Briggs Surges and Hunts

[dennis]

Engine....M 80202, Type 4012, Code 91xxxxxx?

This is a horizontal shaft engine with an air vane governor and pulsa jet tank mounted carb. It had been left out and gas tank had water in it. Took carb apart and cleaned it, including removing welch plug. Put in new diaphragm kit and mixture needle. Cleaned tank well. Put back together and it hunted and surged after running fairly smoothly for about a minute. Noticed some seeping gas around base of carb. Took apart, and doubled carb/tank gasket. That took care of leak. The intake gasket looks to be in good shape. Still surges. When I hold throttle at carb steady, it runs smooth, so don't think it is a carb problem. Besides the possibility that intake gasket is not sealing, what else could it be? The gov linkage from air vane is clear. Really don't see any adjustment there. I noticed a little oil on one side of head gasket. Could a leaking head gasket cause surging? Any suggestions? Thanks.

[bgsengine]

Head gasket can cause surging especially after warm up as you seem to have experienced. You might also check the RPM adjustment and the governor spring condition and check for correct top no load RPM. Also may want to verify the air fane moves absolutely freely for its full length both ways , check for any binding or build up that can make it stick in spots..

[KE4AVB]

Dennis can you double check your engine numbers? I don't find a 080202-4012 listed. The type number doesn't exist for the model number. I found the following number with that type for the 080000: 080232-4012-01.

Did you remove both welch plugs? On this carburetor it shows two of them in the ipls. One for the bleed holes and one at the end of the tower. I haven't seen one these carburetors with a welch plug at bottom of the tower before but on the versions similar I have seen the tower passages to get plugged up and I have had to remove the steel plug balls to clean the rust out of the passages.

Mentioning rust the steel fuel tanks used on the horizontals tend rust causing carburetor problems I replace quiet a few of them because of this.

[dennis]

Thanks for info, bgsengine and KE4AVB. Will check all you mention.....You are right...KE4AVB. Sorry..... I was away from my shop and trying to do it from memory. Won't do that again.

Here is correct info... Model 80202, T 4017-01, C 91061803. I sure didn't see a welch plug at the end of the tower. I can squirt cleaner all the way through. There is a ball plug. Only other welch plug, besides bleed holes, is at the end of carb.....the big one about inch diameter or so.

One other question.....I noticed an oriface in the bottom of carb that is directly connected to one of the screw holes on top of carb where air filter base screws in. Is this some sort of breather? It seems that it would seal completely with air filter base on.

[KE4AVB]

Sorry about the welch plug question for the tower, the IPL I was looking at didn't have the date codes referenced. It appears to be something Briggs was doing in the late 80's and yours is a 91 model.

Went to the shop pulled a similar carburetor off a 5 hp to look at that passage. On the one I have there is no orifice there just vents the tank although looks like it could have at one time had been a passageway drill over to the fuel pump area at least that is how the casting looks. Someone with more experience with these may chime in.

I am getting a little rusty for lack of repairs on these in the last couple years. Maybe next year things will pickup again after the move and as my mind settles back into working on these engines. There for awhile I didn't know if I was coming or going with my mother having dementia. It was a full time care thing with very little rest.

[dennis]

Thanks, KE4AVB....

I know what you mean about laying off working on these things and then coming back to it. Good luck with the move and getting back to normal. Any kind of dementia is just plain hideous.

Dennis