F8 stalling second opinion

ashedd

Petty Officer 2nd Class
Joined
Jun 16, 2015
Messages
175
Hi, so I used my new to me 2011(ish) F8 today for the first time. Got it started, it wouldn't really do a low idle without pulling the choke to keep it running. So I figured it needed the idle jet cleaned out, but after some high idling it ran ok at low idle. It has tons of power and will throw you out of my 11' walkerbay RIB in a heartbeat.

After my little sea trials around m y dock I decide it's time to go out and give it a real test. It runs great at first, easily planes the RIB. then all of a sudden it dies(after about 7-8 mins). I restart it and it'll idle real slow but die if you give it any gas. I checked fuel connections, fuel bulb(hard), confirmed the fuel pump was pumping and still nothing. It would start with a low idle and die after a few seconds. At this point I'm thinking it needs a carb rebuild. But then it stopped starting.. so I try starting fluid and nothing. Try choke, nothing. Didn't really have the tools on board to pull a spark plug. But I did try to ground a screwdriver from a plug boot and saw no spark. I also looking at the kill switch closely. So I tilt it all the way up and start paddling, fighting the wind. I only had a kayak paddle but it worked ok while standing.

After about 20 mins of paddling I decide to give it another try. Lowered it, choked it, no start. Did away with the choke and it started after several pulls. Gave it a few revs and it idles down fine. I didn't waste and time, I threw it in gear and high tailed it home, which was only about a 1/4 mile away. Got back to the dock and it's still running fine.

SO... I'm thinking it may need an ignition module. I figure it stopped working when it got warm and eventually stopped working altogether. Once it cooled down really good then it started working again. I say ignition module because it did start and idle at first and then wouldn't start, even with starting fluid. Air temp was around 49F.

But I could also see how a sticking float could do something similar, but again, it wouldn't start with starting fluid.
 

charleso

Petty Officer 2nd Class
Joined
Nov 13, 2006
Messages
179
Could indeed be electrical. But also could be fuel/tune up related. Sucked water from fuel tank into cylinder. Starting fluid evaporated and took water with it, allowing the plug to fire properly.
 

ashedd

Petty Officer 2nd Class
Joined
Jun 16, 2015
Messages
175
Fuel supply would be my first thought... however it's a brand new yamaha tank and hose.. Today was the first time it's had fuel in it.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Check the fuse, they can get a little corrosion on them and not make good contact.
 

ashedd

Petty Officer 2nd Class
Joined
Jun 16, 2015
Messages
175
Waiting on my coil to arrive. I'm going to try and clean the idle circuit in the carb without removing it, I've read how that should be possible by removing the idle air mixture screw and spraying carb cleaner in there. It also occurred to me that maybe the motor overheated and shut down? I find that scenario unlikely because I would have noticed that, plus I'm not even sure the F8 even has the capacity ti shut itself off when it gets too hot. I don't know how sophisticated the ecu it. I may have to just face the fact that I need to remove the carb and clean it.
 

ondarvr

Supreme Mariner
Joined
Apr 6, 2005
Messages
11,527
Removing the carb and cleaning it is very easy, don't stress over it. Spraying carb cleaner into the low speed adjustment screw hole has a slight chance of working, but is nothing like cleaning the carb. These motors are very susceptible to plugged low speed jets, it's one of the major complaints, so get used to cleaning it.
 

ashedd

Petty Officer 2nd Class
Joined
Jun 16, 2015
Messages
175
I've done it a million times, I just don't really want to do it. Plus it's in the water and I'm not lugging that thing up and out just to take the carb off. So I have to go very slow so I don't drop anything overboard. I've dropped stuff before but the waters too cold to go get it right now. Unless I can snag a carb with a grappling hook lol
 

ashedd

Petty Officer 2nd Class
Joined
Jun 16, 2015
Messages
175
carb cleaner helped a tad, but I guess the carb is coming off
 
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