Reversed polarity

I have this friend... he hooked up his 1960 Evinrude Lark II 40hp battery backwards. What a bonehead move right! Anyway, here is the situation. The motor ran with the polarity reversed. It stalled a few times, but generally ran pretty well. Gas was low so a run to the gas station and back to the boat. The engine ran again for a bit, but then finally would not restart. I got the boat home for some diagnostic work and that is when I found that the battery was connected backwards. I reconnected the battery correctly and the engine will turn over but it will not start. I checked the spark and it seems good. The starter is having a difficult time turning over though. There doesn't seem to be any blown fuses anywhere and nothing smelled or looks like it was burned. I have been searching around the forums for some clues and found information about a rectifier and the stator. I haven't been able to locate the rectifier on my engine yet. If the stator is ruined, does that mean replacing it? What are the most likely things that need replacing. Thanks for any advice! BTW, I'm the bonehead that connected the battery backwards - but if we can keep that between us it would make me feel better

It certainly does not have a rectifier.--------The electrical system was very simple on those.-------------There also is no stator as in newer motors.--------Does it have the optional belt driven generator??------------The battery is only used to turn the motor over for starting.---The magneto is a self contained unit and produces spark independent of the battery.

The 1960hp 40hp model does not have an alternator and therefore does not have a rectifier, diodes, etc. Hooking the battery up backwards would not have any bearing on the engines running performance, nor will it damage anything or cause the engine not to run.

The 1960 model is the very first 40hp OMC engine to be manufactured, has standard shift, no generator, with magneto ignition.... about as simple as it can get.

The battery is used simply to crank the engine over via the electric starter, after which the battery is not connected electrically to the engine in any manner.... the engine's ignition is a magneto system.

Your problem is elsewhere.... water in the fuel, raw oil in the carburetor due to putting oil first into a empty tank, weak or no spark, fouled carburetor, broken fuel pump diaphragm, something of that nature.

Ok, so hooking the battery up backwards on my model did no damage? That is good to hear and a relief. I'll go do a little more diagnosis and see what I can come up with. The fuel is new and oil added after tank was full. I am wondering if it is something to do with my wiring harness and cutoff switch. The wiring harness that I have is old and not in great shape. I cleaned it up the best that I could and rewired what I could. There is a wire from the wiring harness that connects to the cutoff switch. It broke and so I rewired it (again). The engine was running before this breakage and I don't think that it has run since. This seems to be an obvious next item to check, but I am not sure what that wire does or how to check it's integrity. Is that the wire that is connected to the ignition key that allows you to turn the engine off?

There is no way that we can say what wire is leading to what on that engine without actually being there.

However, there will be two black wires leading down from the armatiure plate (plate with points etc) which are connected to the points. When these wires are connected together (points connected), the ignition is shorted out.... and when they are not connected, the ignition is in effect. You would need to trace whatever wires are connected to these black wires with an ohm meter in order to determine if they should be connected to a stop button, ign switch, whatever.

NOTE.... Best to put in a couple gallons of fuel, then add the oil, then top off with the remaining amount of fuel.

Is it possible that the ignition switch is the culprit? At one point, the engine would start, but would not turn off by the key. Can I by-pass the wiring harness and cut-off switch (safety switch too) by disconnecting the wiring harness and starting the engine by connecting directly to the battery. I just have a feeling that the problem is related to something electrical. I'm still not great using a multimeter to diagnose problems but I am learning. I also wonder if the engine is getting a weak ground. How is the ground checked?

Someone correct me if I'm wrong, but isn't a DC motor (starter) polarity sensitive? In other words if you reverse polarity the motor (starter) would spin in the opposite direction, no? If the starter is spinning backwards how could it start the motor, the starter drive gear wouldn't even engage the flywheel would it?

The old starter mtrs that had field coils in them will not spin backwards. The newer ones with magnets for field coils will. To change the rotation of the ones with field coils you have to reposition the armature plate.

This is perfect, best wiring diagram I have found for my engine yet! Thanks. I still suspect something electrical and finding the problem will be my weekend project. BTW, the starter is connected to the positive post with a 3 gauge wire. I don't see a wire for the negative so I assume that the starter is grounded by virtue of being attached to the motor head with a metal bracket. What is providing the ground to the motor head in the first place? It appears that a black wire from the wiring harness attaching... I 'm not sure where? Should I be able to use a multimeter set to continuity, one lead to negative terminal on battery and one lead to black wire(s) from wiring harness and then follow that wire to it's connection? The multimeter will read non-zero, but value greater than 1 then I'm good to go? Am I on the right track?

