1973 evinrude 25hp wont idle

[hardwater fisherman]

Personally I think for that ignition system a 1/4 inch or 5/16 should be ok. That is to say that if the spark is a good snap.I have a 40hp with the same ignition that I was chasing a no spark at cranking speed on the bottom. I kind of gave up on it last year but I now got it running well again. And I am not sure what I did other then clean the points and clean all connections. I also ran all new wires from the points to the coils. It still has stronger spark on top but it seems to be running well. For your driver coil my manual says that if it fails then you will have zero spark on both. So if you have any spark at all on either than it is probably not the driver coil. In a earlier post you said something about not pushing the plug wires in far enough into the coils. If they are anything like mine you need to turn them while pushing, To check spark i put a long screw driver bit from a cordless drill inside the plug boot and hold it with insulated pliers and see how far it can jump. Yours being a pull start you could maybe have someone help you.

 

[brsoo]

The plug wires are making good contact. It will not jump 7/16. But it has a white decently thick spark at 1/4". I did rebuild a the fuel pump which is not supposed to be rebuilt. Would air in the fuel or not enough fuel make it bog down and run poor?

 

[brsoo]

I just tested again in a pitch dark room. No spark jump bigger than 1/4. The top coil is stronger than my bottom.
Hardwater fisherman
Have you ever tested the coils to see a ohm reading? Mine are both at 4500 ohm? Could they both just be weak from use? Id think they would have different readings if they where bad tho?

 

[Bosunsmate]

If you a getting only a 1/4 with plugs out and LU dropped it would make me think somethings not right, but i dont have this motor

 

[hardwater fisherman]

I never noticed before but in the manual it does say set gap tester at 7/16 as Bosunsmate said. In my experience with these magnetos that might be a little hopeful. Either way you said you have a white spark of only 1/4 inch. The spark should be a strong BLUE snap..As far as the coils go the manual says primary [low ohms] 1.35 plus or minus 0.3 that is between the blue wire and the black. And secondary [high ohms] 13500 plus or minus 1500. That is between the spark plug lead and the black. I tested 3 coils that provide good spark. On a cheap digital meter set at 200k ohms and got numbers ranging from 11.8 and 13.2. The 11.8 might be a little low but that is on the top plug that gives a better spark so it should be okay. The manual says to remove them for testing to avoid a shock. I did check to make sure and the coils listed for your motor are the same part number as mine so the info in the manual should apply. Speaking of manuals you should find one for your own reference. There is a few for sale right now on Ebay. If you wish to check the driver coil. The manual says to remove both leads from the points. On low ohms scale check between the 2 point leads. Specs are 1.45 plus or minus 0.4. With the leads still disconnected and on high ohms scale check between point lead and ground. Infinity reading indicates a good driver coil. Any or zero reading indicates leads or driver coil is shorted to ground and should be replaced. Hope this helps.

 

[hardwater fisherman]

There are some videos on youtube that instruct how to set points with a multi meter. This will make the points open and close exactly 180 degrees apart.Also make sure the points are not dull or pitted and very clean.

 

[brsoo]

No Title

Hardwater fisherman thank you! I could not find any info online for the range. I went back and double checked my testing. I'm testing on a 1k scale and its actually just under the 4. Which would suggest it is around 380 ohm? So I'm probably testing the same bad result because your supposed to test on a much higher scale?? I thought since they both read the same that they where likely good. I read from on person they should test 3500-6500 and I thought I had 4500.. Now I'm thinking I have 380, right?? I do have a repair manual but its old and doesn't talk about the coils range.

 

[brsoo]

I went and bought a proper meter because I couldn't handle not knowing 100%
On 200k ohm scale I got 6.1 and 6.0 on the secondary. I'm now thinking this is the problem..
Would y'all agree?

 

[hardwater fisherman]

Sorry I am not very experienced when it comes to using multi meters and I am just relaying what it says in my manual. If you ask me it is not likely both coils would fail at the same time. The 2 coils I have on my motor are cracked and original to the motor.

 

[Bosunsmate]

I agree with Hardwater, you could put your new meter to use testing the upstream components such as the stator/charge coils but ive no idea what the reading wshould be.
CDI electronics if you look them up on the internet have an excellent troubleshooting guide for all motors individually, they instruct how to use a multimeter to test many of the functions, its what i always refer myself back too. The resistance testing of a stator/charge coil and checking it isnt leaking to ground is a simple but useful test that they explain

 

[Bosunsmate]

http://www.cdielectronics.com/troubleshootingguide/
Here it is, you should find accurate info in there about testing the ignition system on that 25hp 1973.
They explain things very simply and how to use your meter tester

 

[hardwater fisherman]

I just tested a coil that I know is not good and it gives no reading at all.

 

[hardwater fisherman]

Just to add the dead coil gives no reading on 200k ohms. But on 2000k ohms the good coil reads 013 and the bad coil reads much higher higher 1900 plus and the meter jumps up and down and never gives a stable reading.

 

[brsoo]

The cdi site did not have my specific motor in the help section. The similar motors didn't make much sense to me on their scales for testing.
From what I previously read ~13 ohm was tested on a good coil that is the same part #. And I test 6 ohm on mine the same way. I believe that is hard evidence.
I don't know enough about electrical systems either but the fact that I had a different reading seemed good enough?
I went a head and bought some new ones. I will test this and get back to you... Wish me luck!

 

[Bosunsmate]

It never hurts much having spare coils around, some people even take them out on the boat so hopefully they fix your strife

 

[brsoo]

I bought 581-124 coils and they test 6.8 on a 200k ohm scale. Not much difference. I wish someone had these exact coils. I doubt I have 4 newish coils all testing too low... This leaves me back to where I started. I will rebuild the lower. Install new coils then try it. I have new j6c plugs instead of j8c plugs. But I also doubt that matters

 

[brsoo]

So I'm putting in the seals for the lower unit and the prop seal was next to impossible to get out. Once out I installed the new one and the washer behind it. Now it doesn't hardly want to go on the shaft. I can turn the gears by hand but just barely. Its very tough to turn... Its like I dented the brass surface to where it create too much friction. I assume after running and going in gear the brass will just heat up and go back to shape.
Do y'all think I'm doomed? I can use another piece and order a new seal. But I don't want to do this again...

 

[Bosunsmate]

some tightness is expected, i normally end up giving things a try myself before resorting to having to order parts

 

[just_james]

It never hurts much having spare coils around, some people even take them out on the boat so hopefully they fix your strife

Bosunsmate, lol, I was one of this people when I had a 58 Fastwin. Had extra everything coils,points, plugs and flywheel keys.

 

[brsoo]

No Title

Ok so I moved it by hand and tapped the prop shaft with a hammer. It seemed to unstick whatever it was binding.. I read afterwards that there is a pin in the "bearing front assembly". I found the one in the gear head assembly and put it in place.. But not the bearing front. What damage will that do?? I put it back together really well and filled with lube anyways. The bearing front didn't seem to have a slot on the '73....???