Briggs 19 HP OHV

Kevin S SC · Apr 14, 2013

I have a engine that the rpms bounce. I have cleaned the carb and it still does it. It doesnt have needle adjustments. If I hold the govener or when I engage the blades it will run smooth. Do ineed to adjust the govener or valve.

Bob M · Apr 14, 2013

Assuming the governor linkage works freely without any trace of binding the most likely cause is a lean fuel mixture.

With the engine warmed up and running at speed, try SLOWLY pulling the choke closed. If you find a choke setting where the RPM's settle and the engine runs smoothly you've found the problem.

Possible causes:

1 - Vacuum leak between the carburetor and the cylinder head(s). Look for loose attachment screws, bad gaskets, failed O-rings, etc.

2 - Partially clogged fuel metering orifice inside the carburetor

3 - Carb float level is low.

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2 or 3 of course require going inside the carburetor for cleaning/inspection.

Pappy · Apr 14, 2013

We have a 17.5 Briggs on a lawn tractor that did the same thing this spring on first start up. It was low on fuel so i sprayed about half a can of Gum-Out into the tank and ran it awhile. It smoothed out and ran fine after a few minutes.
Might have been a gummed up carb.

UncleTom · Apr 14, 2013

And possibly the electric fuel shut off solenoid on bottom of carb acting up.

Kevin S SC · Apr 14, 2013

Pulled carb back apart everything appears clean I run a welding tip cleaner and air thru every hole. The govener is free. I took off the manifold, it and all gaskets look good. The float is all plastic and I think non adjustable. And the electric fuel cutoff works good I even took the plug off the top and tried it. It does smooth out with the choke. I think its a vacumme leak Ill take it apart and clean and inspect until I figure it out Thanks Yall.

old · Apr 14, 2013

Yep common problem with them and a carb jet clogged up. The main on them can be open but if the idle is clogged it will cause that as per B/S info I got for a lawn mower repair guy I know. Or the gov spring is weak either one or both will cause that

LeonardWD45 · Apr 14, 2013

Kevin, had this problem on dad's 18.5 hp Briggs. Couldn't find the problem until my brother came up to the farm in August a couple of summers ago. He worked on it and found that the needle seat had somehow slid out a bit. He reset the needle seat and the problem disappeared.

Leonard

Kevin S SC · Apr 14, 2013

Got it, must have been the idle jet. A little resistance with sticking wire in it and slipped in another 1/8 in. I didnt think the idle jet would make it not run good wide open! Thanks again all.

Briggs 19 HP OHV

Kevin S SC

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Bob M

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Pappy

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UncleTom

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Kevin S SC

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old

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LeonardWD45

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Kevin S SC

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