Update... I took the starter to my starter guy and sure enough, by reversing the polarity on the battery I blew out part of the armature. He said that he could tell what was wrong as soon as I brought it to him. He fixed it for nothing b/c he said that a man that tells the truth about messing up by connecting the battery backwards deserved a break. I guess this is why my mama taught me never to lie The starter turns well now. I seem to be getting good spark from both plugs but I still can't get it started. Spraying starting fluid in the carb won't even get it to catch. I must have a fuel problem now, but not sure how to diagnose it exactly. Back to the Seloc manual!

Trust me (as the carney guy said)... Reverse polarity cannot damage the electric starter armature. Armature failure is encountered by cranking the engine longer than 20 seconds as is the recommneded maximum time allowed to operate the starter. Exceeding that time runs the risk of overheating the starter's armature, solder melting, etc (armature failure) but no matter... hopefully it holds up for you.

Time to start over....

Spark plugs removed.... Check the compression. What are the psi readings?

Spark plugs still removed.... The spark must jump a 1/4" to 3/8" gap with a strong blue lightning like flame... a real SNAP! Does it? The gap is important... check spark by using the spark plugs is a waste of time.

Remove the flywheel and check the flywheel key to see if it sheared (out of time). If it's sheared, replace it with the special required 307480 key. DO NOT attempt to replace it with some hardware store key! NOTE that the flywheel nut must be torqued to 105 foot pounds... anything less will cause the key to shear again.

The key must be installed with the straight outside edge being straight up and down in line with the engine itself... NOT with the crankshaft taper!

Spark plugs should be Champion J4C or J6C plugs gapped at .030 . Due to the engine's age, the J6C might be the best choice.

Now.... if all the above is as it should be and the engine will not start, the usual cause is a fouled carburetor.

Agree + 1 with the above. Reversing starter mtr polarity will not damage it. Listen to the rest of what Joe said as far as trouble shooting the mtr.

I worked a couple of hours on it this afternoon and it cranks good now, but it still wont fire. I checked the spark plugs with a tester and could see good spark. I also tested plug by grounding it against a powerhead nut and got a good spark there too. I didn't try testing to see if the plug would jump a 1/4" gap. I checked the compression and got 100 in both cylinders. I only had one plug out at a time for this test so I'll try it again with both plugs out as your message says. I'll re-gap the plugs while I'm at it. I had the flywheel off yesterday and the flywheel key was ok but I'm gonna check it again along with the other things your recommend tomorrow. The Seloc manual says that the low speed needle should be seated and backed out 1.5 turns. The high speed needle should be backed out 3/4 of a turn. Does this sounds about right? I just don't understand why with good spark (I think good spark) the engine won't fire after spraying starting fluid directly into carb? Does this make sense in any scenario? Thanks for your help! This is like a puzzle (that for me isn't solvable right now). I'm having fun trying though!

Checking the spark with the plugs tells you nothing !! As I said, listen to Joe.

If no spark tester is available..................

A number two (#2) medium philips screwdriver can be inserted within the spring clip inside the rubber spark plug boot (the #2 philips screwdriver fits perfectly). The shank of the screwdriver can then be held away from the powerhead approximately that 7/16" distance for a proper spark test.

(Carburetor Adjustments - Two Adjustable N/Vs)
(J. Reeves)

Initial settings are: Bottom high speed = seat gently, then open 1 turn out. Top slow speed = seat gently, then open 1-1/2 turns.

Setting the high and low needle valves properly:

NOTE: For engines that DO NOT have a shift selection, obviously there is no NEUTRAL position. Simply lower the rpms to the lowest setting to obtain the low speed needle valve adjustment.

(High Speed) Start engine (it will run pretty rough), shift into forward gear, take up to full throttle. In segments of 1/8 turn, waiting for the engine to respond between turns, start turning in the bottom high speed needle valve. You'll reach a point whereas the engine will either start to die out or spit back (sounds like a mild backfire). At that point, back out the needle valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest setting.

(Low Speed) Slow the engine down to where it just stays running. Shift into neutral. Again in segments of 1/8 turns, start to turn the top needle valve in. Wait a few seconds for the engine to respond. As you turn the valve in, the rpms will increase. Lower the rpms again to where the engine will just stay running. Eventually you'll hit the point where the engine wants to die out or it will spit back. Again, at that point, back out the valve 1/4 turn. Within that 1/4 turn, you'll find the smoothest slow speed setting.

