OutdoorKing Repair Forum Forums Repairs and Maintenance Questions on Engines Questions On Briggs & Stratton Engines 5hp B & S Governor question.

I am repairing my 5 hp mulcher engine 133432 1041E1 990107YA which had developed some loose parts around the throttle assembly area. It became apparent when the engine would only operate at very high revs, perhaps too high, no matter where the throttle was positioned.
I found that if I manually moved the governor arm to the left then the revs would decrease but the lever does not move that way of its own accord when the throttle is reduced. This model does not have a return spring so what should be making the governor lever move towards the idle setting?

Hi Husky888 and a warm welcome to the forum.
It sounds as if your governor has packed up. The illustrated parts list shows 2 springs, one being the governor link spring which goes around the governor link rod, which connects the carby to the governor and the other being the governor spring which i have highlighted with a green in the image below.
Having said that the absence of the governor spring should not make your engine over-rev, in fact it should retard the throttle to idle, if the governor itself is working correctly. The role of the governor is to close throttle, the governor spring in turn opens throttle relative to the tension on the spring. i.e. move throttle lever to full revs, more tension on the spring, move throttle lever to idle position, less tension on the spring.
To check if the governor is functioning correctly, start the engine and move the governor lever so as the engine idles. if you let it go manifold vacuum will move the carby butterfly to the more favourable open position. You should feel a considerable amount of resistance on the linkage as you move it to the full throttle position(i.e. it should be pushing back to the idle position). I'm guessing you will feel no real resistance hence leading me to believe the governor has failed.

Your governor gear part number is 494845 and has been discontinued, but there is 1 US based ebay seller who has 2 NOS ones available.

Wouldn't hurt to check the static governor adjustment since there where loose parts before writing the governor gear off.

If you have been repairing it, is it possible you have at some stage loosened the governor lock bolt?, the nut just to the bottom left of green square bigted has highlighted? The governor arm should be set hard one way using a screwdriver in the slot on it and locked by that nut otherwise it will rev out regardless of throttle setting.

Thank you for your replies. I fully understand it now. Previously I couldn't see why most engines have a governor return to idle spring but this model doesn't. It is in pieces at the moment - the governor looks to be in good condition -so I will report back when it is back together.

This engine is all repaired now. The governor fault was caused by the loose throttle assembly - it could only move a few millimetres but it was enough to put tension on the governor spring so that the governor lever would not return to idle. Also the muffler was very close to the arm and might have been touching it.
It has been a very interesting learning experience for an amateur mechanic and the engine looks to be in very good shape now.
Thank you for your expert advice.

Well done husky888.
I will close this thread now and if anyone wishes to add to it please PM a moderator