1973 mercury 115 horse NO SPARK

[jeff9501]

Hi I have just purchased a 1973 glastron boat with a 1973 115 mercury outboard engine . The person who I bought it from has owned it for a number of years . He said he started it this spring and it ran great I just bought it a week ago . He started it when I was there and I heard it run sounded ok . I had it in the water a few days later at first it didnt want to start I saw some fuel dripping out the engine cover I put the engine all the way in the water and it started it worked great that day ! I had it out the other day I squeezed the primer ball a bit tried to start the engine cranks over good but no start . I saw fuel again dripping out of the cover I thought it was just flooded and if it sat for a bit it would probably start right up. No such luck after a about an hour and still no start I towed it home depressed ! The next morning I tried again with a garden hose attached at home .. still nothing after a bit of investigation it seems that I hAve NO SPARK . So this is the point I am at the repair shops are all 4 weeks behind so I need to take care of this somehow my self .. this is an older engine with a disributor cap so any Ideas or suggestions that might get me out fishing would be greatly appreciated ......................Jeff

 

[njrextreme]

Re: 1973 mercury 115 horse NO SPARK

How have you verified it has no spark? These motors are cold starting sons a b's. You need that primer ball rock hard. You also need a fresh charged batt.. The way I start mine is in N about eighth throtle and hold the choke in and crank it over. You prob. have the merccontrol so you will need to pull the lever on the control up while in the N position. As far as your gas leaking out, it is from bad needle and seat in the carb/carbs. They sell rebuild kits for them. Pull a plug and wire, have someone crank it over and see if it arcs off a bolt on the block. If you still have no spark I can point you in another direction.
NJREXTREME

 

[jeff9501]

Re: 1973 mercury 115 horse NO SPARK

hi thanks for the reply yes I have no spark I have confirmed this

 

[Chris1956]

Re: 1973 mercury 115 horse NO SPARK

Jeff, Those old wiring harnesses fail whenever. Test for +12VDC on the white wire on the starboard side of the switchbox. It should be hot all the time. Now test th red wire next to it. It whould be hot, when the ign key is in the run position.

Post back your results.

 

[jeff9501]

Re: 1973 mercury 115 horse NO SPARK

thanks everyone but no solution yet . I found that there was no continuity between the coil wire and the dist cap electrode . I found some spare electrodes in the boat (thank god) I have since replaced the electrode and now have continuity. The white wire on the starboard side of the switch box has 12 volts when the key is on run only and the red wire also has `12 volts ??????? .................thanks for the help all I have a good feeling that I will resolve this soon (IHOPE) ..any more suggestions would be great I have since found a color coded ignition schematic ...........I want to be fishin

 

[emckelvy]

Re: 1973 mercury 115 horse NO SPARK

Here's the entire test for this ign, with a working switchbox and coil you can definitely confirm a bad distributor trigger housing assy. If you can get no spark out of the switchbox when bypassing the trigger, most likely it's the switchbox. Very Very rarely do coils go bad and you can generally do a resistance check to rule out a coil. HTH..............ed

"MERCURY BATTERY-POWERED CDI TEST FOR DISTRIBUTOR MODELS

This test is for the 332-2986 switchbox used from 1967-1978 on all the inlines.

This test assumes your coil is good (problems with CDI coils are rare).

DISCONNECT BATTERY

1. Turn off ignition;

2. Disconnect all 3 distributor wires on the Port side of the switchbox (and the ?mercury switch? if present);

3. Remove the HV lead from the ign coil to the center of the dist. cap (remember it unplugs from the coil and unscrews from the cap);

4. Reconnect the HV lead to the COIL only;

5. Position the free end of the HV lead approx. 3/8" from ground (block, shrouds etc), and find a way to hold it there;

6. Jumper the brown and white terminals on the dist. side of the switchbox to each other.

RECONNECT BATTERY

7. Check that you have +12V at the red terminal (even with the ign off);

8. Turn on ignition and verify +12V at the white terminal (same side as the red terminal);

9. Ground the black terminal on the distributor side of the switchbox - this should cause a spark each time you touch ground.

If you get spark with the distributor bypassed, and it won't fire with the distributor connected, the trigger is bad and the entire distributor housing assy must be replaced.

