Try static adjustment of the governor
Briggs 8hp I/C - High Speed Surge
I have an old briggs flathead on a tiller with a three screw Flo Jet carb. The model/code is 195432-0291-01. I just finished up a rebuild on this engine with a 10 over rebore, and am trying to get it dialed in.
I'm having a terrible time getting rid of a high speed surge. It will idle just fine, nice and smooth. But when I throttle it up the governor starts hunting. It does not hunt when under load.
I've tried many of the common fixes, so am looking for some help on uncommon fixes and/or things I may have overlooked.
What I've done so far:
1) Cleaned carb myself 2x with new kit. No better.
2) Cleaned fuel tank and shutoff valve. Completely replaced fuel line and filter. No better.
3) Took carb to shop and they ultrasonically cleaned it. A bit better but still there.
4) Sprayed carb cleaner around joints. No noticible reaction.
5) Did a static governor adjustment. Nothing.
Help please! I've spent way too much time with this engine and my wife is starting to give me the evil eye every time I head to the garage. :14_6_5:
I'm having a terrible time getting rid of a high speed surge. It will idle just fine, nice and smooth. But when I throttle it up the governor starts hunting. It does not hunt when under load.
I've tried many of the common fixes, so am looking for some help on uncommon fixes and/or things I may have overlooked.
What I've done so far:
1) Cleaned carb myself 2x with new kit. No better.
2) Cleaned fuel tank and shutoff valve. Completely replaced fuel line and filter. No better.
3) Took carb to shop and they ultrasonically cleaned it. A bit better but still there.
4) Sprayed carb cleaner around joints. No noticible reaction.
5) Did a static governor adjustment. Nothing.
Help please! I've spent way too much time with this engine and my wife is starting to give me the evil eye every time I head to the garage. :14_6_5:
1 - 16 of 16 Posts
I had done that, unfortunately. The governor arm goes down and shaft turns clockwise to get to full throttle. I loosened the governor bolt, pushed the arm down and turned the shaft as far clockwise as it would go. I think that's the correct procedure, from what I've read?
I've had the same problem with an 8hp Briggs and seen it in others. This was taken from Miller's site and explains some of my own engine problems--
"If a stock engine runs with a "hunting" sound, and the governor lever moves side to side while running at around 3,600 or 4,000 rpms, and if adjusting the carburetor or adjusting the rpms doesn't fix the problem, then perhaps the governor gear/flyweights assembly is worn on its stub shaft, or the shaft itself is worn. This will cause the governor gear to wobble around on its shaft, which will cause the governor to oscillate. And the engine will run erratic. To fix this problem, the governor gear and shaft must be replaced with new ones, or a cast iron governor gear. (Nylon governor gears are known to wear more often than cast iron ones.) "
This is a Kohler site so I only assume it might apply to a Briggs.
"If a stock engine runs with a "hunting" sound, and the governor lever moves side to side while running at around 3,600 or 4,000 rpms, and if adjusting the carburetor or adjusting the rpms doesn't fix the problem, then perhaps the governor gear/flyweights assembly is worn on its stub shaft, or the shaft itself is worn. This will cause the governor gear to wobble around on its shaft, which will cause the governor to oscillate. And the engine will run erratic. To fix this problem, the governor gear and shaft must be replaced with new ones, or a cast iron governor gear. (Nylon governor gears are known to wear more often than cast iron ones.) "
This is a Kohler site so I only assume it might apply to a Briggs.
I had one do similar things and I found there was a spring missing,that goes over the linkage rod fron the govenor arm to the carb's throttle lever..
The spring slides right over the link rod,and hooks onto both the govenor arm and the throttle lever's holes and keeps them "taught" so any slop in the linkage holes wont let the throttle lever dance around and let the speed fluxuate,it only takes a few thousandths of movement to make a large difference in the speed...it'll hunt up and down constantly instead of staying steady..you can "almost" tune it out by fiddling with the main mixture adjustment,but not quite!..
The spring slides right over the link rod,and hooks onto both the govenor arm and the throttle lever's holes and keeps them "taught" so any slop in the linkage holes wont let the throttle lever dance around and let the speed fluxuate,it only takes a few thousandths of movement to make a large difference in the speed...it'll hunt up and down constantly instead of staying steady..you can "almost" tune it out by fiddling with the main mixture adjustment,but not quite!..
I don't see a missing spring on the parts diagram. I'm also not seeing side to side play in the governor when running. But it sure seems like the issue lies in the governor setup somewhere.
The reason I say that is I am able to get smooth, steady running at high speed by holding the throttle plate manually. If it will do that, it seems to me that it would be pointing at the governor/linkage, and I should be able to rule out ignition, ring, carb, or valve issues. Of course, that's my uneducated beginner opinion.
I don't have much in the way of adjustment options on the governor lever linkage. I guess I could try replacing the spring. It's probably cheap and maybe the prior owner put a different one on there.