When you have finished the above adjustments, you will have no reason to move them again unless the carburetor fouls/gums up from sitting, in which case you would be required to remove, clean, and rebuild the carburetor anyway.

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I took the carb off today and took it apart (I rebuilt it a few months ago), and it was clean. None of the jets were blocked and I didn't see any crud in the bowl. I blew air though all the openings just to make sure nothing was stuck someplace I couldn't see. As it turns out I found a mistake that I made when I rebuilt it. I forgot to put the gasket in around the base of the main jet. I'm not sure what effect this had, but it didn't seem to make a difference with the engine not firing. I took off the fuel pump and took it apart. I haven't rebuilt it, but it seemed clean as a whistle and the diaphragm was in good shape. I could rebuild the fuel pump, but I doubt it is my problem. I am getting a spark and I tested that again today, but when I crank the engine it just doesn't want to fire. Our discussion above makes me wonder. Is there a circumstance where there is spark, but its just not strong enough? The spark plugs are new and gapped correctly. The coil, condenser and points are fairly new. Then I remembered... I had the engine in for some work last summer and the mechanic said that he was getting a short on the armature plate, but wasn't sure why. He put new points and condensers in and the problem when away. I also read another thread somewhere else and the guy with a similar engine to mine with a similar problem mentioned that he covered the spot where the spark plug wire attaches to the coil with that heat shrink wrap stuff and his problem went away. Can you test coil, condenser, points or is it just easier to replace them? Would any of this be related to reversing the polarity (where this thread began) or is it just a coincidence?

Folks still test with the plugs I guess.-----------They refuse to believe that a proper spark test is a gap of 1/4" or more.---------So set something up that gives you that gap.-You can use 2 pieces of plug wire staple to plywood or whatever.--------Test and see if the ignition will jump a gap of 1/4" or more.---It it can not do that then essentially you have " NO SPARK " when the air is compressed in the cylinder.-----12 volts is not used by the ignition to generate the spark at the plugs.

I think I've explained as thoroughly and simply as possible and can add nothing further. Good luck.

Ok, got it. I have some things to try and it appears that I just have one or 2 of the fundamentals wrong right now. I'll go back over my work on the ignition system, and I am going to rebuild the fuel pump just to rule it out of the equation. (its a good time of year for this type of work I guess). Thanks again for your help, you all of given me a much better idea of how to diagnose engine problems. I'll update this thread again when I have more to report, hopefully with good news!

I rebuilt the fuel pump and I'm still in a no-start situation. After doing some more troubleshooting I found out that the polarity for the bottom cylinder coil is reversed. The polarity for the top cylinder coil is correct. I removed the flywheel and noticed that the cam follower was not engaging the cam at the right place so I adjusted that. The top coil's boot was split so I replaced that. Is the bottom coil bad since it's polarity is reverse? How could it even become reversed in the first place? Its not like you can hook the wires up in the wrong place. Thanks for any ideas.

Bart Hanline said:

I found out that the polarity for the bottom cylinder coil is reversed. The polarity for the top cylinder coil is correct.

Click to expand...

Polarity at the spark plug boots?

Yes, I followed the troubleshooting steps in the Seloc manual for my engine and the polarity (at the boot) for the bottom coil is reversed. You probably have seen this before but Seloc (if you don't have a voltmeter) recommends using a pencil in between the spark plug wire (take boot off to get to metal connector) and the spark plug. If the spark feathers toward the plug you are in good shape. If the spark feathers toward the spark plug wire then the polarity is reversed. The seloc manual implies this is bad, but doesn't tell you how to fix it. I could get another coil, but I am skeptical that would make a difference since the new coil would be installed the same way.

SELOC manuals are known to be full of nonsense and mistakes !!

Just to close this thread. My engine is up and running and all it needs at this point is some tuning on the carb. I replaced all the ignition electronics, and some of the wiring. I still had a no start situation and finally decided to disconnect the safety switch that is attached to the throttle. It started. I think that the issue was a bad switch all along, it just so happened it occurred at the same time I reversed the polarity on the battery. My lesson... believe your own diagnostics and move on to the next logical check. I knew that I had good compression, I knew that I was getting good spark and I knew that fuel was flowing. It just took me too long to figure out that it was the safety switch. Thanks to everyone who contributed to this thread!