No sparks on 115hp

[rupertmja]

My 1970 115hp Johnson has no sparks. No power seems to come out of the single coil on the top of the motor that feeds the distributor under the flywheel. (I connected a strobe to the coil to see if there were any pulses). However, the coil registeres 3 ohms on the supply side and 250 ohms on the output side. Is this normal and if so, does that suggest that the powerpack is at fault? Just need clarification before I start hunting for what I think will be an expensive item.

 

[bigpoppakdog]

Re: No sparks on 115hp

I went through a scenario this summer with my 1970 115 motor. Can you explain a little more about your motor? Did it start before etc... my problem ended up being a "clipper" switch that was bypassed with a 2 inch wire by jumping from terminal 7 to 9. Ended up being a faulty wire that would cut out all power going to the pack, therefore no spark going to the plugs. Wire would wiggle now and then and the problem would disappear. Ended up changing power pack rectifier, coil, sensor and stator. Expensive lesson. I have two extra packs now.

 

[rupertmja]

Re: No sparks on 115hp

Thanks for that. I got this motor partly dismantled. Obviously, it had had a problem and someone had been pulling it apart to find it. Well. I pulled a bit further and found a totally knackered water pump so my guess is that was the cause of whatever grief he was having. Anyway, it is mostly back together and has no spark. I spent hours going thru the wiring then found that the fuse had blown - doh. But to no avail. Then, I sussed the safety switch behind the throttle lever - got to get that position correct for power. Took the flywheel off and checked the sensor gap - OK. Can't really see much else in there. Checked the external coil and it has 12v going in - blue wire but nothing coming out - but resistance wise it seems OK. It is my main suspect at present, and cheaper to try than a powerpack. What do you think?
PS Mechanically, two pistons have been oversized so it has been apart before and worked on. Better still, there is almost no corrosion at all either inside the water pathways, or externally. Not bad for 1970 - doubt a Japper would last as long.

 

[tashasdaddy]

Re: No sparks on 115hp

look here several pages of test. http://www.boatpartstore.com/page28.asp

 

[bigpoppakdog]

Re: No sparks on 115hp

you can't check the blue wire accurately unless you use a dva meter. Are you sure its wired correctly at the terminal? Is that worthless clipper switch still attached to this motor? If you check with a regular meter the purple power wires for voltage that will at least tell you that your key switch is ok and you have power going back to the motor. From there the pack needs to be checked with a dva meter. Can you post a pict. of the back of the motor specifically the terminal block?