Nearly a week ago I had a few posts about a swather that would run okay until it warmed up, at which time it would sputter and barely run. I went through most of the electrical system, thinking a bad coil was the culprit. Further complicating things, someone else put a different coil on it than what it came with. Anyway, after verifying that the spark-maker was all correct, I suspected the fuel system. Cutting oats Monday, I ran about 45 minutes with no problems. Then I started to hear a little chugging, and after a couple more rounds it died. I restarted it 25 minutes later, and a half round later it acted up again. I pulled out the choke a little and it evened out enough to finish up the field and get home. During this time, there were little air bubbles in the fuel pump sediment bowl. Upon closer inspection at home, the elbow fitting on the suction side was quite loose. So here is my take on it:
The fitting leaked air into the fuel pump all the while, but did not lean out the mixture enough to really hurt so long as the rig was fairly cool. When warmed up good and working hard, this leanness in mixture was enough to be a problem. Choking it cut the air just enough to make it run. I replaced the fuel pump about eight years ago, and with the metal lines, one can only tighten the elbow fittings so far and still have them line up. Over time, this little bit of slack in the threads vibrated its way into a lot of slack (brass and aluminum threads wore) and this created the leak. I permatexed the threads and tightened them up as much as I dared, and it seems to start better and run pretty well now (It should, as nearly everything else has been looked over quite closely!). So anyway, I Thank You all for your good input. This forum is a great place to learn.
Lon M in NE South Dakota
The fitting leaked air into the fuel pump all the while, but did not lean out the mixture enough to really hurt so long as the rig was fairly cool. When warmed up good and working hard, this leanness in mixture was enough to be a problem. Choking it cut the air just enough to make it run. I replaced the fuel pump about eight years ago, and with the metal lines, one can only tighten the elbow fittings so far and still have them line up. Over time, this little bit of slack in the threads vibrated its way into a lot of slack (brass and aluminum threads wore) and this created the leak. I permatexed the threads and tightened them up as much as I dared, and it seems to start better and run pretty well now (It should, as nearly everything else has been looked over quite closely!). So anyway, I Thank You all for your good input. This forum is a great place to learn.
Lon M in NE South Dakota
