'77 Merc Tower of Power won't start - Video Link Included

bsutravis

Seaman
Joined
Jun 11, 2010
Messages
64
Wow! Thanks jimmbo! Lots of testing I can perform to try and narrow this down! I'm off for the next few days so I'll be working on it! Thank you!
 

bsutravis

Seaman
Joined
Jun 11, 2010
Messages
64
Plot thickens.... Since I once had spark on my old harness, and now I don't with the used harness I just installed I figured my spark issue has to be somewhere in that harness. I checked for continuity in from the big harness plug that goes into the motor and discovered that the pos and neg were reversed! I switched the terminals at the battery and I got 12+ volts at the red terminal on my switchbox. I then went to try and start it up and now the starter spins, but the bendix isn't moving up and engaging the flywheel. It appears that now the starter is rotating backwards, thus the bendix staying down. Reverse polarity? I have replaced the starter and the starter solenoid, could the wiring be reversed somehow at the solenoid? Any other ideas for a starter turning the wrong way?
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,003
Your starter should have a permanent magnet for the field. If the magnet is inverted, the starter will spin backwards. If you replaced the starter, I would guess it is assembled correctly.

The negative battery cable should connect directly to the lower cowling, near the fuel pump. The positive battery cable should connect to the starter solenoid large post. Your starter should have a ground cable from the upper cowling support to the top frame of the starter. The bottom post of the starter is for +12VDC. Is that how it is wired?
 

bsutravis

Seaman
Joined
Jun 11, 2010
Messages
64
Update: I got all the wiring figured out and low and behold there was a white wire that was not wired correctly at the new ignition key switch. Once connected it gave me 12v to the white and red terminals on my switchbox. I turned it over and it wants to start but my battery is weak from all the cranking I've done so I just slapped the charger on it and once it's charged I'll give it another attempt at starting up.
 

bsutravis

Seaman
Joined
Jun 11, 2010
Messages
64
I just tried to start it on a full charge (13+v) and it did the same as I originally posted as my issue. I'm getting good spark, but it turns over and the moment it starts to fire the starter disengages since it thinks the motor is about to run, but then it dies. I've sprayed a fuel mix into the carbs as well as plug holes and still the same result. I'm left scratching my head! I'm getting spark, but it doesn't want to run even with fuel sprayed into the carbs.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,003
Are you choking the daylights out of it? Is the cold start lever all the way up? Spray some fuel into the carbs, Engage the choke and hold it and crank until she fires and runs.
 

bsutravis

Seaman
Joined
Jun 11, 2010
Messages
64
Yeah Chris, I'm choking with the lever all the way forward... I've sprayed fuel mix and even starting fluid (I know it's bad) into the carbs and it coughs like it wants to go but it just won't. I've noticed also that the motor really jumps as it's trying to start, more than it use to... I don't know what that's telling me. Is there any way this thing could have jumped time or something like that? I do have a timing light I can get but I'm unsure how to check the timing especially if it's not running.
 

Chris1956

Supreme Mariner
Joined
Mar 25, 2004
Messages
27,003
Timing is easy to check. Remove spark plugs 2-6, install them into their wires and ground their bases to the block. Put timing light onto #1 spark plug wire. Remove prop.

Put motor in gear and advance throttle until carbs are ready to open, but still closed. Jumper starter solenoid and check timing. The timing should be between 4*-6* BTDC. This is idle pickup timing.

Now advance throttle fully and check timing again.. Max spark advance should be 21*BTDC.
 

bsutravis

Seaman
Joined
Jun 11, 2010
Messages
64
So frustrated..... After following all advice on here I still couldn't get the motor to run, so after much searching I found a mechanic that works on older motors. He's located at a boat salvage place in Indianapolis and all he does is fix old outboards for resale and for customers. Long story short, he calls me this morning and acts like there's no way my motor was ever running. Starts rattling off all sorts of things he's found wrong and said there's no way it was running. Said all the carb idle screws were about to fall out, missing carb hoses (which it's never had), melting in distributor, bad stator, bad rectifier........ I don't know what to do now! He didn't recommend fixing it because he admitted that he's not sure 100% what is wrong with it! Grrrrr.
 
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