Ibeatgodzilla
ArboristSite Lurker
Hi all,
I had a pretty odd problem on my FS450 the other day - as a general rule, my most reliable piece of kit.
Got a full tank's work done, as usual, stopped when needing refueling, then it didn't want to start again. It popped once or twice but didn't want to actually run - it's never done that before, and I do use it a lot, all year round. So, I bring it into the shed and see what's up (once it had cooled down). Upon removing the plug boot, the boot decided it didn't want to hang on to the HT lead any more and appeared to be quite corroded inside. OK, so there's the problem - bad HT lead, no spark. Thankfully I'd ordered a spare coil with some other parts in foresight a while back, and thought it easier to change the whole unit.
New coil on; won't start, no spark. Eh? Why could this be? It only stopped running because it had run out of juice; no issues during use. Bad coil? Possibly? So, I put the original back on after having unscrewed the HT lead and plug boot from the new one and transferred it to the original. Still no spark. What? But... It was running just fine! I'm not sure what made me try it, but I removed the spade connector from the coil which goes to the kill switch circuit... And lo and behold, spark - it was fine after that!
However that spade connector is a normal part of the circuit, it's supposed to be connected, as it was when I first went to remove the coil (again, it was running fine during use just minutes prior!)
How very odd that something in the kill switch circuit had failed at the exact same time as I ran out of fuel. My only theory is that it was a hot day, doing tough work, and as soon as it ran out of fuel, engine stopped, no more fan to cool the engine, and something melted causing a short circuit (?). However I can't see what or where. And I do use it regularly, intensive work not infrequent, and it never seems to have any particular overheating issues. All is fine inside the handlebar control (no surprise; why wouldn't it be?) and the little spade connector that's supposed to go to the coil can be seen going along the outside of the crankcase and screwed into an earth point later on, nothing appears bad with it except it's somehow shorting the coil and stopping it from sparking. There weren't any insulator washers on the coil that may have been forgotten upon reassembly. The coil is screwed directly to the casing, metal to metal.
For now, rather than choking it which results in far more petrol than I'd have imagined flooding the system and making a mess of the air filter and the floor, I'm going to make a second kill switch by putting the spade connector to the outside of the casing (it does reach), and having a second little wire from the coil to the outside with a switch between them. Not the most convenient, but it'll work.
However admittedly I'm a little stumped at what's causing the issue here, and why when connected 'properly' the coil is permanently being given the kill engine signal; there is definitely no short within the control handle when in the 'on' position.
I had a pretty odd problem on my FS450 the other day - as a general rule, my most reliable piece of kit.
Got a full tank's work done, as usual, stopped when needing refueling, then it didn't want to start again. It popped once or twice but didn't want to actually run - it's never done that before, and I do use it a lot, all year round. So, I bring it into the shed and see what's up (once it had cooled down). Upon removing the plug boot, the boot decided it didn't want to hang on to the HT lead any more and appeared to be quite corroded inside. OK, so there's the problem - bad HT lead, no spark. Thankfully I'd ordered a spare coil with some other parts in foresight a while back, and thought it easier to change the whole unit.
New coil on; won't start, no spark. Eh? Why could this be? It only stopped running because it had run out of juice; no issues during use. Bad coil? Possibly? So, I put the original back on after having unscrewed the HT lead and plug boot from the new one and transferred it to the original. Still no spark. What? But... It was running just fine! I'm not sure what made me try it, but I removed the spade connector from the coil which goes to the kill switch circuit... And lo and behold, spark - it was fine after that!
However that spade connector is a normal part of the circuit, it's supposed to be connected, as it was when I first went to remove the coil (again, it was running fine during use just minutes prior!)
How very odd that something in the kill switch circuit had failed at the exact same time as I ran out of fuel. My only theory is that it was a hot day, doing tough work, and as soon as it ran out of fuel, engine stopped, no more fan to cool the engine, and something melted causing a short circuit (?). However I can't see what or where. And I do use it regularly, intensive work not infrequent, and it never seems to have any particular overheating issues. All is fine inside the handlebar control (no surprise; why wouldn't it be?) and the little spade connector that's supposed to go to the coil can be seen going along the outside of the crankcase and screwed into an earth point later on, nothing appears bad with it except it's somehow shorting the coil and stopping it from sparking. There weren't any insulator washers on the coil that may have been forgotten upon reassembly. The coil is screwed directly to the casing, metal to metal.
For now, rather than choking it which results in far more petrol than I'd have imagined flooding the system and making a mess of the air filter and the floor, I'm going to make a second kill switch by putting the spade connector to the outside of the casing (it does reach), and having a second little wire from the coil to the outside with a switch between them. Not the most convenient, but it'll work.
However admittedly I'm a little stumped at what's causing the issue here, and why when connected 'properly' the coil is permanently being given the kill engine signal; there is definitely no short within the control handle when in the 'on' position.
