How do I do a resistance check on a coil?

[Redbarron]

Hi everyone, I have a 1968 Johnson 100hp Outboard, at least I am told its a 68, here are the numbers<br /><br />Mod V4TL-14B<br />SER J2988985<br /><br /> I want to check the coil, I know there is a way to test the resistance using a Ohmeter, just not sure what terminals to check and what the reading should be for a coil.<br /><br />It looks like a car coil, just a little shorter, has the standard positive and negitive terms and the coil wire.<br /><br />The guy I got the boat and motor from had no spark when he got it, I had found he had a negitive wire on the positive side of the coil, motor fired then, now he says no spark again, but he had so many wires unplugged it was not funny, I am planning to reconnect and try it and go from there, so if anyone can help with the specs on a coil test, I would appreciate it.<br /><br />Thanks<br />Rick

 

[Trent]

Re: How do I do a resistance check on a coil?

Make sure you have at least 9.5 volts to the pack during starting, or you will not get any fire to the plugs. Also make sure your engine is turning over at "full cranking speed". A dragging stater will keep it from starting. web page

 

[jhreed]

Re: How do I do a resistance check on a coil?

goofed

 

[jhreed]

Re: How do I do a resistance check on a coil?

In my limited past, I've found that the resistance from + to - has generally been in the very low ohms like 0.5 to 2 ohms. If one measures from the plug terminal on top of the coil, they might get anywhere from 1000 ohms to <br />15000 ohms to either the + or the - terminal. <br /> Hope this helps.. jr.

 

[rexa1925]

Re: How do I do a resistance check on a coil?

Coils that use a ballast resistors should have<br />about 1.0 ohm to 4.0 ohm.<br />If you get above 7.0 ohm I would think twice about<br />it.<br />Just put the jumper wires on the two terminals.<br />to check the primary. 90% of time that where<br />it will go bad at, sometime the secondary but not<br />to often.<br />You can put the wire jumper on the terminal to<br />the dist. and put the other in the main coil hole<br />to check for a dead short and the other terminal<br />the same way.<br />You touch the outside of the coil too to see<br />if you got a dead short but then the first check<br />should show open.<br />Good luck<br />Rex A. H.<br />My number is 3744 I don't know where this other<br />numger came from??????????????????????????????

 

[Rex]

Re: How do I do a resistance check on a coil?

Will I found it I guess I have 2 number.<br />It's just how I login I think.<br />Anyway good luck<br />Rex

 

[Rex]

Re: How do I do a resistance check on a coil?

How did your check out.<br />Rex A.

 

[Redbarron]

Re: How do I do a resistance check on a coil?

Thanks, I will check it out, the coil has visable cracks in the top, sorry for the delay in the reply, I didn't think I was getting any posts, I didn't recieve any emails saying there was a reply, I guess I need to check my account settings.<br /><br />The guy I got the boat from only had it a few months, he was suppose to buy it from a coworker on payments and couldn't pay for it, I found alot of stuff unhooked, He had said once he suspected the power pack, but I have heard it run not to long ago. I want to eliminate the other possible causes first, like I said when he got the boat he had a ground wire attached to the positive side of the coil, it fired after I put the wire in the right place, then he said one day it ran for a few minutes and quit again. what else should I check, I am also going to check the key switch for a grounded kill wire.<br /><br />Thanks guys, I will let you know, I am having a hard time finding enough daylight after work to check it to well.<br /><br />Rick

 

[scotiany]

Re: How do I do a resistance check on a coil?

I don't know if this belongs in this thread but here goes. How does one check a magneto type coil? I've got the Chrysler manual and all it says is primary winding resistance should be .6 ohms and the secondary winding resistance should be 5900 ohms.

 

[Rex]

Re: How do I do a resistance check on a coil?

I think you check it the same way not sure.<br />Rex A. H.

 

[Redbarron]

Re: How do I do a resistance check on a coil?

Oh my gosh, well, I found an obvious problem, the coil wire is not connected to the distributer, it looks like it got pulled on, it is pulled right off the connecter itself, so it looks like I am going to be removing the flywheel to try and get to the distributer, hopefully, I can replace it without replacing the distributer.<br /><br />I will let ya know

 

[Redbarron]

Re: How do I do a resistance check on a coil?

Ok, here is what I have found, I have removed what I think must be like a distributer cap, all the wires from the plugs plug into it.<br /><br />where the coil wire went, it is broken, the end of the wire is still attached and it appears someone tried to pull it with pliers and broke a piece of plastic off where the wire boot slides on.<br /><br />anyway, I have removed all the plug wires and the distributer thing which also has attached to it the round thing with all the wire wraps, sorry, I don't know what these things are called, please help, I want to know where I can get them so I can find out how much they are.<br /><br />Thanks<br />Rick

 

[Hooty]

Re: How do I do a resistance check on a coil?

Redbarron,<br />You're gonna be time and money ahead if you'll get a manual for that thing before you start working on it.<br /><br />c/6<br /><br />Hooty

 

[Redbarron]

Re: How do I do a resistance check on a coil?

Thanks, I am already planning on getting the manual.