If you get no spark using the test, the switchbox is probably bad. In that case, be sure to check for correct power on the switchbox, check all connections, and check the coil's resistance to make sure it's OK."

 

[Clarky_kris]

Re: 1973 mercury 115 horse NO SPARK

How do u check coil resistance?? Can I do it with a regular volt meter?

 

[donzi gt230]

Re: 1973 mercury 115 horse NO SPARK

most volt meters will measure resistance--ohms setting. You have to know how to use your meter and know the resistance spec for the part you're testing. I'm not the knowledgeable one with the test specs, but it looks like coil resistance would be last on the list so follow the instructions given and you'll probably find the problem before you get there.

BTW, if your coil wire was truly bad, it's hard to imagine two things failed in the ignition system at the same time. ??

 

[Clarky_kris]

Re: 1973 mercury 115 horse NO SPARK

Just incase u missed I am another person with a simular problem... So I thought this may be a good spot to ask how coill resistance was checked...
I did the "MERCURY BATTERY-POWERED CDI TEST FOR DISTRIBUTOR MODELS" and got no sparks from grounding black wire.. This means mmy trigger is good... So must be problem with switchbox or coil.. My engine still sputters and runs at idle then will loose spark when throttle Is increased..
Anyone have any input on fixing?


Thanks, Kris

 

[Chris1956]

Re: 1973 mercury 115 horse NO SPARK

Kris, I have never seen a Merc coil breakdown at higher RPM. I have seen the plug wires arc, at higher RPM. You might check them.

Check voltage at the switchbox on the red and white wires on starboard side of switchbox. They should be near +12VDC at all times. Look for bad wiring on the motor harness.

Finally, those old boat harnesses get brittle with age and wires break all the time.

 

[jeff9501]

Re: 1973 mercury 115 horse NO SPARK

Update : I did the test for spark and yes I could make the coil fire by grounding the black terminal .... after I cleaned all terminals on switch box ...still no spark sooo I guess I need a trigger switch now is there anything that goes wrong in the distributor that is fixable ?? or just replace as parts are very hard to find here .................thanks Jeff

 

[jeff9501]

Re: 1973 mercury 115 horse NO SPARK

Is there a way to bench test the distributor ? I have been pricing out trigger assemblies and I would like to be sure that this is the problem before I buy one online ....can you use an ohm meter to check ???

 

[emckelvy]

Re: 1973 mercury 115 horse NO SPARK

If you are getting sparking when you bypass the distributor as per the CDI test, and no sparks with the dist. hooked up, the dist is bad.

This is another 'no spark' thread, check out the postings for more info on replacement:

http://forums.iboats.com/showthread.php?p=2817546&posted=1#post2817546

Note that your distributor should mount with thru-bolts and if so you can access the nuts underneath & won't have to pull the flywheel.

HTH..........ed

 

[Clarky_kris]

Re: 1973 mercury 115 horse NO SPARK

On my spark test I do not get spark when grounding black wire... I have 12v on white and red wires on switchbox.. My engine runs... Bearly at idle spitting and sputtering.. But still missing.. When given throttle it dies.. Cleaned all connections on switchbox and tried new plugs.. Same problem.. Also when ignition was turned to on position I could hear clicking from or near the switchbox.. Any help???

 

[jeff9501]

Re: 1973 mercury 115 horse NO SPARK

Update: I found a supplier within 6 hours of home who has a trigger switch. It is coming over night , I have found that I am not lucky enough to do this without removing the flywheel ..... so I see the flywheel has a master spline now how do I ensure that my distributor is installed in the right position is there a timing sequence .... find tdc number one cylinder ??? any more help greatly appriciated

 

[Chris1956]

Re: 1973 mercury 115 horse NO SPARK

Jeff, You need a service manual, especially to install the trigger assembly.

Initial Timing is easy. Set the motor to TDC on #1 cylinder. Remove the cover on the distributor pulley. Set the cast in arrow to point at the punch mark on the flywheel, and install the timing belt.

See if you can find the "Timing and Synchronizing of Inlines" topic on this forum or it may be a FAQ. That will walk you thru the idle pickup and max timing events.

 

[jeff9501]

Re: 1973 mercury 115 horse NO SPARK

Thanks everyone I am again up and running. The whole operation was relativly easy !