75 Merc dead in the water..what happened?

danthern

Petty Officer 1st Class
Joined
May 28, 2003
Messages
217
Hey Guys...just bought a 81 15 ft Titan Thundercraft with a 75 mercury. Third time out today, was running great, pulling the kids on a tube. As I was idling while the youngsters were climbing back on the tube, she dies and a buzzer goes off. Overheating?? Recently replaced impeller per the last owner. The water was circulating earlier as evidenced by the peehole stream. I've been an I/O man, first outboard. She wouldn't restart, had to be towed. Incidentally, the part of the wiring harness that comes from the ignition switch was very hot. Aleso the motor wouldn't turn over unless I advanced the throttle.... nuetral safety switch issues?? I'm baffled. Any help appreciated.
 

danthern

Petty Officer 1st Class
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May 28, 2003
Messages
217
Re: 75 Merc dead in the water..what happened?

Update....after allowing the boat to sit for a couple hours, I put the muffs on and attempted to restart. No luck, and I noticed smoke coming from beneath the console near the ignition switch. The switch itself was hot as Hades...what the heck's going on?<br />Thanks
 

emckelvy

Commander
Joined
Jan 16, 2004
Messages
2,506
Re: 75 Merc dead in the water..what happened?

Sounds like you had some kind of short or other electrical failure in the ign switch or attaching wiring. Could even be the reason for the horn going off.<br /><br />Certainly bears further inspection, you'll have to get at the switch and wiring to check it out. Might be a good idea to disconnect the battery first!<br /><br />HTH & Good Luck.........ed
 

ronmold

Petty Officer 1st Class
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Sep 8, 2003
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240
Re: 75 Merc dead in the water..what happened?

What year is motor?
 

danthern

Petty Officer 1st Class
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May 28, 2003
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217
Re: 75 Merc dead in the water..what happened?

Sorry...the motor and boat are 1981
 

Trent

Captain
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Nov 17, 2001
Messages
3,333
Re: 75 Merc dead in the water..what happened?

With a Merc this old you probably have some rotten wires which is common. Check the powerhead wires for missing insulation. My bet is you got a wire touching ground. <br /><br />What city in Alabama?
 

danthern

Petty Officer 1st Class
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May 28, 2003
Messages
217
Re: 75 Merc dead in the water..what happened?

I got to poking around under the console and sure enough Trent, found a bare wire from the harness to the ignition switch (a blue one). Looks to be pretty easily replaceable. Would that cause the boat not to start as well as causing the alarm to sound? Checked fuel system to the carb, it's OK...By the way Trent, I'm in Opelika, Al. Next door to Auburn (War Eagle!)...Keep the advice coming! Many thanks
 

danthern

Petty Officer 1st Class
Joined
May 28, 2003
Messages
217
Re: 75 Merc dead in the water..what happened?

upon investigation, looks like my blue ignition wire is burned from front to back. should I replace the whole harness or can I just replace the one wire? I ran a wire from the terminal on the powerhead directly to the switch and it immediately got hotter than fire. My elecrical skills kinda suck....any words of wisdom?<br />Thanks
 

ronmold

Petty Officer 1st Class
Joined
Sep 8, 2003
Messages
240
Re: 75 Merc dead in the water..what happened?

If that wire is in the harness it probably burned thru other wires also. Time for a new wire harness. I would remove and check the Ign. switch for proper operation. If any parts go bad in the ign. sw, which can happen when they get old, shorts can occur because the switch has both ground and +12v running to it.
 

danthern

Petty Officer 1st Class
Joined
May 28, 2003
Messages
217
Re: 75 Merc dead in the water..what happened?

Problem solved! Burned wires were indeed the culprit. Checked the harness and didn't see any other wire damage, but will scout around for a new one anyway. Many thanks to all who helped. What a great resource this site is!
 

Elmer Fudge

Lieutenant Commander
Joined
Aug 25, 2003
Messages
1,881
Re: 75 Merc dead in the water..what happened?

What caused the wires to burn out?
 

danthern

Petty Officer 1st Class
Joined
May 28, 2003
Messages
217
Re: 75 Merc dead in the water..what happened?

had one lying on the powerhead...guess it got hot, burned off the insulation and shorted.
 

Trent

Captain
Joined
Nov 17, 2001
Messages
3,333
Re: 75 Merc dead in the water..what happened?

Glad you got her fixed!<br />From Troy...
 

H2OFLY13

Recruit
Joined
Jan 27, 2011
Messages
2
Re: 75 Merc dead in the water..what happened?

I have a Titan Thundercraft 1980. It has been in the family since it was new, I would love to see a pic of your boat!
 

Moody Blue

Captain
Joined
May 24, 2004
Messages
3,136
Re: 75 Merc dead in the water..what happened?

H2O, this is a 7 year old thread, and the original poster has not posted here since 2006. Not likely you will get any photo's from him:)
 
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