18 HP Briggs engine problem...

15 years ago

I have an 18hp Briggs engine off of my Craftsman LT1000 riding mower, engine model# 31H777, type# 0202-E1. I had to rebuild the engine last fall as the previous owner had the common starting problem that has been discussed at length in other forums but did nothing about, the engine backfired several times and blew one of the rings. So I replaced all of the rings, honed the cylinder, replaced all of the gaskets, adjusted lifters back within specs, and verified the timing was dead on upon re-assymbly. When I remounted the engine I made sure all of the linkage for the choke/throttle were hooked up properly and it purrs like a kitten now, BUT, after the engine runs for 10 seconds the RMPs start to sky rocket unless the engine is put under load. Once under load the engine will run perfectly until the load is taken off and then the RMPs take off again.

What was the top end of the revs now seems to be the low end, this leads me to believe that I did not reinstall the slinger/governer properly. Does anyone know the proper reinstallation procedure or placement of the governer? I can not seem to find it anywhere. Or is it possibly a different problem?

Thank you for your help

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Comments (3)

walt2002
15 years ago
"Does anyone know the proper reinstallation procedure or placement of the governer? "

Well that is pretty well straight forward. I don't see where you mention setting the "static governor setting" before starting the engine.

Loosen the clamp holding the governor arm to the governor shaft where it comes out thru the engine block. Hold the throttle in wide open position, rotate the shaft coming out of the engine clockwise as far as it will go. While holding both in position, with your 3rd hand, re-tighten the clamp holding the arm. There will not be very much movement in the shaft coming out on the engine in either direction.

If this doesn't help, you have a problem inside. Be aware that the IPL shows that your engine has an oil slinger/governor. If so and the governor is not working right, there is a distinct possibility the the oil slinger is not working right either.

Walt Conner
wlfman
Original Author
15 years ago
Thanks Walt!

I will give that a try.

Eric
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I have a Craftsman mower/tractor with a Briggs & Stratton 31H777 0297 E1 18 hp. It has always run great until it didn’t. lol Here is what it does. I took the mowing deck off and only use it to tow the little yard trailer. It starts and runs at low idle just fine, sounds good and runs smooth until I bring up the throttle. Somewhere between 1/4 & 1/3 throttle it starts to run rough and the higher the throttle the rougher it runs and the exhaust turns black. When I pull back on the throttle it evens out and will run that way for as long as I want, however if I put a load on it and try to pull the trailer it gets bad again. Here is what I have done: Cleaned the carburetor. Rebuilt the carburetor. Replaced the fuel line & filter, and made sure the tank was clean of debris. Checked to be sure that fuel was flowing freely. Pours out of fuel line next to carburator at a very fast rate. Changed oil & filter. Bought a new carburetor. Checked to be sure the anti-fire solenoid was working. Tried running it without the anti-fire solenoid and the hole plugged. Adjusted the valves. Removed and checked the flywheel key, reinstalled. Checked and reset the gap on the ignition module. Pulled the head cleaned the combustion chamber and checked to be sure there wasn’t any carbon under the valves, installed new head gasket and readjusted valves. New spark plug. New fuel cap and tried running it without the cap. Checked to be sure the choke is fully open. Please let me know if I missed something besides taking it to the shop or flat out replacing it.
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wlfman
Original Author
15 years ago
"Loosen the clamp holding the governor arm to the governor shaft where it comes out thru the engine block. Hold the throttle in wide open position, rotate the shaft coming out of the engine clockwise as far as it will go. While holding both in position, with your 3rd hand, re-tighten the clamp holding the arm. There will not be very much movement in the shaft coming out on the engine in either direction."

Ok gave this a try and the same problem exists. After the engine is started with the throttle full choke then backed down a bit, the enigne runs great and will run great for a long time. When I try to throttle down to shut the engine off, nothing happens, and secondly when the engine is hot and the load is removed the engine revs want to sky rocket.

So I took the engine back off the chassis and took of the bottom of the engine to gain access to the governor/oil slinger. Something just does not seem right. I am not sure where the g/os is suppose to be positioned prior to putting the cover back on, and how much play there should be in the arm that compresses the governor.

I have taken a few pictures of the engine and posted them on my website. Just follow the link to see the pictures, once at the index page you can click each picture for a larger view.

http://www.jehorner.org/engine/arles_gallery/18hp%20Briggs.html

Thanks a million for your help!!!!

Eric

Here is a link that might be useful: pictures of the engine

18 HP Briggs engine problem...

Comments (3)

walt2002

wlfman
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18 HP Briggs engine problem...

Comments (3)

walt2002

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