OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines Briggs & Stratton 3.5 over revs

Hi all,
I know this subject has been done to death and I have researched the replies here but I am still having problems. I have an old Victa Vantage with a B&S engine and a pulsa jet carb that I got from the trash. All it needed was an adjustment to the kill wire and all went well so I decided to clean it up, repaint etc. I removed the carby and engine and did up the base and then replaced everything. Now, when it starts, it goes to full throttle. I had full throttle control before I interfered with it so it must be something in the reassembly. I klnow the throttle spring is dodgy and I have a couple of mowers with the same engine so I replaced the springs on the carby with springs from the another mower to test that but the same problem appeared.The throttle cable seems to function properly....What else could it be? Any ideas? Could it be sucking air somewhere - would that do it??

With the engine stopped, move the speed control lever from Stop to Max (tortoise to rabbit) while watching the lever on top of the throttle butterly. Does the throttle move from against the idle stop to wide open? If it doesn't, the governor is in disarray. You may have connected the springs incorrectly, or it may be a disconnected or kinked speed control cable, or even more likely, a bent or disconnected wire link on the governor itself. When you remove the carburetor you have to disconnect that link, then when you reconnect it, it is easy to put it on incorrectly so the throttle is jammed open.

Hi Grumpy,

It's nice to talk to you again. Thank you for the reply. I think you're correct it HAS TO BE the throttle linkage somehow. Tomorrow I'll buy another spring and have a good look at the things you've suggested. I'll let you know how I go. I'll try and post some pictures - before and after.

Thanks sparker, pictures are by far the best way to communicate on problems like this. They also make a much better archive. Please include top views of the governor base plate with the speed control at both maximum and minimum. That should show us the lever positions, whether the wire link it working properly, whether the springs are in the right places, and what the throttle butterfly is doing.

Hi,
Here are some shots I took; The throttle is fully open (off position). I bought a new governor spring ($13.25 here in Mackay) and have added it to the carby. There is a shot of the old spring if you can call it that! However, to no avail as the engine still races away to full throttle. If I manually move the governor it works OK. I notice more tension than I thought would be there on the governor but can't figure out where it is coming from or whether that's normal. Do you think a good clean of the carby would make a difference? I found this on the web it is to do with the governor setting - it might help someone but it did'nt help me:

The Following is an Instruction File I Made for Setting the Governor Arm Correctly. Any Input is Appreciated.
>>If you Removed/Loosened the Governor Arm from the Governor Shaft or Put the Linkage in a Bind when the Carburetor was Removed, then Reset the Governor.
>>**To Reset the Governor; Loosen the Governor Arm Bolt and Turn the Governor Shaft Clockwise Until it Stops.
>>Using the Governor Arm Hold the Carburetor to Full Throttle. Now with the Shaft Full Clockwise and the Governor Arm and Carburetor Held at Full Throttle, Tighten the Governor Arm Bolt.
>>If the Engine Still Runs Full Throttle, then Reverse the Rotation of the Governor Shaft, but Still Hold the Carburetor at Full Throttle with the Governor Arm.
>>**If it Still Runs at Full Throttle, then Check the Internal Governor.**

sparker, those instructions appear to be for an engine with an internal governor, not an air vane governor. Here is what your governor linkage should look like:


As you can see, the diagram of how it is supposed to be, doesn't look much like what you have done at the moment. The governor spring and governor link both seem to be incorrectly connected. The left end of the governor spring should be connected to the hole in the end of the air vane lever, along with the end of the governor link, and the other end of the governor link should be connected to the throttle butterfly.

Hi Grumpy,
Thanks for the input. I don't think my photo's are as clear as I'd like. I have now tried a close up of the area but it's a little blurry and the second one you'll have to turn your monitor upside down. I have the long governor spring (and the smaller spring - not on your diagram)connected to the "eye" of the steel linkage. The linkage is connected to the governor vane at one end and to the throttle at the other end. I think that's the correct position but whether their doing the job....??

I changed the carburetor-no difference. Linkage wrong somewhere? something else? Could it be the breather tube from the crankcase to the carburetor - it is loose and won't screw into the fully tight position and still be able to get the boot to the carby on. Could it be sucking air there? That may sound dumb but don't forget who you're dealing with!

sparker, I can't really find the link that goes from the air vane lever to the throttle butterfly in your pictures, but if you are sure it is there, that is fine. What I do see, and you have mentioned yourself, is a second governor spring that the diagram does not show. I previously had taken this to be the missing link, incorrectly installed.

