Hi all; I thought I'd throw this out here to see if someone has experienced the same and found a fix. It's to do with my 2003 F115 Yamaha. It recently started some electrical gremlins - when running fast it has occasional cut-outs. For a split second the motor cuts out to return to full and smooth operation until the next episode of the same. Sometimes I can run for half a day without it and sometimes it comes every few seconds. Very unpredictable and uncomfortable. I went through the entire fuel system - even replaced all injectors. It's not the fuel system - when it runs it runs beautifully and smooth with no hickups or hesitations, always starts fine. The one thing that I was able to track down is that it may be some kind of electrical interference from the trim system. Not always but quite a few times I was able to trigger such episode by trimming the motor when running. Anyone any ideas?
F115 Issues
- Thread starter chris73
- Start date
ReelSlim
Crew Member
I had an issue with a 2008 F150 cutting out at times. Checked every electrical connection and was ready to send it to the shop. I came across a similar issue on another forum. It ended up being the factory ground on the motor itself. It was painted at factory and looked 100%. When I unscrewed it it was dry and powdery. I cleaned up the threads and tightened it back down and issue solved. Worth a try for the time it takes.
Check the grounds on the coils and also the continuity of the spark plug boots. Th first thing to check are the small end caps on the spark plugs if your engine uses plugs with them. I've had the same issue and found that new NGK plugs had loose end caps that caused the miss. Tightened them all up and it went away. An intermittent electrical miss can be a ***** to pin down as it will never act up when you have it under a microscope or in the shop.
Last edited:
Interesting! Is that where the battery negative cable attaches to the block (at the starter)? Or do you mean another ground connection?
Thanks, Rollie, I will check this too - simple enough.
ReelSlim
Crew Member
Mine was where it attached to the block. Looked perfect like from factory but once the threads were loosened it had signs of some corrosion or galvanic reaction and left a very dry powder on the threads.
I have read a few more reports on the THT forum as well and seems to be fairly common.
Rollie, is the coil ground through the mounting bolts into the block? Don't see any ground wires on the coil assemblies.
Mine have ground wires on the 2 stroke..but I also sand the mounting surface for the coil to make sure it is clean as well. But check the spark plug end caps that they are tight. Simple thing and with mine will cause a miss. Happened on 2nd trip to Port Angeles last year helping Steve Nelson deliver a boat....he noticed it was loose as I was about to replace a coil.
Similar threads
