15 hp Force 1984 no fire.

[RandyJ]

Model 152F4A SN 1127... from what I can find out this is a 1984 engine. Before I throw away a pocket full of money on this nice looking motor I thought I'd get an opinion. It is not firing at all. The points look great. Not sure how to check a condenser. I went by the book to check the coils. When I checked the ohms between the two little wires (primary and ground) I got like .004 ohm or therabouts on both coils. My Seloc manual says I'm supposed to get between .7 and .9 ohm. When I checked between the sparkplug wire and ground I got 7 ohms rather than the 7,000 to 17,000 ohms as in the book... the same on both coils ... I find it difficult to believe that I have the exact same readings for two bad coils. The only cheap way to check is to replace the condensers for less than $20. Well, guys, how do I check the coils on this thing?

 

[eurolarva]

Re: 15 hp Force 1984 no fire.

You must have a pretty acurate ohm meter. Typically on a wire your going to see .3 to .4 ohms of resistance. Take the meter off of auto and select the lowest ohm range to test the primary. When testing the secondary flip it to K ohms or 20Kohm range and test the secondary. When you tested were the wires disconnected on the coils? If not you may be getting a short from a plug wire with bad insulation. Also make sure the meter is set to ohms and not volts. That low reading sounds more like you are on voltage instead of ohms.

 

[RandyJ]

Re: 15 hp Force 1984 no fire.

Thanks. It is a cheap digital VOM and I typically use it only to check for continuity... might have to barrow my son in laws Fluke.

 

[RandyJ]

Re: 15 hp Force 1984 no fire.

Eurolarva... not that I'm some great electonics technician...but.. I am trying to get a little edumication here. I assume I do understand correctly that the primary is the little wires, one of which is the ground and the secondary consists of the big spark plug wire which knocks you on your butsky and ground is the other end of the secondary.

 

[eurolarva]

Re: 15 hp Force 1984 no fire.

I have been lucky enough that my 38 year old chrysler has never had ignition problems. I have several years as an electronic technician so what I am offering is theory not practical experience. A coil acts like a step up transformer. The magnets on the flywheel create a magnetic field that creates a small amount of electricity. This is induced into the secondary to shoot the voltage up to thousands of volts to create the spark. The primary or the wires going to the points or the flywheel should be around .6 Ohms. The secondary on the coil should be somewhere around 2Kohms or 2000 ohms. <br /><br />When using the ohm meter you should see a 1 or 0L to show that you have an open circuit. When you touch the leads together on a low ohm setting you will probably read about .2 to .5 ohms. What ever this reading is the primary coils should be slightly higher on ohms. You will probably read about 1 ohm on a good primary. If you secondary reads around an ohm chances are there is a short in the secondary. If the ohm reading is above 10 k chances are the wire in the secondary has burned open.<br /><br />It is best to test these when they are not connected to the motor however I dont know how hard this is to do. Iboats is a great site however ignition problems are tough to diagnose without expensive test equipment and a lot of times threads like this do not get answered. Good luck and I hope someone with more knowledge then me on this subject can help you.

 

[RandyJ]

Re: 15 hp Force 1984 no fire.

Thanks Eurolarva... everything checked out. I filed the points with emery cloth then broke down and bought two new condensers, cleaned the plugs and she cranked decently then replaced plugs & cleaned carb and she runs like a champ.... now if I can ONLY find a replacement recoil starter I'll be a very happy young man.