Does the throttle close when you push the vane away from the flywheel? If it does, but it takes more force than the vane can provide, it sounds like too much spring force. Since you have two springs, where the manual says you should only have one, I suspect you need to remove that small spring that isn't shown on the diagram. Perhaps some previous owner put it on there after he trashed the proper spring, which you have now replaced? It's like when you own a block of flats, sparker: the main problem you always face, is the "tenant's improvements" that don't improve anything, and have to be put back as they were in the first place.

I think the two springs are a later model carby. Here is a shot I stole from another site showing a clear view of the linkage arrangement. That's the same as mine but...it's not working for me. Any thoughts on the breather tube theory?

When the vane moves away from the flywheel, does the lever attached to it foul the breather tube?

No, there's no fouling and I was thinking about it sucking air into the crankcase from that tube and realised that it could not possibly be the problem. It's got me stumped.

Let's try to look at it from first principles. When you put the speed control at minimum, does the throttle close? With the speed control at maximum, if you apply light pressure with one finger to move the air vane away from the flywheel, does the throttle close?

With the throttle at minimum i.e. the stop position (when the coil shorts out on the carby base) the throttle is in the fully open position-just like the picture above. Doesn't sound right does it? Moving the throttle cable makes no difference to the butterfly but changes tension on the springs, I guess so the governor vane can take over.

And yes, If I start the engine and manually move the vane it will control the engine speed. Grumpy, thanks for your help. I am going to sleep on it and have a go tomorrow. If you think of anything let me know.

sparker, something seems to be keeping the vane from moving freely. I suggest you temporarily remove both governor springs, then try to move the vane with very light finger pressure. If there is any resistance whatever, the vane or linkage is physically stuck. Disconnect the link between the air vane's arm and the throttle, and see if the vane is free. If it is, your link between air vane arm and throttle was stuck. If the vane isn't free, loosen its pivot bolt and see what is causing it to stick - the pivot bolt might be too tight.

With regard to your earlier comment that the use of a second governor spring is on a "later model", and therefore applicable to your engine, there seems to be a mismatch of information. As far as I can tell your ignition coil does not have the Magnatron fitted, so your engine is pre-1982.

Post-Edit: I was wrong, the ignition coil is clearly a Magnetron, so the engine is post-1982 (unless the Magnetron had been fitted later).

The one you showed with the second governor spring has a Pulsa-Prime carburetor, not a Pulsa-Jet like yours, and is therefore at least ten years newer than yours, probably more than that. This makes it seem unlikely that your engine had that second, small-diameter governor spring when it was new, or that it should have it now.

Grumpy, that carby appears to be one of the plastic ones, correct me if i'm wrong here, but didn't briggs use metal carby's till quite recently?

Again, i could be very wrong here, Briggs engines are still new to me!

No Ty, that early plastic carburetor (which they called Minion) was used from about 1980. My 1982 Briggs 92508 has one, unfortunately. Mine hasn't given any trouble, but they were prone to distorting so things didn't fit together well. It's probably a good idea to avoid dismantling them, if you get the choice. The metal versions were more desirable, and more popular, and I think the Minion was discontinued after a few years but I'm not sure.

Ah, there you go. Thanks for that Grumpy, you learn something new every day.

I have seen the two spring setup, but it was on a 2006 engine, like the Pulsa Prime above. Out of curiosity, what engine is it you have there sparker? can you tell us the series of numbers stamped on the cooling cowl?

Grumpy, I believe you nailed it. The "tenants" must have at some point changed the linkage bar. I just happened to have an older style bar that only had provision for the one spring and thought I'd give it a go. The mower purrs like a kitten now instead of screaming its head off. I don't know what the difference is that it made but I'm not complaining - Thanks for your patience. Hi Mr. Davis that's a scary icon you have there - the engine number is 98902 2064 P1 01091954. This place would be lost without you guys or at least I would be. Bad photo's of the two linkages;

Glad you got a result here sparker.

I am a little confused by the engine number, Grumpy, perhaps you could shed some light on this, 09902 seems like a verry small engine to me, maybe it's 89902? or 109902? and the stamp has just misfired?

Or is there a 09902?