I thought I'd reach out here before I pull the trigger on a expensive part. In general I'm pretty good with these things, but this one has me wondering. Last year I was ripping around on the dinghy with a 05 Yamaha F4 and it randomly quit after years of working perfect. Wouldn't restart. Row back to the big boat. Pretty sure I remember trying it the next day and it ran. Ok, maybe the carb barfed. Anyways, take it on another trip, won't even start. Take it home, put a compression tester on it, 0 psi. What?? 0? Did I blow a hole in the piston how is this even possible? Take the head apart, stuck exhaust valve open. Ah ok, explains the 0psi. Why is it stuck? I read it could be because the valve leaks and allows oil on it that burns and makes it sticky. Ok, check the valve spec, it's good, replace the valve seal in the head, put it back together. Test it, runs awesome, great.
Out on another trip, quits randomly again. WTF? the valve again? Nope compression is good. Wait a while and fires right up like nothing is wrong and runs perfect. Again quits randomly, notice gas pissing out of carb this time. Ah ok, the float needle is done and is flooding the carb, explains random failure. Replace that. Test again, bring the carb to pressure with the bulb to make sure it hold tight, perfect. Out on the water, runs perfect WOT for 15 minutes, then as I slow down I notice it wants to stall so I bring it back to WOT slowly but after a minute, it then dies suddenly like you turned it off.
Row back to shore, try it at the dock, fires right up again, like nothing is wrong. Ok... Must be the coil pack overheating... ? It's not the carb and it's not vapour lock, it happens at idle too, I have thoroughly vetted it, cleaned it numerous times and the fuel pump pumps like a champ I verified this numerous times while it was running.
The TDI unit is $$$ and not returnable. Before I replace it I thought I'd check to see if anyone has run into this before. I've seen similar issues with overheating coil packs on other units before. Only other thing I could see is that dang valve still sticks sometimes but then pops back in and it starts again. Seems highly unlikely and the coil seems more likely. Kill switch is fine I even disconnected it to see if it made a difference, it didn't. I did do a spark check immediately after the failure on the water and it was hard to tell in broad dailight on the water but there was a spark I think, it looked weak though.
Long story I know but you need context to weigh in. Welcoming some feedback, this one has me scratching my head. Thanks.
Out on another trip, quits randomly again. WTF? the valve again? Nope compression is good. Wait a while and fires right up like nothing is wrong and runs perfect. Again quits randomly, notice gas pissing out of carb this time. Ah ok, the float needle is done and is flooding the carb, explains random failure. Replace that. Test again, bring the carb to pressure with the bulb to make sure it hold tight, perfect. Out on the water, runs perfect WOT for 15 minutes, then as I slow down I notice it wants to stall so I bring it back to WOT slowly but after a minute, it then dies suddenly like you turned it off.
Row back to shore, try it at the dock, fires right up again, like nothing is wrong. Ok... Must be the coil pack overheating... ? It's not the carb and it's not vapour lock, it happens at idle too, I have thoroughly vetted it, cleaned it numerous times and the fuel pump pumps like a champ I verified this numerous times while it was running.
The TDI unit is $$$ and not returnable. Before I replace it I thought I'd check to see if anyone has run into this before. I've seen similar issues with overheating coil packs on other units before. Only other thing I could see is that dang valve still sticks sometimes but then pops back in and it starts again. Seems highly unlikely and the coil seems more likely. Kill switch is fine I even disconnected it to see if it made a difference, it didn't. I did do a spark check immediately after the failure on the water and it was hard to tell in broad dailight on the water but there was a spark I think, it looked weak though.
Long story I know but you need context to weigh in. Welcoming some feedback, this one has me scratching my head. Thanks.