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EngineMan

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mr rojo

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pugaltitude

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oldebondo

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