The reason I say that is I am able to get smooth, steady running at high speed by holding the throttle plate manually. If it will do that, it seems to me that it would be pointing at the governor/linkage, and I should be able to rule out ignition, ring, carb, or valve issues. Of course, that's my uneducated beginner opinion.
I don't have much in the way of adjustment options on the governor lever linkage. I guess I could try replacing the spring. It's probably cheap and maybe the prior owner put a different one on there.
That's what I'd try,maybe just tighten it temp..to see?TH might have it--on a B&S you'll have a tiny hair sized spring along w/the throddle shaft--if broken--it'll do the same thing you got-Now how on earth would I know that??:00000061:I guess I could try replacing the spring. It's probably cheap and maybe the prior owner put a different one on there.
Interesting. You are the second person to mention this second spring but I've not seen it anywhere. I can't find it on a parts diagram either. Taking out the slack in the governor linkage would certainly make sense. I wonder if I could rubber band it together or something temporarily and see if that helped or not...That's what I'd try,maybe just tighten it temp..to see?TH might have it--on a B&S you'll have a tiny hair sized spring along w/the throddle shaft--if broken--it'll do the same thing you got-Now how on earth would I know that??:00000061:
If holding the throttle still makes it stop surging,its likely the spring problem I mentioned..if it were the govenor,you'd feel it wanting to open and close the throttle while your trying to hold it steady...
On mine,I couldn't find the correct spring,but found one close to it on a junk push mower with a briggs engine..any similar spring would work if you can find one small enough in diameter and about 1" shorter than the distance between the holes the govenor link to throttle lever goes in..the spring is about 1/8" in diameter with a 1/16" hole in it,that the link slides right thru...its similar to one on a ball point pen only longer,I would guess maybe 3" long,with 1" of it being the coils,the rest is straight with the hooks on each end that go into the linkage holes..it holds tention against both the carb throttle lever and the govenor arm so there is no play ,and they'll move in unison together..
On mine,I couldn't find the correct spring,but found one close to it on a junk push mower with a briggs engine..any similar spring would work if you can find one small enough in diameter and about 1" shorter than the distance between the holes the govenor link to throttle lever goes in..the spring is about 1/8" in diameter with a 1/16" hole in it,that the link slides right thru...its similar to one on a ball point pen only longer,I would guess maybe 3" long,with 1" of it being the coils,the rest is straight with the hooks on each end that go into the linkage holes..it holds tention against both the carb throttle lever and the govenor arm so there is no play ,and they'll move in unison together..
Ahh, that helps. I'll attempt to see what I can scrounge up around the garage and give it a whirl. It would be really nice if the fix is this simple.
You could use fishing line and a ballpoint pen spring if you are good at tying knots. Just a tiny bit of tension is needed to keep the parts all shaking at the same speed, but it sure makes a difference when they do.
tom
tom
I sometimes(mostly) give hard to follow steps.The spring I'm refering to is around the throttle shaft.:hide:
I call it a rod . cannot recall what ipl calls it .I sometimes(mostly) give hard to follow steps.The spring I'm refering to is around the throttle shaft.:hide:
When you cleaned the carb did you remove the main nozzle and make sure all of the tiny holes were clean?
If not, that could be a part of the problem.
Dave
If not, that could be a part of the problem.
Dave
I did find the spring on a similar Briggs 8hp IPL. I forget the part number, but for $4 I told them to order it. I'm also replacing the throttle rod and governor spring for good measure. There is definitely slop in the linkage, so maybe, just maybe this will do it. They should be in tomorrow or Friday. fingers crossed - I've learned not to get too hopeful with this thing.
The main nozzle is actually brand new. But I did pull it back out and cleaned out all the holes just in case. IIRC there were really small ones close to the base, and then then big ones in the middle. I also made sure the one on the end was free for the idle jet. It could still be dirty, but the odds are low. Stranger things have happened though.
I'll keep ya posted on progress this weekend. I so want to call this thing done!
The main nozzle is actually brand new. But I did pull it back out and cleaned out all the holes just in case. IIRC there were really small ones close to the base, and then then big ones in the middle. I also made sure the one on the end was free for the idle jet. It could still be dirty, but the odds are low. Stranger things have happened though.
I'll keep ya posted on progress this weekend. I so want to call this thing done!
Success! I owe you all a cold one or three! Who would have thought a $4 spring would be the cause of all my problems. Woo hoo! I'd really reached the end of my rope with this one.
It runs OK with no load at high throttle now. A bit of popping, but it settles right down once I begin tilling. Now, a couple more odds and ends to clean up on the old Horse and I think I can finally call this project done!
It runs OK with no load at high throttle now. A bit of popping, but it settles right down once I begin tilling. Now, a couple more odds and ends to clean up on the old Horse and I think I can finally call this project done!
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