Yamaha 115 Started Running Rough

[trueblue]

that loose battery terminal will cause horrible running as well.

my 130 konked out once after running rough for a while and it took some time to notice that the battery terminal was loose.

[mustang5]

Yeah I can only think it was a mixture of things that occured in that one moment. I have had the warning buzzer sound before on a previous Yamaha when a wire came loose at the terminal. I can only at a guess think that the jolt caused by the motor dropping revs almost suddenly from WOT, after an extremely rough trip back caused something at the terminals to slightly come loose.

Wierd, but I think I have all bases covered. If it comes on again some time I will quickly get out the temp gun I now have stored in the boat for the next few trips hehe..

Well I gave it a true workout this morning and taking it out again tomorrow (well in 4 hrs) and everything was running perfect. Actually much better than before so I am quite happy and releived.

[ozscott]

The Yam V4 is a seriously good motor...good to hear it is (as always with these motors at least) simple in the end.

Cheers

[trueblue]

Just so you are aware of another hard to find issue that can set the alarm off......

I was getting rough the alarm coming on and going into limp mode once when I would trim the motor while at speed - weird. urned out the battery cable was corroded inside, and was causing a voltage drop due to increased resistance when trimming the motor under load. The voltage drop was enough to upset the motor, go into limp mode, and turn on the alarm.

Changed out the battery cables and all went away - but there was a lot of head scratching for many days of fault finding before we found it, because it wasn't obvious from the outside that the cable was damaged. Turned out that the cable had been cut back years before, and joined to a new end. The join was hidden, so the end looked good but the corroded bit was the old original cable above the join, hidden from view. Didn't identify it until doing a resistance check on the cable.

cheers

Mick