Engine Z445/w 27HP Briggs engine surge

[eldowdy]

I've had this since new. Like the title says 27 horsepower Briggs. About 275 hours. Bought it 5 years ago. Has new spark plugs, fuel filter, oil and filter, air filter also. You can't do any adjusting to the carburetor. When it gets to operating temperature it begins to surge up and down in RPM. As soon as you engage the PTO for the blade it smooths out and runs fine. Anybody else have this problem? Solution?

Ed Dowdy
Fithian IL

 

[JD318420]

Is this happening at idle, MT, WOT, ALL?

 

[eldowdy]

It only happens at full throttle (mowing) and with the blade disengaged. Runs fine with the blade engaged and if throttled back to idle when not.

Ed

 

[JD318420]

Sounds like the high end of the throttle needs adjustment. Can the high end speed be adjusted with the throttle cable/governor? What does the engine manual say? Can you get the pdf file of the engine manual from the briggs web site?

 

[eldowdy]

I don't know if it can be. I will see if I can get the .pdf.

Ed

 

[ILENGINE]

Your symptoms point directly to the classic dirt in the idle circuit of the carb. Need to remove and clean the carb, and install a repair kit.

 

[eldowdy]

Sounds good. I see there are no adjustments on this one. I have no experience rebuilding a carb. Would it be possible for a novice to do without specialty tools?

Ed

 

[ILENGINE]

You don't need special tools, just go slow, take pictures especially of linkages, and pay attention to the small things, and don't stop anything that you may need later. get some thin wire to push through all small openings and make sure they are clean. And use spray carb cleaner to back flush all passages.

 

[eldowdy]

Thanks very much for the advice!

Ed

 

[eldowdy]

Ordered the parts today!

Ed