main fuse problems....again

[caper_45ca]

I had the opportunity to take my boat for a good run this weekend and the main fuse from the soleniod is blowing again...I had the boat to the dealer here and he replaced the key switch which he said is what was causing the problem...well he was wrong:'(....like i said in a previous post it seems after about 20-30 mins of running this fuse blows and i loose my tach and t&t...but engine runs just fine....I've searched the wiring from stem to stern and cannot find anything that looks like it may cause this problem....what really gets me is that the fuse will not blow right away, it seems to blow over time.....and i cannot find anything that i am doing each time to even give me a clue as to the culprit.....can anyone suggest some way to try and diagnose this problem....forgot to add....1995 johnson 90 hp....mod j90tleor....only has 4 hrs on it since rebuild

 

[caper_45ca]

Re: main fuse problems....again

wow....i was just out looking at my motor and I noticed the little wiring block on the starboard side where all the wires connect.....well upon further inspection I see that the bottom 2 wires are purple.....the next 2 are red on one side and red with blue stripe on other side....next going up is red with blue stripe and red on other side.....then greys and yellows and so on....I am looking in my manual and according to it one of the red with blue stripes needs to be switched.....I didnt do it yet because I am afraid of the results....anyone have any suggestions.....should I switch them....and the thing is when I follow these wires thay go directly to the fuse in question ......

 

[rickdb1boat]

Re: main fuse problems....again

Wonder if the T & T is blowing the fuse....

 

[caper_45ca]

Re: main fuse problems....again

u know I thought that was the problem at first.....but fuse will blow without using t&t......I really believe after the rebuild the dealer reinstalled the wires on this junction bar and they crossed the solid red and the red with the blue stripe...I would like to switch them and try it but am waiting for someone with a bit a savvy around the electrical to give me their opinion......

 

[Barnacle_Bill]

Re: main fuse problems....again

If both wires are going to the fuse, I can't see where that would make a difference unless they are different sizes. Are you sure you are using the right fuse? ie size and type.

 

[rickdb1boat]

Re: main fuse problems....again

If both wires are going to the fuse, I can't see where that would make a difference unless they are different sizes. Are you sure you are using the right fuse? ie size and type.

That's true. And a good point about checking the fuse size....

 

[Seasport]

Re: main fuse problems....again

Well the red is the 12V straight from the battery and the red/purple is the fused 12V from the fuse. Looks like they are reversed which means the unfused 12V is feeding the circuit which is meant to be fed from the fuse and vice versa. I think the 12V to the trim/tilt motor is fed directly from the unfused 12V (via the relays). (The fused 12V feeds the trim/tilt switches which activate the relays) So I think what is happening is that with the crossed wires you are feeding the trim/tilt motor via the fuse which is causing it to blow after a while.

I'd switch those wires around.

 

[Xcusme]

Re: main fuse problems....again

Just a thought....he says that the fuse blows after 20-30 minutes without working the T&T....usually the fuse would blow only if the T&T motors are worked and they are drawing more current than the fuse could hold (since the T&T motors are wired with a fuse and not directly to the Battery)

Frankly, I would measure the current draw on each of the T&T motor leads (up and down feed lines) and fuse the main B+ to the relays too. This would protect the battery from a possible dead short or over current condition from the T&T motors.
I would replace the blown fuse and swing the proper colored wires back to the factory diagram.

Both sides of the T&T system ( relay control side and the T&T load side) would then be isolated and protected.

Since both circuits would then be isolated, it's a simple matter, knowing the Bosch relay coil resistance to compute the current draw of the relays and size the fuse accordingly.

 

[Seasport]

Re: main fuse problems....again

Looking at the wiring diagram I've got here it seems that OMC didn't fuse the supply to the trim/tilt motor. I can't see what else would be drawing enough current to blow the fuse. Maybe the fuse is getting hot with use of the t/t until it finally blows.

 

[caper_45ca]

Re: main fuse problems....again

thank you for all the input......mayb I can be a little clearer....when I first take off in the boat I have to use the T&T...just to gte up on plane and get the boat running at peak rpm then drop bk rpm and hold on plane....sometimes i did usae the T&T but it seemed the fuse did not blow at that time.....anyway just to be a little clearer.....on the wiring block...mine has the red wire matched up to the wire on the opposite side to a red wire with a blue stripe.....and also on this wiring block there are #'s and color codes...on the red coded terminals I have a red wire matched to a red wire with a blue stripe....and on the red with blue cross-hatched terminal I have a red wire matched to a red with a blue stripe wire.....I am thinking the dealer crossed these wires.....this problem did not exist b4 the rebuild....and when i trace these wires .....one is fused...the 20 amp fuse that blows...and the other goes to the solenoid.....if I swirch these 2 wires to try it am I in danger of frying anything?

 

[Xcusme]

Re: main fuse problems....again

Hmmm, the fuse wouldn't blow with no current being drawn across it. I'd still throw an amp meter across the the supply and look for any current flow thru the T&T side when it's not being used. How big is this fuse anyway?? Is the fuse element just melted or is the fuse blackened? Either condition points to either an overload or a short circuit.

Sadly , I don't have a print of the wiring to give any possible solutions.

 

[caper_45ca]

Re: main fuse problems....again

as for the fuse...its a 20amp.about 5/8 inch long......supplied by the dealer.....and never looks blackened just melted off

 

[Barnacle_Bill]

Re: main fuse problems....again

I don't have a diagram for your motor either, but on older models the 20amp fuse comes from the battery side of the solenoid. Now that you explained it a little better, it does sound like they are reversed.

 

[Seasport]

Re: main fuse problems....again

Caper - the wires have been transposed so what should be fused isn't and what shouldn't be fused (trim/tilt motor in particular) is. The red wire will come from the 12V terminal on the solenoid and the red/purple wire will come from the fuse. Both are 12V - just that one has a fuse in it. Swap them over to the way they are supposed to be and I think you'll find the problem goes away.

 

[Seasport]

Re: main fuse problems....again

Someone posted this link to a trim/tilt wiring diagram last week. May be of use.

http://i84.photobucket.com/albums/k33/WILL-JR/Picture.jpg

 

[caper_45ca]

Re: main fuse problems....again

I am going to switch out the two wires in question later this morning (only 6am here).....I will repost and let all of you knopw the results.....thank you all for your input....

 

[caper_45ca]

Re: main fuse problems....again

I swapped the 2 wires and evrything seems to be ok....boat ran fine with no issuesd.....thank you

 

[Barnacle_Bill]

Re: main fuse problems....again

Always like to hear good news.

 

[Seasport]

Re: main fuse problems....again

Good to hear that did the trick - now who swapped them over in the first place?

 

[caper_45ca]

Re: main fuse problems....again

Had to be done at the dealer....they did the rebuild.....I delivered boat and motor...picked it up completed....and get this they diagnosed the problem as a faulty key switch which I bought and replaced at a cost of $50 Cdn....not to mention a round trip of 60 miles to get it.....I havent had a chance to call them yet and tell them of their mistake but rest assured I will be......Thanks again for your help...