bigredscowboy
Chainsaw Amateur
So I'm working on my friends 029 that he bought new in the 90's and has cut about 10 cords per year since then. I measured the compression a while back at 120psi and thought I would do a ring job for him sometime soon. Then he started having this heatsink-ish problem:
It could run for about 30 minutes, add some gas and then 5-10 min later cut off. Not racing like a lean condition. More like kill switch. I thought it was a bad coil. Started fine hours later. I ran it through a tank of gas and on the second tank pinched the blade and it cut off. Wouldn't restart. Choke, half-choke, wide open. Hooked up the inline spark tester and no spark. Problem solved? (see below, tester wire very short) I brought it home and a few days later changed out the spark plug just to make sure before wasting money on a coil. Didn't last more than 5 minutes (with a novice operating it). Wouldn't start. Got out the inline spark tester and made sure that both ends were touching and it sparked great but no run. Now thinking the previous no fire is because the line is so short it won't hold a connection on both ends well (I can barely make the connection). Fiddled, took the air cleaner off, pulled the plug and checked for gas/rich and next pull it started with the inline spark tester and ran fine. Sounded dry and wasn't flinging oil so I cleaned out the oiler and crud at the bar and it oiled fine after that. Put it back together and made certain to get the boot on the plug very well, and it ran nonstop for 30 minutes. I was done with what I needed cut so I headed back to the house. Stopped on the way to cut a stump and couldn't get the thing started. Tried choke, half-choke. Wondering if it was flooded, I pulled the plug and it was dry and white, like it should be. After reinstalling, it started up hard again but eventually ran fine.
What I gather is that I can pull the plug and it will run, but that's not entirely true. Part of me thinks this is a heat-sink coil issue but I don't want to buy a new coil when the old one is firing according to the tester. The other part of me thinks its a low compression problem and I just need to upgrade to the 039/390 jug (already purchased!). Idles well and throttle response is decent so I'm not thinking carb or crankshaft seals. Any diagnostic thoughts other than just replacing the coil?
It could run for about 30 minutes, add some gas and then 5-10 min later cut off. Not racing like a lean condition. More like kill switch. I thought it was a bad coil. Started fine hours later. I ran it through a tank of gas and on the second tank pinched the blade and it cut off. Wouldn't restart. Choke, half-choke, wide open. Hooked up the inline spark tester and no spark. Problem solved? (see below, tester wire very short) I brought it home and a few days later changed out the spark plug just to make sure before wasting money on a coil. Didn't last more than 5 minutes (with a novice operating it). Wouldn't start. Got out the inline spark tester and made sure that both ends were touching and it sparked great but no run. Now thinking the previous no fire is because the line is so short it won't hold a connection on both ends well (I can barely make the connection). Fiddled, took the air cleaner off, pulled the plug and checked for gas/rich and next pull it started with the inline spark tester and ran fine. Sounded dry and wasn't flinging oil so I cleaned out the oiler and crud at the bar and it oiled fine after that. Put it back together and made certain to get the boot on the plug very well, and it ran nonstop for 30 minutes. I was done with what I needed cut so I headed back to the house. Stopped on the way to cut a stump and couldn't get the thing started. Tried choke, half-choke. Wondering if it was flooded, I pulled the plug and it was dry and white, like it should be. After reinstalling, it started up hard again but eventually ran fine.
What I gather is that I can pull the plug and it will run, but that's not entirely true. Part of me thinks this is a heat-sink coil issue but I don't want to buy a new coil when the old one is firing according to the tester. The other part of me thinks its a low compression problem and I just need to upgrade to the 039/390 jug (already purchased!). Idles well and throttle response is decent so I'm not thinking carb or crankshaft seals. Any diagnostic thoughts other than just replacing the coil?
