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BF50 carb'd Ignition Fuse Keeps Blowing

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Pathfinder22

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Out of the blue my Honda 50 (2007 BF50, carb'd) wouldn't turn over and the power trim & tilt stopped working at same time. I checked the 10 amp fuse under cowling and it was blown. I changed and motor would start and PT&T work until everytime I restarted and then same issue occurs...

Took to local honda shop/dealer and got $913 bill for:
- annual service; which I requested...
- water pump/impellor & thermastat replacement; which I requested...
- lenco trim tab tactile switch replacement; which I just replaced myself and wasn't expecting...
- troubleshooting & fix of blown fuse issue....which they said was replacment of wiring harness, incl key/ignition switch; WHICH I WASN'T EXPECTING and WAS SHOCKED THEY SAID WAS THE ISSUE...

Not only was this more expensive than annual service cost on my Yamaha 200 VMAX/HPDI, it turns out the problem wasn't fixed...very frustrating!!!

Took boat out this weekend after picking up and same shi7 occurs: start, hit the throttle and go to use trim & tilt switch on binnacle and PT&T doesn't work...and after turning off the motor, it doesn't start due to blowing 10amp fuse under cowling in front of starter. Took back to dealer to fix and the could not duplicate the issue. They advised me they traced everything along the "new wiring harness" they installed as the initial fix AND checked all connections and started everyday or several times per day over the past 7 days...and no blown fuse.

PLEASE HELP
 
One more thing that is a known, which is the factory Honda analog tach went on the blink 6-8 months ago and I never bothered replacing since I don't really use. The motor ran fine, so I'm assuming this blown fuse issue has nothing to do with the tach not working -- is my assumption incorrect??

Can I simple disconnect the tach all-together since I want to permanently remove the tach anyways...and not have to worry??

THANKS!!
 
Yes,the tach could be blowing the fuse. Just disconnect it and insulate the ends of the wires.

When does the fuse blow? When you start the motor? Or when you trim the motor and you have it in forward gear?


One more question.....does you boat have a metal hull?

Mike
 
Now that I wrote that, I got to thinking that having a metal boat probably would not matter.

If the trim works after you replace the fuse, with the shifter in neutral and the motor off....but it blows if you push the shifter into forward and blow the fuse when you trim in forward, the most likely place to look is to follow the wires from the trim switch where they go through any move part of the shifter. One of the three leads may have had the insulation rubbed off and the bare wire is touching the shifter metallic parts. If you boat is metal, the shifter is grounded through the boat, if it is not metal the shifter is grounded through the control cables to the engine.

Those wires move as you shift. So in neutral, it may or may not short to ground.

Mike
 
Thanks Mike!!

The hull is Kevlar/Carbon Fiber.

I'm not sure if it blows asap after starting or not, as I only know it's blown after starting and when I'm get on plane an go to trim up the motor the power trim & tilt on the binnacle doesn't work and so far that means everytime I turn off it's blown. Although the PT&T switch on the side of the motor works perfectly.

The Honda Dealer said they checked all possible connections and started it multiple times across multiple days with no issue...however that's no different from when I picked it up after they put in a new wiring harness where it ran perfectly all day (starting & stopping & using PTT) on a Sat and then on Sunday blew a fuse one initial run of the morning. So hopefully whatever connections they checked or cleaned fixes the issue.

I'm going to disconnect the tach for sure.

I hope to pick the boat up later this week and will not be able to water test until next week and will report back what I find. So Stay Tuned.

THANKS!!!
 
If the trim works after you replace the fuse, with the shifter in neutral and the motor off....but it blows if you push the shifter into forward and blow the fuse when you trim in forward, the most likely place to look is to follow the wires from the trim switch where they go through any move part of the shifter.
Click to expand...

Interesting!! This sounds more like what is happening and I'll be sure to ask the mechanic and/or check myself after I pick it up. Stay tuned.

The best I can recall is that it is NOT happening when the shifter is in Neutral and instead is happening when I put in gear, hit the throttle and then go to trim it up.
 
I may be going down the wrong path by focusing on the shifter/trim switch leads....but....

The trim switch on the engine is powered differently than the one on the dash. The wire that feeds the key switch with power, also provides the power to the shifter's trim switch.

The key switch has a ground in it, and it can short internally....but I think you mentioned that they changed that.

The trim switch leads in the shifter, go down the arm, then they wrap around the pivot at the bottom of the shift arm a couple of times, then are routed out through the base of the shifter. It is not unusual for the insulation of these wires to wear, especially if someone hadd remove the shift handle and the routing was not reinstalled properly.

The way to physically check, would be to remove the shifter arm and closely inspect the three wires. If you take it off, take pictures of how the wire is wrapped around the shift arm, so you can put it back correctly.

If you can accelerate and not use the trim and can stop the engine and restart it....but...if the fuse blows only when you trim, then the short is from either the blue wire or the green wire to the trim switch.

Let us know how things come out.

Mike
 
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