1968 Merc 20hp Twin, underload won't go full power, out of the water it goes full power

Before I tear into*the carb I thought I would ask here first.

Had my Merc for 10+ yrs w/no problems.*Last*fall*I went into the shallows and tilted the motor up. When I came out and lowered it back down, it would not go full speed, maybe 5MPH. Been that way ever since, never had that happen before when I tilted the motor back. A friend told me maybe the rubber*fuel tank line or pump bulb had a crack and was sucking air. I replaced it and still no full power under load.

At home with the ears on it will advance to full speed power in forward, no problem whats so ever. But when its in the water under load same problem,*it*will only*run*a little faster than*idle speed. It doesn't spit or sputter like its missing either.

I talked to another buddy and he thought maybe when I tilted the motor back, maybe there was some dirt in the bottom of the float and it loosened when I tilted the motor and it got sucked up into*the jet nozzel, therefore loss of power.

I love my old vintage 68 Merc, don't want to replace it. Anyone have any ideas if anything else could be the problem. Since it runs perfect out of the water, I wouldn't think its electrical, has to be the fuel system.

I haven't really looked at it yet to see if there's a inline filter or if there's a screen filter behind the tank hose connect. That also might be the problem.

Hi Charly1954,

First,not a good idea to run it above 1500RPM's on the ears,could cause damage to the powerhead. It will run good on the ears as there is no load on,so takes little to get the RPM.s up.
My thoughts are as your buddy said,loosened some dirt in the carb,so a cleaning,and a blast of air trough the jets to be sure and shift any dirt.
Start at the tank,check for blockage at pick up,have the fuel lines ever been changed? Ethanol will break down the old rubber fuel lines,not a problem we have this side of the Atlantic...yet. Link to a schematics of your motor http://www.crowleymarine.com/mercury-outboard/parts/439_7.cfm .If you need to get parts,it helps to keep this site going if you get them here at marineengine.com.No filter unless you fit one yourself.

tks for that input, I appreciate it. I've had it 10+ yrs and never changed any part of the fuel system except the tank inline hose and primer bulb. So maybe its a hose inside, but I really think its a speck of dirt somewhere cloging something. Sometime in the next 2 wks I am hopeing to get into it. I probably will change all motor fuel lines and clean the carb. Any part I need I will surely check out marineengine.com. I know old motor parts can be hard to find.

tks again Charly

Hey charly1954 do spark check I'm guessing it's only running on 1cyl had the same problem on different engine

Is this single carb or multiple??

68 Mercury 20HP was just one carburetor !!!-----Sounds like the motor is running on one cylinder due to , no sprk on one cylinder / poor compression on one cylinder or a broken reed valve.-----Trouble shooting is how you go about solving a motor " mystery "

Agreed. Pull the plugs, ground them to the block, and wheel her over. You should see a nice blue spark at each plug or...

That's a Phelon magneto motor. If no spark, it could be dirty points, a bad coil or condensor.

Jeff

PS: No way is it a bad reed valve! Can we get off that kick? Blown reeds in old Mercs is very rare.

Seen lots of chipped broken reeds on outboards. Also debris stuck in reed valves. Therefor these things are a " no cost check " which is what I try to teach folks to do.-----------Trouble shooting is first and foremost in my book !!!!

racerone said:

Seen lots of chipped broken reeds on outboards. Also debris stuck in reed valves. Therefor these things are a " no cost check " which is what I try to teach folks to do.-----------Trouble shooting is first and foremost in my book !!!!

Click to expand...

Not sure what you are talking about here, whats a reed valve?

I was thinking I did check both plugs for spark, but I may not have so I'll do that again.

The one thing that sticks in my mind is pulling the motor back when I went into the shallows, thats exactly when it happened.

tks everyone for your help replies, I really appreciate them.

Visit ----You-tube------for a tutorial on the operation of a 2 stroke motor.-----Lots of info to help you understand how your motor works.-------Some videos are better that others.----search for 2 stroke principle , reed valves in 2 stroke .

It is time to refresh your memory !-------Under the flywheel you will find -----2 coils -----2 condensers -----2 sets of breaker points.-----------Should be an easy fix.

guyjg said:

http://www.seawaymarine.com/

Click to expand...

Could not find my motor at that site.

As I said earlier I could not find my motors parts on this site either. Since I got help from this site I wanted to order from this site, but if I can't find the part I can't order. On this site when I search for my serial number 2298982 it was not there, there was no SS numbers between 1592567 and 2827677. I also tried the "Find Mercury Parts by Engine Model" and had no luck.

If anyone can post a direct link from any parts site for my motor I would appreciate it. What I mean is a link where you already found my motor parts, not just a site link for me to seach thru.

This is all the info I have, the plate on my Mercury says Kiekhaefer Mercury Serial # 2298982, its a 1968 Merc200 20hp with I think the short shaft. I was wanting to get it working right before my grandson comes up from Florida next week. I guess I can always just use the trolling motor on a small lake.


EDITED:

I am thinking that since I couldn't find my Serial number, then this site doesn't have the ignition parts I may need. 40+ yr old parts are hard to come by so I searched online and found laingsoutboards. They have the condenser and coil but no points. The coil is pretty salty at $80, but can't be picky when they're hard to find.

tks all for your input and help, I appreciate it.
Charly

Are the points that bad so you can't reuse them? Try calling the site I posted.

Not got the flywheel off yet. I'm probably being to carefull when cranking turns on the puller, hard to find and expensive to replace if damaged.

My puller has wide bolt slots, the bolts that came with it are to big so I got right sized bolts and put a washer on and the washers bent down into the slots. So i went and got longer bolts and heavier wider washers. It was dark when I got home so I sprayed a small amount of liquid wrench to set over night, my WD40 can was empty,grrrr....

