I'm gonna blow a Fuse!!!

andreworiordan · 27 April 2011, 18:39

Hi all, I have a 90hp 4 stroke Mercury engine, the year is 2004. over the last two weeks It has been blowing the 20amp fuse in my engine, I would be driving away and and it will blow, I have checked the cables in the engine looking for a short circuit but cant find anything obvious, it sometimes blows when i'm tilting the engine and today I noticed that it just blew, didn't even touch the tilt which makes me think its not a problem with the tilt switch, it goes at random time, She might run all day then blow when i'm tilting the engine up, then the next day it might blow 3 fuses and then be fine, any ideas?

When it does blow I loose my trim, my Rev gauge freezes and if i try start the engine it obviously has no power so it does nothing

Any help would be great, I was hoping to be up and running doing tours this weekend but this is making me very nervous bringing paying passengers out on my boat.

Thanks Guys

andreworiordan · 27 April 2011, 18:45

The Engine in Question

Jeff · 27 April 2011, 19:03

Worth checking the wiring from the throttle box up into the handle - often chafe around the pivot

Chris · 27 April 2011, 19:11

its going to be chafed wires somewhere, water in something start at the control box and work you way back.

you can disconnect things and run it for a while to see it the problem stops. e.g. the trim. Try disconnecting at the control box and run without it for a while. Then try disconecting at the engine harness.

andreworiordan · 27 April 2011, 19:12

will have a look at that tomorrow, whats strange is how random it blows, i'm gonna make a full list of what might be causing a short circuit and go through everything i can, i was thinking of disconnecting the wiring loom and tilt up/down and see if it blows, if it does i can rule out the controls, next maybe disconnect the tilt switch on the engine, I was talking to a few people and they mentioned maybe a damaged magneto?

Boats&Outboards · 27 April 2011, 19:20

Quote:

Originally Posted by andreworiordan

will have a look at that tomorrow, whats strange is how random it blows, i'm gonna make a full list of what might be causing a short circuit and go through everything i can, i was thinking of disconnecting the wiring loom and tilt up/down and see if it blows, if it does i can rule out the controls, next maybe disconnect the tilt switch on the engine, I was talking to a few people and they mentioned maybe a damaged magneto?

They wernt engineers by any chance.....pardon my scepticism

Start with the wiring, it's got to be something silly to be so random

Peter ~ askboatsandoutboards4sale@sky.com ~ 07930 421007

andreworiordan · 27 April 2011, 19:47

is it happens I was talking to a marine engineer, he is a pure legend of a man!

So i guess its a case of looking at every bit of wiring on the engine, could it be anything to do with the motor in the tilt unit itself, There is a bit of rust on the motor case itself and makes a louder noise when tilting the engine down.

also will need to have a look at switches to see if there is any water getting in there

Justribing · 27 April 2011, 20:18

It may be worth getting someone to megger the motor for you if it has water in or a short it could cause this.

Is there anything thats tight, in other words is something drawing to much current or is something maybe shorting. Same result blown fuse different causes.