Mercury Ignition?

[dstuard]

Just had to replace the switch boxes on 83 Mercury 115 HP. Now it is really sluggish out of the whole. When it does get on plane it will miss at full throttle. If I back off just a little it runs fine. I misted the carbs and it made it bog down even worse. Changed the plugs and still no better. I have spark to all when it is idling and it could not idle any better. Any ideas? How can I check the coils when it only does it under a load? Could this still be a fuel problem even though the mist did not help? I am stumped and I would like to use my boat at full speed for once.

 

[Gold Bear]

Re: Mercury Ignition?

dstuard <br /><br />How are the idle mixture screws set, ie. how many turns are they open from lightly seated are they?<br /><br />Gold Bear

 

[dstuard]

Re: Mercury Ignition?

They are around 1 and a half to two from being seated. I tightened them down until it started sputtering and then came out about a quarter turn. I did an ohm check as per the manual. Trigger and coils were all in specs. Stator was slightly outside specs. Red to blue was 6900 and red/white and blue white was 6750. The spec says 4500-6200. Red/white to ground was 123 and is supposed to be 125. Are these far enough out of spec to cause my problem? I made a dva meter but have a hard time getting a reading. My stator might be bad if I made it right. With it idling I still am not much over 100 DC volts on the reds to ground. Should I be on Ac? I will conquer this beast with the help of this board. I also read a post about blue coils and champion plugs. I have l76v.

 

[dstuard]

Re: Mercury Ignition?

Bump

 

[dstuard]

Re: Mercury Ignition?

^^^

 

[Gold Bear]

Re: Mercury Ignition?

dstuard <br /><br />"They are around 1 and a half to two from being seated."<br /><br />That is not enough. Set them at 2-1/2 turns. Test operate. If it still bogs open all three 1/4 turn at a time until the bog goes away.<br /><br />My 115 operates best at 3 turns open.<br /><br />Good Luck,<br /><br />Gold Bear

 

[dstuard]

Re: Mercury Ignition?

I did try messing with that last time we were out. I guess I will just pull the carbs and clean them. Can't hurt anything and I know that I ran some bad gass in it at the beginning of the year. How would I check the reeds on this one when I get the carbs off?

 

[jim dozier]

Re: Mercury Ignition?

Also, after you redo the carbs again, I believe the proper way to set the idle mixture is after the initial opening specified in the book adjust it for the best idle, THEN back it out (richen) it 1/4 turn. If you turned it in till it sputters and then backed it out 1/4 turn, you are too lean at idle and even if it idles adequately it will be too lean for acceleration and mid range away from idle. <br /><br />You should be able to visualize the reeds with the carbs off. If they're not busted I would leave them alone.

 

[dstuard]

Re: Mercury Ignition?

Took off the carbs. Does not seem to be any varnish but there was lots of debris. I don't know if this is the problem but it definitely will not hurt. I could see the stator wires a little easier and the yellows are bare in a couple of spots. Looks like they are too close to the stator to repair. I think I will just replace the stator while I am at it rather than fry another switch box. Looks like I have my work cut out for me. Will I have a hard time getting everything back in sync after I get it all back on?

 

[rickdb1boat]

Re: Mercury Ignition?

Put a little liquid electrical tape on them, if the stator is still good.

 

[dstuard]

Re: Mercury Ignition?

I am not sure if it is still good or not. It runs but misses at full throttle. I guess when I get my carbs back on I can give it a try and see if it fixed it. Any chance the bare wires (yellow only) would cause the high speed miss?

 

[jim dozier]

Re: Mercury Ignition?

I don't know if the bare wires are causing a miss electrically, but it sounds like the insulation on them that is disintegrating is getting into your carbs and that ain't good and might cause a miss all by itself.

 

[Gold Bear]

Re: Mercury Ignition?

dstuard <br /><br />"When it does get on plane it will miss at full throttle. If I back off just a little it runs fine. I misted the carbs and it made it bog down even worse."<br /><br />Without the engine running, move the control lever to WOT and then look at the carb blades. The throttle stop screw should be adjusted so they are straight in line with the carb bore - not cocked at all. This should give you maximum air flow.<br /><br />While doing this, before any adjustments are made, I would simulate WOT then "If I back it off a little it runs fine." Just try to remember how much you backed off the throttle lever when you were out the last time, and try to duplicate that. Now look into the carb and see what the butterflys have done. This process may shed some light on your problem.<br /><br />Good Luck,<br /><br />Gold Bear

 

[dstuard]

Re: Mercury Ignition?

Rebuilt the carbs and took her out to the lake to find no improvement. Carbs were dirty though and needed it anyway. I did find in my frustration that the "T" (fuel line) between the #1 and #2 carbs leaked gas when I squeezed the bulb. Could this be my problem all together? I know I still have some adjusting to do but I hope I am close. Could this be a timing problem? Takes FOREVER to get on plane but when it does it runs pretty smooth up to full throttle. Also going to replace the zip ties with hose clamps. Hopefully this will help. Someone please tell me my T could be the problem so I will at least have hope.

 

[dstuard]

Re: Mercury Ignition?

^^^

 

[jim dozier]

Re: Mercury Ignition?

Leaky fuel hoses are never a good thing. You have hope. Get a new fuel hose and see what happens. Good luck.

 

[dstuard]

Re: Mercury Ignition?

Would it make it suck too much air? I would think that if there was gas in the carbs that it would at least run until it was all gone. Who knows. I would at least like to narrow it between a fuel and ignition problem. Is there a way to test the coils to see if one is breaking down under a load? I will pull the plugs today and see how they look. I tried new plugs but still the same problem. I still suspect the stator on the high side. Ohms were 700 over the specification. Is this far enough over to warrant a new stator?

 

[dstuard]

Re: Mercury Ignition?

Can someone tell me if my stator could be the problem? The ohms were 6900 red to blue and 6750 from red/white to blue/white. Specs say 4500-6200. My problem is a bogg in the hole and misses when I get past 3000 rpm.

 

[dstuard]

Re: Mercury Ignition?

Any ideas as to if my stator is bad? I tried the dva adapter and can't get a reading on my meter. Jumps around too fast.