oldtin 0 #1 Posted June 16, 2011 :hide: I have a 79 C121 with a 301AQS that bogs down when I engage the mower. I have installed a NOS carb, a new coil and condenser,rebuilt the fuel pump and regapped the points. My problem is that when I engage the mower clutch the engine bogs down and wants to stall. if I disengage the clutch the engine pics up rpms and seems to run fine till I engage the clutch for the mower again. I also replaced all the fuel line and a new filter. Help, I'm stumped! Share this post Link to post Share on other sites
shorts 182 #2 Posted June 16, 2011 If the engine runs good and the tractor drives like it should, is the deck ok, are the blades and spindles free to spin, do the mule drive pulleys turn freely? :hide: Share this post Link to post Share on other sites
rmaynard 15,519 #3 Posted June 16, 2011 I think "shorts" has hit the nail on the head. If the engine runs fine without the mower engaged, but bogs down when engaged, it's not the engine, it's the mower or the mule drive. Share this post Link to post Share on other sites
oldtin 0 #4 Posted June 17, 2011 Both deck and mule drive spin free!! Share this post Link to post Share on other sites
gwest_ca-(File Mod) 11,060 #5 Posted June 17, 2011 Check to make sure you have consistent battery voltage at the (+) side of the ignition coil. The ignition is powered by the pto switch with the pto OFF. The ignition is powered by the seat switch with the pto ON. May be a problem with the seat switch or the wiring to or from it. To check the seat switch remove the connector and add a temporary jumper to the 2 wires in the harness and try it. Garry Share this post Link to post Share on other sites
rmaynard 15,519 #6 Posted June 17, 2011 Check the governor for proper operation. Share this post Link to post Share on other sites
oldtin 0 #8 Posted June 17, 2011 Bogs,but will die if I don't disengage the mower! Share this post Link to post Share on other sites
TT-(Moderator) 1,131 #9 Posted June 17, 2011 Remove the mower drive belt from the PTO & then try engaging it. Share this post Link to post Share on other sites
oldtin 0 #10 Posted June 17, 2011 Removed the belt and it still seems like it isn't coming up to speed as before! Seems to get worse today as it gets hotter! Share this post Link to post Share on other sites
Don1977 604 #11 Posted June 19, 2011 How fast do you have the engine when you engage the mower? Share this post Link to post Share on other sites
rmaynard 15,519 #13 Posted June 20, 2011 Do you know how to post pictures on the forum? Do you have a camera that can take a video? Can you video the tractors problem and post it here for us to see? Share this post Link to post Share on other sites
Kilroy 0 #14 Posted June 20, 2011 Check the governor for proper operation. This worked in my application, 78 C-121. I moved the spring up a few holes to increase governor sensitivity and it solved the dropped RPMs when the PTO was engaged. I would start there, and if that doesn't work check your spark plug, then points, then check the carb. If you get to the carb, might be worth your trouble to get a carb kit and clean her out and freshen her up. Start with the easy/free stuff and go from there. Share this post Link to post Share on other sites
oldtin 0 #15 Posted June 21, 2011 Today I got a new Kohler plastic fuel pump and a carb kit fron Napa. Put on the pump and it sure pumps alot better but did not solve the problem. Tomorrow I will rebuild the original carb and put it on an see if it helps!! Share this post Link to post Share on other sites
Save Old Iron 1,566 #16 Posted June 21, 2011 how about the issue not being mechanical maybe electrical somehow the safety switches are seeing you "off the seat" and killing the engine when the PTO is engaged. If this is coil based ignition, TEMPORARILY jumper the + side of the ignition coil directly to the battery. Sit in the seat, start the engine and try to engage the PTO. What happens :hide: Share this post Link to post Share on other sites
oldtin 0 #17 Posted June 22, 2011 I'll try the jumper wire tonite. Share this post Link to post Share on other sites
shorts 182 #18 Posted June 23, 2011 location,location,location where are you located so that someone close by may be able to give you a helping hand in person Share this post Link to post Share on other sites
oldtin 0 #19 Posted June 24, 2011 Western Pennsylvania,north west of Pittsburgh! Share this post Link to post Share on other sites
Butch 194 #20 Posted June 24, 2011 My C-85 does the same thing. When I engage the PTO the tractor wants to stall and I have to disengage the PTO or it will stall. It takes several attempts to get the mower engaged without it stalling. I've just learned to live with it and take my time engaging it. 1 Share this post Link to post Share on other sites
wheeledhorseman 574 #21 Posted June 24, 2011 I've had a similar sort of problem with my C-120 auto that I've just about finished restoring. I didn't do much to the engine on the basis that it may not be broke so don't try fixing it. I got a deck to fit on it and tried it out. It seemed ok until the tractor had to go up hill as well as power the deck then it started to bog down even at full throttle. Disingaging the pto made the engine pick up again and she'd mow a bit more till going up hill again. On the basis that the engine was only able to produce the power required at good revs, and then only up to a limit, I followed a different line of investigation. Took the head off and discovered it had been blowing at one point on the gasket though not enough to have burnt through or give a visual clue externally. Took the valves out and discovered that the exhaust was a bit burnt as well. Basically, there was enough power for the tractor to drive about and do light work but under full load the effects of the head gasket and valve meant there simply wasn't the power to do it. Could be worth checking out if all else fails. Share this post Link to post Share on other sites
oldtin 0 #22 Posted June 24, 2011 Western Pennsylvania,north west of Pittsburgh! Share this post Link to post Share on other sites
shorts 182 #23 Posted June 25, 2011 It sounds like you have the fuel system under control, did you run a compression test? check the points and condendor? governor linkage adjustment? is the throttle free to move wide open when the governor asks it to? are you using fresh fuel? Share this post Link to post Share on other sites
oldtin 0 #24 Posted June 29, 2011 Time for an update,checked the wiring and found the rectifier had burnt off a connecter inside the box,so I replaced that. Took and removed the NOS carb and rebuilt the stock carb and installed it. Adjusted the govenor linkage and checked the points. Runs somewhat better,but still wants to stall when I cut about 20 feet of grass. It seems to me the engine is running hotter and it seems like the exaust sound is barking!! Backfires when I start to decrease the throttle. This has got me at wits end.plowed snow great all winter now with the deck on it doesn't want to run properly!! :woohoo: Share this post Link to post Share on other sites
tunahead72 2,424 #25 Posted June 29, 2011 Is it possible your PTO clutch is too tight? :woohoo: Share this post Link to post Share on other sites
