73 mercury 1500 inline 6 help with ignition

[bbennet2]

I'm a newbie here guys. Just bought my first boat last summer venture 1800 bass boat with a non running 73 mec 1500 power tower on it. Gave next to nothing for it. Redone the boat now I'm working on the motor. Motor looks super clean, I had to replace the internal harness due to the old was chewed up. I tried turning it over by jumping the starter, motor turned but super slow sounded like battery was dead but I had a full charge on it. Removed plugs and it spun fine. Any thoughts? Next question is the plugs, they were gapless anyone know the right plugs to use on this thing? 3. Last question if I replace the switch box with new CDI switch does it also replace the ignition coil? The instructions state not to hook it to the old ignition coil cause it will burn up the new switch box. Thanks guys want to learn any help appreciated

 

[WA-Newb]

Re: 73 mercury 1500 inline 6 help with ignition

I spent a couple hours searching yesterday to see if there were better plugs for this motor (same as mine) and I came up with the best ones are what is called for in the spec sheets...they are the gapless ones like you said (there is another term for these just forgot what it is).
This is the plug numbers:
NKG-BUHW
or people do run Champion QL76V (some say just L76V are fine and cheaper).

My motor is also spinning sluggish as you know (saw your post in my thread) and I will let you know what I find out..if anything...sigh...lol
I have taken the main wire harness out now and found the reason I had to jump the solenoid...the "chewed" up or disintegrated wire housing went down into the main battery cables maybe in a bend or something but its all junk about two feet from the wire harness plug.

I was also told to take the cap off the distributor to see if it spins freely....will be trying that today hopefully.

I can't help with the CDI questions...over my head as I am new to all of this.

Good luck.

 

[bbennet2]

Re: 73 mercury 1500 inline 6 help with ignition

I appreciate the response. Decided last night to start a complete tear down. I started this morning and so far all is well. Rings look great. I'm going to go forward and remove the carbs as a unit and start a cleaning and rebuilding project on them.

 

[Laddies]

Re: 73 mercury 1500 inline 6 help with ignition

If either of you continue trying to start those engine with the bad starters or what ever is causing the engines ot not turn freely you will be replacing the switch box and more as anything below 9 1/2 volts will fry the box. Till you find out whats causing the draging problem with the starter disconnect the white wire from the switchbox 4 terminal side so the low voltage don't harm the ign system.

 

[WA-Newb]

Re: 73 mercury 1500 inline 6 help with ignition

Thank you Laddies...That's good to know since any component like that will probably cost what i paid for the whole setup...lol

I didn't get a chance to work on mine at all yesterday (doubt I will again today) but was wondering if you possibly knew what would cause my motor to die when I unhook the battery while it's running? I have to jump from the battery positive to the starter solenoid with jumpers because of a bad positive cable but when I unhooked that while motor was running it instantly died.
Since I have found so many bad wires I am wondering if there is one that I am not seeing that goes from ignition key..but doesn't make sense to me that it would be tied through the solenoid at all.
Thanks.

Bennet..you have more guts than I do, that's for sure...lol
Hope is goes well for you.