150 Optimax blowing fuse help needed

nauti nic · 02 December 2013, 21:08

I bought a speed boat last month to remove the 150 optimax and steering for my boat.Ive been out twice since fitting it and first time started and ran ok but after 30 minutes it stopped dead I managed to get in using my 5 hp aux once on the trailer I removed the hood to see if there was anything that stood out then checked the fuses and noticed one had blown.Once back home changed fuse and it started but sounds a bit rough I noticed some wires in the loom looked bad so got a auto electrician to sort any damaged wires.Used the boat on Sunday started fine put the throttle down and blew the same fuse again I think it's for the fuel pump I put another fuse in and started again and again as soon as I went over 2500rpm it would blow I noticed the voltage was going up to nearly 16 volts so when I dropped the revs to 2000rpm and keep the volts to 14.5 I could keep it running so now I'm not sure if it's the alternator-fuel pump or bad wire somewhere any help would be greatly appreciated

Kernow Buoy · 02 December 2013, 22:11

My 150 Opti was doing something very similar, it had a short in the tilt/trim cable actually inside the throttle lever assembly. This would be particularly relevant if your throttle has been converted to a right hand mounted unit, as new they come left handed and when converted the routing for the cables is poor and they chaff as the throttle moves. The tilt/trim is the same fuse as the high pressure fuel pump!

Portholme · 02 December 2013, 22:22

I had this with a yam control box. It turned out to be the ignition where someone had previously tried to start it with a screw driver, new control box and it stopped blowing fuses.

nauti nic · 02 December 2013, 22:29

Yes the throttle control is right handed how did you manage to narrow it down to the throttle.Steven

Kernow Buoy · 02 December 2013, 22:36

Quote:

Originally Posted by nauti nic

Yes the throttle control is right handed how did you manage to narrow it down to the throttle.Steven

It'd blown 3-4 fuses and as I was trying it ashore with the cover off I actually heard the fuse blow as I tried to tilt the engine. Rob at Black Dog Marine told me that it has happened before with the throttle being converted ( I actually did the conversion and was surprised the cable routing wasn't great) opening up the throttle assemby the chaffed cable was clear to see. Worth a look