[pmakki]

2005 pony-779 stalls when pto is engaged. 42' cut, B&S 17.5hp any solutions? Not used much because always something wrong with it. This is my current problem. New oil change, air filter is clean.

 

[Mark / Ohio]

If it drives and runs fine until the PTO is engaged I would checkout the reverse mowing cutout switches and wiring. Maybe for some reason it thinks it is in reverse all the time.

Is there a switch that has to be pushed or the blades shut down to backup without killing the engine?

 

[pmakki]

Hi Mark, thanks for the response, there is a button to press on the dash to mow in reverse, have never used it though. It runs and drives fine, until pto is engaged. Then sputters and quits. How would I go about testing or bypassing thgis system?

 

[Mark / Ohio]

Out of curiosity you might try pushing (maybe holding) the button and then try engaging the pto and see if it stays running. As for testing or bypassing that varies from one model to the next. We avoid discussing specifics on bypassing safety switches here for legal reasons. But it's a pretty basic circuit normally with switches that are either normally open or closed (short) actuated by the linkage to the reverse pedal or when the shift lever is placed in the reverse gear (depending on the type of transmission you have.)

Normally a safety switch issue will cause the engine to shutdown with no sputtering. I suppose you could have a bare wire partly shorted to the frame or a partly shorted or open switch. But if the carb is out of adjustment, especially on the lean side that could also cause a stall under load. Does it throttle up from an idle smoothly without hesitation? If you load the engine say by pulling a heavy cart uphill can you hear the governor kick in without hesitation to maintain the engine speed under the load?

Another thought might be to check that your mower deck (assuming that is what your pto is currently driving) does not have a seized up bearing or something jamming up the blades or belts such as a tree limb in the belt path or caught between the belt and one of the pulleys.

 

[ddog]

Out of curiosity you might try pushing (maybe holding) the button and then try engaging the pto and see if it stays running. As for testing or bypassing that varies from one model to the next. We avoid discussing specifics on bypassing safety switches here for legal reasons. But it's a pretty basic circuit normally with switches that are either normally open or closed (short) actuated by the linkage to the reverse pedal or when the shift lever is placed in the reverse gear (depending on the type of transmission you have.)

Normally a safety switch issue will cause the engine to shutdown with no sputtering. I suppose you could have a bare wire partly shorted to the frame or a partly shorted or open switch. But if the carb is out of adjustment, especially on the lean side that could also cause a stall under load. Does it throttle up from an idle smoothly without hesitation? If you load the engine say by pulling a heavy cart uphill can you hear the governor kick in without hesitation to maintain the engine speed under the load?

Another thought might be to check that your mower deck (assuming that is what your pto is currently driving) does not have a seized up bearing or something jamming up the blades or belts such as a tree limb in the belt path or caught between the belt and one of the pulleys.

I didn't see anyone mention that there possibly is a safety switch on the seat. They are generally normally closed so the engine won't run until pressure on the seat opens it.
Look for a switch like this and see if you have one that is messed up.

 

[MNGB]

As ddog posted I'd check the seat switch, also on my Husqvarna had that problem the switch looked like it was connected and when pushed together the engine would run great but after some time would not run when the clutch was engaged after much discussion between me and the mower I discovered that the switch connector would wiggle ever so little bit out and would shut the engine down put a small zip tie on it about 3 yrs ago and its never bothered again.
GB in MN

 

[TC]

pmakki
If the mower starts and runs smoothly without the PTO trying to turn the blades I would bet the safety switches are O.K. They usually will not allow the mower to start or in the case of the reverse safety switch, it would sound exactly like you turned the key to the off position. They are simply grounding out the engine. I would look at the deck, deck belts and the spindles. Also look at the blade brakes. It sounds to me as if everything is working just fine until you put a "real load" on the engine and it stalls. My guess is that you'll find the problem somewhere in the deck area. Good luck.