SHOCKING THE #$%@ outta me!

gaviotapete · 19 August 2006, 17:45

So there we were having pulled up to a sweet surfspot after a fairly smooth 20 minute passage. We set the hook and then i went to turn off the motor
at the keyswitch and ZZZZZZZST. While we deliberated over what to do we found that many things we touched were shocking us too; even the nylon kill switch was sending current! Not wanting to be stuck there we decided to pull anchor, which was also now shocking me, and head for port. She ran like a champ all the way home doing 20knts and as we were close to the beach we were to land on I yanked the kill cord to shut her down. That did'nt work so we pulled the gas line and waited for it to run down.

We got her home and while washing her down decided to try to start the engine to flush it out. No problem now and she started and turned off as normal. Anybody else have experience with this type of problem? We did not have too much water/more than the usual, on board. The throttle control (Mercury/Quicksilver, 1989) was not shocking me but the kill cord was. When I first noticed the shocking at touching the key I yelped a little and then touched it again (smart guy) and then turned it quickly to the off position. This did not turn it off but now it seemed to electrify the kill cord which I then took off my wrist. This is the point where we decided to run home while we still had the motor running. As mentioned earlier I pulled the kill cord once we got close to home (as the key was still in the off position and not having the desired effect) and that did not kill it.

Under the cowling we did not see anything obviously loose or abraded.
So my question is this; how do I track the short circuit? Where is the likely place to start? Any and all suggestions gratefully welcome. The motor is a 1989 model Mercury 40hp 2 stroke injected. Thanks,

gPete

jwalker · 19 August 2006, 19:12

Pete, do a search cos I remember there being a thread where someone else had a similar problem. I was a while ago.

Biggles · 19 August 2006, 19:34

I had a shocking experience when I was fiidling with some elctrics at sea. Turned out to be a dodgy kill switch connection.

The presence of water and high voltages made for a very nasty feeling.

I suppose if you've got a wet/damp boat high voltages could go anywhere and give you all sorts of funny shocks.

Not too sure of what your problem exactly is but I suugest you make sure you have a fire extinguisher on your boat.

Nos4r2 · 19 August 2006, 20:25

What sort of shock was it? HT lead type kick or 12v tingling?

Richard B · 19 August 2006, 20:29

Quote:

Originally Posted by jwalker

Pete, do a search cos I remember there being a thread where someone else had a similar problem. I was a while ago.

You're right - He was called Pete too! I suggested he run the engine with the cover off on the dark, and hey presto - there was the problem! He could see a blue haze around the plugs and HT leads at the current tracked down to earth. A good cleanup with solvent was all that was needed and once dry all was OK.

gaviotapete · 19 August 2006, 21:09

thanks for the replies. I'm not sure what HT leads stands for, but the shocks were much more than 12v tingling and much less than house current type shocks, in other words, enough to make you jump but not enough to make you yelp. i'll try to find the other thread and see if i can figure it out.

Richard, if i try to run it in the dark and see a blue current will that lead me to my short? as you may have guessed i am not well versed in electrical
matters.

gpete

Nos4r2 · 19 August 2006, 21:18

that sounds like HT shock from the plug leads-though 12v on wet hands produces more of a kick than you'd expect.

gaviotapete · 19 August 2006, 21:28

what's HT? hot terminal? and what can i do about it? is there an obvious way to try and isolate the problem? i'm at a loss as to how to start (other than try running the motor in the dark and looking for sparks??)

BogMonster · 19 August 2006, 21:29

HT = high tension = high voltage i.e. the spark plug leads

jwalker · 19 August 2006, 21:31

HT = high tension = plug leads

jwalker · 19 August 2006, 21:31

Snap!

gaviotapete · 19 August 2006, 21:39

Quote:

Originally Posted by Richard B

You're right - He was called Pete too! I suggested he run the engine with the cover off on the dark, and hey presto - there was the problem! He could see a blue haze around the plugs and HT leads at the current tracked down to earth. A good cleanup with solvent was all that was needed and once dry all was OK.

Do i clean the wires that connect to the spark plugs with solvent? If the kill switch was not working while we were out on the water and then working once we got her home does that tell me anything? sorry to be so ignorant about what sounds like a not to difficult problem and thanks again for the replies.

Nos4r2 · 19 August 2006, 21:45

I'd do that anyway just to eliminate it.

Holts Damp Start is quite useful for keeping the water out after cleaning them-it's a spray on waterproof plastic film. Don't use it on anything other than electrics and once it's on you need to spray it again if you disturb anything (changing plugs etc)

gaviotapete · 19 August 2006, 21:57

Quote:

Originally Posted by Nos4r2

I'd do that anyway just to eliminate it.

Holts Damp Start is quite useful for keeping the water out after cleaning them-it's a spray on waterproof plastic film. Don't use it on anything other than electrics and once it's on you need to spray it again if you disturb anything (changing plugs etc)

thanks nos. let me see if i understand what you guys are saying:
its possible that the HT leads are dirty and cleaning them with solvent and then spraying them w/Holts will seal out any moisture that is getting in thereby solving the shocking problem. does this sound correct?

Nos4r2 · 19 August 2006, 22:25

yep. It's cheaper than replacing the leads if that ISN'T what the fault is too.

gaviotapete · 19 August 2006, 22:29

thanks for your help

gpete

gaviotapete · 20 August 2006, 00:46

Quote:

Originally Posted by jwalker

Pete, do a search cos I remember there being a thread where someone else had a similar problem. I was a while ago.

JW, any tips on finding that thread? i checked posts by petes and shock and short circuit but still no joy.

jwalker · 20 August 2006, 09:26

http://www.rib.net/forum/showthread....electric+shock

Richard may guide us to the one he had in mind.

Richard B · 20 August 2006, 11:35

It'll be too long ago to search I think! The search facility only seems to go back about 2 years. If I remember correctly, Pete's spark plugs were tracking down the ceramic so he just gave them a good clean and the job was done.

Biggles · 20 August 2006, 18:01

I had cracked spark plugs on a car once. It also affected the running of the engine.