Johnson 85hp v4 1979 fuse problem!!!

Joined
May 21, 2013
Messages
9
I've recently bought this boat and when I've inspected the fuse I noticed that the previous owner had put tin foil in the fuse holder along with the fuse! I've taken this out and replaced it with a 20amp fuse and now it keeps blowing the fuse!! Can someone please help me!!! The model number is 85ml79r! Thanks in advance!!!
 

emdsapmgr

Supreme Mariner
Joined
Dec 9, 2005
Messages
11,551
Re: Johnson 85hp v4 1979 fuse problem!!!

Check to see what other accessories have been hard-wired into the control box. That 20 amp engine fuse is enough to handle the demands of the engine and a tach. If the prior owner wired the bilge pump, lights, horn and radio to the control box, the circuit is overloaded..
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: Johnson 85hp v4 1979 fuse problem!!!

If no other accessories connected to the control, you are going to have to do some detective work. When does the fuse blow? As soon as you put it in? As soon as you turn the key on? As soon as you operate the push-to-choke? As soon as you turn the key to start? Or perhaps the overheat horn is shorted. That is about all the items that the fuse supplies. Of course, some genius may have done some wire swapping. That makes things interesting.
 
Joined
May 21, 2013
Messages
9
Re: Johnson 85hp v4 1979 fuse problem!!!

Hi, thanks for the reply!

I start the engine and it runs fine, then I'll turn it off and start it again and still no problems, but then after a few times if starting it the fuse blows! The is no accessories on this circuit as the bilge, horn etc are connected to a different battery. If I put the tin foil back in the boat starts every time! Do you think a bigger fuse might solve it? I don't fancy paying out for any new parts until I find out what's causing it! Do you think it could be the starter motor? I'm sure the fuse blows as you turn the key, ie without the engine starting up. I'm out on the boat this weekend and this could halt me going out!

Thanks again
Graeme
 

Numlaar

Chief Petty Officer
Joined
Jul 9, 2009
Messages
633
Re: Johnson 85hp v4 1979 fuse problem!!!

Putting in a bigger fuse (or using tinfoil) is not "solving" the problem, that is a very poor bandaid at best. By doing so, you are defeating the purpose of the fuse. If the circuit has too much load on it, the wires heat up, which could result in a few bad scenarios (melted harness, electrical fire, etc.). They are there for a reason.

I would follow the advice given, and start to track down the issue and isolate it. If it doesnt blow consistently, and immediately its not a dead short, but from the symptoms it sounds like it could be close to it. I would also look for any exposed wires that may be grounding out, loose connectors, etc.. Make sure you have all of the clips that hold the connectors together in place as well. Good luck!
 
Joined
May 21, 2013
Messages
9
Re: Johnson 85hp v4 1979 fuse problem!!!

Thanks!

I will search tonight to find the problem! Is it safe to use the boat this weekend if I just replace the fuse with a 20amp fuse when it blows?
 
Joined
May 21, 2013
Messages
9
Re: Johnson 85hp v4 1979 fuse problem!!!

Well I've just spent two hours searching for faults!! I took off the key ignition and accelerator cable and I've found a bare wire!!!! It was touching another wire that was now all melted!! Going to tape them all up and make sure they aren't touching then fingers crossed it solves the fuse!!!!
 

F_R

Supreme Mariner
Joined
Jul 7, 2006
Messages
28,195
Re: Johnson 85hp v4 1979 fuse problem!!!

Sounds like you did good.
 
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