1973 18 hp evinrude Driver Coil test

[KC9000]

Hello new to the forum, I have a 1973 18 hp Evinrude rope start, I am giving it a tune up and wanted to know if I am testing the driver coil correctly. If so this would be a bad coil. According to an older post I have looked at with info on how to test it, "Connect coil leads to an ohm meter set to low ohms scale. Coil is good if resistance checks 1.45 + /- .4 ohms (rope start model) , or 2.70 +/- .7 ohms ( electric start model)." There is also fuel mix all over the parts in the magneto and I will be putting in a new crankshaft seal, but would that help kill the coil or make it test low resistance?

 

[F_R]

Your test procedure is correct. But I can't vouch for the specifications you presented.

 

[KC9000]

Yeah I'm such a novice at this and do not have a manual for this motor... I think that would be a good investment. Thanks for confirming the procedure I appreciate it. If any one can confirm the specs of the driver coil resistance for this 1973 18 hp evinrude rope start, that would be great.

 

[gm280]

A couple things to do first. Clean the exciter coil up and dry it off. Then touch both leads of the meter leads together while on the lowest ohms scale setting and verify the reading first. Because your meter could be reading off some and therefore the exciter coil could be just find. Also touch one meter lead to either end of the exciter coil and the other meter lead to the metal. If you get any reading doing that, other then open, buy a new coil. But if that doesn't read anything, I would test run the engine with that coil myself. JMHO

 

[KC9000]

The motor runs great, 120/120 compression, idles a bit rough and had a lean sneeze type issue, thats when I noticed the top external coil was toast, it shocked me too, replaced that, took it out fishing and we hit 21 mph with it. She is a bit hard to start like maybe 5 to 7 good pulls, I noticed that when we ran at WOT for a few miles and then turn her down to idle it would lean sneeze or miss not to sure which it is, im still pretty green in this department but eager to learn new stuff. But upon throttle down to idle speed it would sneeze/miss, I adjusted the low speed needle to run richer and that seemed to take care of it and that makes me think lean sneeze. I knew the magneto had mix all over cause you could see it under and in that area so now just gonna replace the top crankshaft seal, points, and condenser. Want to make sure that driver coil was good to go. GM280 With your advice about the multimeter reading wrong I think you were right on the money . Tested with 3 meters. Went through this baby from bottom to top and almost done. Great learning adventure.

 

[KC9000]

That green meter is +/- 1.2 % + 5, so with that .7 reading that should be with in that 1.45 +/- .4, specification if that is correct, that spec was from a 76 rude, I have a 73, but I think they are very similar.

 

[oldboat1]

Why not simply measure output if the motor is running. Measure open air spark on each lead.

 

[Faztbullet]

The hard start,miss, sneeze is lean from crankcase seal...

 

[KC9000]

Oldboat 1, that is a good idea, me being green did not think of that before taking it apart... . Faztbullet, great advice too. Thank you guys big time. I will measure that open air spark when I reassemble. Can't wait, hopefully she purrs like a kitten after the tune up. I'll up date when done. Here's a pic of the magneto when I took the flywheel off.

 

[racerone]

Those driver coils are very reliable.----Funny that they would list different values for electric start.----Parts book seems to show one part # as a replacement.

 

[hardwater fisherman]

Those driver coils are very reliable.----Funny that they would list different values for electric start.----Parts book seems to show one part # as a replacement

The ohm values listed are the same as per my service manual for a 1976 40 hp. My motor uses 2 different driver coils. 1 for electric and 1 for rope start. And you are right that the 18 hp has only 1 part number. And that part number is different then both the numbers of the 40 hp.

 

[KC9000]

Sweet, I really appreciate the feedback, this helps ease the OCD in me. Trying to be as thorough as possible.

 

[KC9000]

So I tested the driver coil and it seems to be good. Put new points, condensers, top crankshaft seal. Gapped points to .020, I am gonna buy a timing fixture and do the timing again later, but for now it works and it started easier.
Here is a video after putting it back together, no lean sneeze, but I think it can run better....any input will help, I am gonna order the timing tool, but for now this is what I got.

 

[racerone]

You need more water in that test bucket.---Water must be 6"or 8 " above the pump.--------The timing tool is nothing but a " dummy flywheel "----So you can use the flywheel you have.----Just takes a little longer.

 

[KC9000]

Yeah, the bottom of that bucket broke in that video, I am gonna get a stand and a better bucket. I broke all 3 of them . But that's good to know about the tool, the mark on the flywheel, is this it the mark above the two lines on the armature plate, one on each side right. How would one get the multimeter probe / clip to the point, or could one use the spark plug wire that comes from the plate and the ground to the armature plate? Of course pull the flywheel to make sure I got the correct side.

 

[racerone]

You lock the magneto plate so it does not turn.----Full throttle or lowest idle.----The position DOES NOT matter.----Turn flywheel till mark lines up.----Lift off the flywheel and set points with the meter.-----Have not done one in a while but I believe on these the points at the rear are set for top cylinder.

 

[KC9000]

Awesome I will do this, some time this week and let you know how it went, thanks again for the advice it is greatly appreciated.

 

[oldboat1]

To my ear, it runs pretty well. Think I would put it on a boat and run it -- tweak the idle adjustment after a good run or two.

 

[KC9000]

Yeah, had plans on taking it out this weekend, but fam wants to go do something so it will have to wait til next weekend, maybe Sunday morning tho we will see. I'll let you know how it goes either way. Thank you for the input, I'm still green at this, but learning a lot of valuable info. Thanks again.

 

[KC9000]

It is running like a champ, 20 mph in a little chop, one pull to start. Very strong motor. On to the next one. I have a 20 hp Mariner that has no spark, but I will start a new topic for that one. Testing all ignition parts now.