Here's a dumb question, but one never knows until they ask. I am 99.9% sure I am not suppose to take the hub w/ 8 bolts off, right? I did take 2 bolts out since there was no holes for the puller bolts, left the rest in. But by the looks of the rubed off red paint, those 8 bolts have been off a few times by someone else.

Now when I get the flywheel off the first thing I'm going to check is the coil, I really feel thats the problem. I do have a multi-meter. To check the coils primary and secondary wires I set the meter to resistance(ohms) 2000K, is that right? Then check the large wire from coil to points, then coil ground to spark plug wire end. Then I'll check for burnt or dirty points, emery cloth them if they are still ok. For the condenser I check it like the coil right?

I am hopeing this weekend I find out what I need to replace and get them ordered, so I can get parts in it to take my grandson fishing, he'll be up for 2 wks.

I am no mechanic but I can tear into the older simpler motors, the new modern stuff I wouldn't attempt it.

Don't pull the flywheel by removing the 8 bolts. The whole works should come off but, if it's being stubborn, try rapping on the puller bolt with a solid hammer blow--that helps.

The most likely cause of no spark is dirty points. Remove them both and sand the surfaces with 400 sandpaper followed by a good solvent cleaning with "cut finder" (AKA: lacquer thinner). Then slip the flywheel back on and see if there's spark. I use an electric drill for this,with a simple scket adapter from Harbor Freight (and other suppliers. Do NOT tighten down the nut down or you'll have to get the puller out again.) Obviously the plugs are out while doing this and grounded to the block.

If still no spark--and you're positive the points are set correctly, and that the insulating washers on the points are doing their job--then it's condensor time. Assuming the top cylinder still has spark, swap the condensors and see if the lower now works. If so, replace the condensors (both of them). If no spark the coil may be shot.

I've see a few, older Phelon coils give up of late, but they still made spark--they wouldn't run the motor, however.

Jeff

got the flywheel off tonight. I first checked the coil with the meter.
I had it set on Ohms 2000K, the readout was 1.
Upper cylinder(had spark)
I touched probes to Coil grnd & points termial it read 0
I touched probes to coil grnd & spark plug end it read 16
Lower cylinder(had no spark)
I touched probes to Coil grnd & points termial it read 0
I touched probes to coil grnd & spark plug end it read 26

No idea why or what the different reading mean on the coil/plug end, other than maybe the 26 reading means its no good.

Then I checked the points, not burnt or damaged so I cleaned them like I do any points. I run some emery cloth thru them while they where closed then whiped them clean. Then I swaped condensers, when I did that I found the coil wire terminal on the lower cylinder coil looked different than on the upper. I don't think it should make a differance but I took a photo of it, heres the photo link http://pic100.picturetrail.com/VOL895/13493543/24122677/402957342.jpg. The other coils terminal is closed, this one looks like someone replaced it and had cut it and spread it open so it would slide over the screw. Put it all back together and same thing, upper cylinder had spark lower didn't. So its not the condenser or points, must be the coil or plug wire.

Another dumb question. I didn't take the coil off so no idea if the plug wire goes into the coil or connects to it. If it connects maybe I should of taken the coil off and checked where the plug wire connects. It was dark so I quit, tackle it more tommorrow.

The coil wire just pokes into the coil. You might pull the coil and see if it's making good contact inside there.

Jeff

fastjeff said:

The coil wire just pokes into the coil. You might pull the coil and see if it's making good contact inside there.

Jeff

Click to expand...

I finally had time to pull the flywheel tonight. The ground and points wires are sealed right into the sealed coil, no way to check wires going into the coil. But when I pulled the coil off the plug wire pulled right out. I looked up into the coil and seen a screw so the plug wire must just screw up into the coil, is that right?

The plug wire end looked frayed so I cut about 1/4" off and screwed it back up into the coil. Put it all back togther, with hopes that was the problem. Nope, still no spark on lower cylinder. Maybe it was possible when I screwed the plug wire up into the coil it didn't make contact. So I think I will just pull the coil off again and take it somewhere like a small engine repair shop and ask them to test it, if they can. I really don't want to spend the $70-80 for a coil if the plug wire is the problem....

BTW, if I do get a new coil, the ones I see have no plug wires attached. How do I attach the plug wire, do all the late model ones have a screw in the coil where you screw the plug wire up into? Can I take a normal car plug wire and use it? Or is outboard motors different since they are pull start and not 12V.

ALso, I expected the plug wire to have a wire center, it looked like fiber, there was no wire core.

Your coil and wire sounds okay (and that's what it is supposed to look like).

Pull the points for that cylinder and sand the faces with 400 sandpaper until they are clean and flat. Run a clean cloth through them, then reassemble and set them at 0.020 " on the high spot of the cam. Then--plugs out--put the flywheel back on loosely and rope it over to check for spark. If none, swap the condensors and try again.

Jeff

After I thought about it, I think maybe what happened is when I pulled the coil off I pulled the plug wire out of the coil. The plug wire was straped down and there was no give so by prying the coil off I probably pulled the wire out of the coil. I already swaped the condensers and still no spark on the lower cylinder, so the condensers are ok. I also used my multimeter and checked the points, both tested "0" resistance. I also cleaned the points, they was not dirty, burnt, or pited. So I am about 99% sure its the coil or plug wire. My last resort before I order a new coil. Is take the coil with plug wire out and have someone check it to be 100% sure its either the coil or plug wire.

One thing that puzzles me is the lower cylender coil and wire look original, but the plug wire doesn't have a wire core. I would think back in the late 60's the plug wire would be wire core. So another thought, I think I will take a get a new plug wire, attach it to the coil and see what happens. If no lower cylinder spark then it has to be the coil.

tks again for all the tips, I appreciate them.