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HELP w/craftsman lawn tractor:no power

966 Views 10 Replies 5 Participants Last post by  gsxr11001990
I have a 4 year old Craftsman lawn tractor, model# 917.289244. It has a 21 HP Briggs, model#331877 type#1371-b1. A month ago, after a no start situation, I diagnosed that the compression release mechanism on the camshaft had failed. I replaced the camshaft. In doing so, I found the pieces to the old one in the sump. most of them were rather small, not much left that was very big! I inspected everything and didn't see any damage from the disintegrated pieces. After putting everything back together, it starts and runs but lacks power. I can put it in gear and it rolls slowly. If I try to engage the blades, it dies. I was wondering if I did something wrong when putting it back together or was there damage I missed. It had enough compression to hold back the starter when there was no compression release. I have spark and I have fuel. I didn't mess with the carb other than to remove it and set it off to the side and then re-install. What am I missing? I guess I'm asking the community what would they look for before throwing their hands up and bringing it to the $shop$! Mower ran well before the no-start issue. It did consume a little oil and I would get some bluish/white smoke when mowing deep wet grass. I figured that was where the oil was going. But I never lost power. Any help would be appreciated. When I do have it running now, I don't have any smoke, but I cant put a load on it, when I do it dies.
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The governor should allow the throttle to open fully. Wide open. To the stop. If not, the engine will not be able to develop full power, and will be limited by how far the governor allows the plate to open.
If you look at the carb linkage, the manual control & cable move a lever with a spring, providing more tension on the spring the farther towards 'fast' you move the control. The governor will attempt to oppose the spring more and more, the higher the rpm. That allows the engine to run with partial load, at the governed rpm(governor arm pulling force fixed by rpm), and when the rpms drop, the governor arm gets weaker, and the spring takes over and opens the throttle to develop more power, similar to pressing harder on the gas pedal while climbing a hill in your road vehicle. On level ground less power is needed, and you back off. Same with the governor, it back off the throttle when the rpms get higher on 'level ground'(sparse grass, not hill climbing), overcoming spring tension.
Either way, check that the throttle can open fully. If not, it needs to be adjusted.
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