Multi System Failure???**More New Information**

Ok I already typed this once gonna try again..... Was out on the water today running about 35mph started hearing a rapid sputter / spitting puffing??? sound None of the guages were affected good temp, oil pressure ect....slowed down and went to a safe area to check it out...went back to open the box actually couldnt hear it as well opened the box I noticed about 3 tbsp of oil in the bilge and some faint light smoke comming from the base of the valve cover?? somewhere around the carb... So I thought maybe a gasket failing. Figured Id watch the guages and limp back as I was still a long way out I got about two miles down and the boat shut down dead in the water. As first I thought it seized but I could jump it at the solenoid and it would turn over fine but wouldnt start....checked all the wiring around the motor and everything looked ok...I went back to the front and turned the key to on (not start) and the motor tried to turn over??? Looked under the dash and the wires going to the ignition switch were very hot and the casing on the purple wire was melting.... Figured at that point i was lost and figured wasnt anything I was going to fix on the water even if I did know what it was so I disconnected the battery and called a tow. A side note I noticed the RPM gauge was stuck like the boat was still running and this morning I had to tap the volt meter to get it to read?? Thanks in adance!

Re: Multi System Failure???

Re: Multi System Failure???

what make/model of engine do you have??

points/electronic ignition??

Re: Multi System Failure???

Re: Multi System Failure???

Sorry about that.....Its a 1994 Mercruiser 3.0 Pretty certain electronic ignition (thats a bit embarassing that I dont know for sure :redface

Re: Multi System Failure???

Re: Multi System Failure???

sounds as though the key switch may be at fault here

possibly shorting out and causing the starter to engage while in the "run" position - the noise you heard may have been the starter engaging with the flywheel

cheap/easy to replace a key switch, just get the wires right - S=yel/red, I=pur, B=red

Re: Multi System Failure???

Re: Multi System Failure???

Thanks Dubs, thats where I will start after I make sure I dont have any melted bare wires I'll get a new switch

Re: Multi System Failure???

Re: Multi System Failure???

As luck would have it no one close by has a key switch, is there a safe way to bypass the swith just for testing until I can get a new switch?? Also is my RPM gauge fried because it is still reading like the boat is still running or will I not know until I get it started?? Thanks again!

Re: Multi System Failure???

Re: Multi System Failure???

Your tach may be the issue. Disconnect it and see if the issue clears.

Re: Multi System Failure???

Re: Multi System Failure???

Good idea I disconnected the purple wires and turned the switch to on no hot wires...still won't start..... I connected the purple wires together wires got hot again ?????? Sorry if I seem ignorant I know old Honda wiring not boats lol

Re: Multi System Failure???

Re: Multi System Failure???

Ok..... Went a little crazy disconnected all of the gauges still same problem.... Hooked a volt meter up and attached it to the purple wire at it's last connection before the large bundle going towRds the back of the boat and the 12v hot wire the meter read 12v so I have another short somewhere???

Re: Multi System Failure???

Re: Multi System Failure???

best way to determine if you have a boat wiring issue or an engine wiring issue is to diconnect the 10-pin harness connector at the engine

troubleshoot both sides and see where the problem lies - then you can focus on boat wiring or engine wiring

definitly helps to have engine wiring diagrams, a good digital multimeter, and a firm knowledge of how to use it

Re: Multi System Failure???

Re: Multi System Failure???

dissconnect feed for tach at one of the posts off coil.then see if you have 12v at coil with ignition switched on.if not could be microswitch in throttle controller or shift switch being faulty.pop dizzy cap and tell us if it has points?

Re: Multi System Failure???

Re: Multi System Failure???

Well dubs I wish I did have a diagram I do have the meter and a medium firm grasp on how to use it I did disconnect the 10 pin and noticed one of the pins had definately gotten quite hot inside the connector, the purple wire on the boat side looked like it had gotten soft and motor side looked ok, didnt go much farther cause it got dark on me or maybe i was called to supper...anyways...... Also did pop the cap no points just a GM module, and a little oil?? Cap and rotor were good and clean. I have trcked down and fixed all kinds of gremlins on the old wing but this is a different world and has me stumped

Re: Multi System Failure???

Re: Multi System Failure???

a wiring diagram is ket for troubleshooting, it gives a breakdown of the ten pin harness - the number pin for the corresponding wire

the two big pins i know are main (red) battery power and ground (black)

the others are for solenoid (yel/red), ignition (purple) and the various sender wires

if you knew for a fact which pins were for which wire, it would be quite easy to "jump" the engine and run it with the harness disconnected - this would help greatly in troubleshooting

there used to be links to mercruiser service manuals here but i think they are all invalid now, you may be able to ask freinds or beg a local shop to give you info on wiring diagrams

it sure sounds to me like the key switch is the culprit, too bad you couldn't replace it

you can try by disconnecting the wires from the key switch, connecting the red and purple wires with a jumper - this will energize the ignition circuit, then apply 12 volts to the yel/red wire - this will turn the engine over

if the engine runs and all guages are working, then the switch is faulty

Re: Multi System Failure???

Re: Multi System Failure???

The wire inside the connector got hot enough I couldnt read which number it was that and it was getting dark and I was getting frustrated. When I touched the red and purple together they got very hot pretty certain Ive got a short somewhere else....I am going to get a new switch it still may have started there. I may just run a new wire from the gauges all the way to the connector maybe even bypass the connector, need to do some research to see if there are any splices, that way I know at least all that is good. Just throwing this out there could a bad coil caused all this??

Re: Multi System Failure???**New Information**

Re: Multi System Failure???**New Information**

Was getting in my truck to make the trip to the closest parts store to purchase a switch and thought I would give it one more closer look...I tested the switch with my meter seemed fine, so I started tracing that D&%$N purple wire again, after unraveling several nasty feet of old tape I finally found it....about a two inch melted area, where the purple bundles in with the neutral switch, choke and temp sending unit. It ran under the water hose and the area was on the very end near the exhaust so I couldnt see it until I disconnected all the wiring and pulled it back around over the hose. I also found where the previous owner changed to a single wire alternator and the lead wires that were disconnected were soaked in oil (inside the tape). So.... a couple questions and I think I'll be back in buisness. Do you think I can safely assume (I hate that word) that the short was caused by the heat from the motor and just rewire that area and be done? Or should I keep looking for a potential secondary cause. Also while I rewiring should I go ahead and bypass the 10 pin connector where it got so hot?? After all that I can go back to looking for the original "funny noise" I was hearing.... Thanks again for helping me think my way through this!!

Re: Multi System Failure???**More New Information**

I believe I sorted out my wiring woes.. Had a little trouble with the connector at first not making good connection. I was able to start the boat it ran for a minute, voltage meter wasn't registering RPM gauge was... The boat only ran about two minutes then shut down was able to restart once but same thong happened. I'm thinking maybe something may have been damaged but I'm at a loss as to what.... Do I need to go back to the switch being faulty??? Any suggestions will be most appreciated!

Re: Multi System Failure???**More New Information**

they have manuals they are up in the stickies jsut download the one for your engine.

that switch where the shift cable is isnt a neutral saftey switch its a shift interrupt switch it stalls the engine jsut for a split second when shifting out of gear back into neutral so the clutch dog in the lower unit will disengage the gear easier.

i would check for constant 12 vlots with the key on at the purple wire at the coil and other places it goes ie gauges key switch etc. and check out the wiring where you found that mess. check your grounds to.

Re: Multi System Failure???**More New Information**

Thanks 127... I was actually reffering to the key (ignition) switch that was suggested earlier in the thread..... I plan on going back through everything again just to make double or maybe it's triple by now lol!!