HELP yamaha 8 hp cuts out then starts ????

Hi all now i have finally sorted out the pree mix at 50/1 on my 8 hp yamaha it is an old thing in late 80.s i can get the number if need be but it is old <br />ok now the good bit i fired it up after fitting new coils as i bought it needing them it had bn laid up for about a year so was told to make sure that it is pumping water ect <br />it started no problem and the pee hole is pumping water no problem i started it in a big bin with plenty of water in and it ran great for sometime then i went out and put it on my boat it ran great for about 30 or 40 mins no problem then the problem started it would cut out and be hard to start but would start and go for maybe a minute or so then the same again it was still pumping water ect and reving ok just hard to start and would cut out.<br />i had to use elastick bands to get a good seal on the fuel pipe as the round washer typ seal was leaking but it seamd to hold fine <br />it felt to me as tho it was flooding and cutting out i may be wrong can anyone else advise any other thing that would cause it to cut out like that there was no fuel leaks ect even with the elastic band wound around the conection to make a seal and no air was leaking ect from the fuel pipe also just rememberd the vent on the tank was open as i had checked that incase it was under presure <br />thanks all sorry about the long story

Re: HELP yamaha 8 hp cuts out then starts ????

just found out i have a displacment hull so not ment to get on plane would this be causing my engine to bog down and cut out maybe flood cause giving it revs and its not able to push the boat fast enough <br />hope this helps anyone know if this would cause this

Re: HELP yamaha 8 hp cuts out then starts ????

The more I think about this problem the more I think back to the mid-1960's when I had a similar problem. I used a 5hp Johnson to push an old square back canoe when I started having problems like you're having. Drove me nuts for a week trying to find the problem, but an old guy suggested I remove the engine cover and see if it ran okay that way. It ran fine without the cover, but wouldn't run for too long with the cover on. <br /><br />The problem turned out to be an exhaust gas leak from a bad seal in the shaft leg. Exhaust gas leak displaced good air under the cowl, thus killing ignition. Found and replaced the defective seal and life was good again.

Re: HELP yamaha 8 hp cuts out then starts ????

might be worth trying i have changed the plugs today and it revs way way better but havent tryd on the boat again yet come to think of it it was running today with the top on and of and shourly it would do the same in the bin as on the boat if it was exhaust related <br />will try on the boat tho if it dose it again <br /><br />just seamd to happen when under load for a while <br />thanks something to try

Re: HELP yamaha 8 hp cuts out then starts ????

Hopefully plugs do the trick for you.<br /><br />Remember, with a 10' displacement hull you're never going to plane it and, no matter how much power you apply, you'll never go much over 5mph. <br /><br />I'd guess you'll go as fast as you're going to go at about 1/2 throttle, but if you can rig a tiller extension out of something like PVC pipe and sit closer to the middle of the boat it will handle better for you as the bow won't be trying to raise so much and weight distribution will be better.