3020 john deere gasser. need help

[toolslut6.0]

I'm a diesel mechanic and I recently bought a 3020 john deere with a gas engine. It was priced right and ran but not very well. Anyway, I'm not very good with gas engines with distributors. I have power to the coil during cranking on both terminals. I thought that was weird so I replaced the coil. I have the same 12v reading on both sides of the coil. No spark with either coil on the coil wire to the distributor cap.

I just need a direction to go on. Thanks in advance for your help.

 

[toolslut6.0]

Bump

 

[gungatim]

do you have a schematic for a basic points/coil wiring?

like this one? http://www.schematic.pics/basic-motorcycle-wiring-diagram/17/ford-ignition-system-wiring-diagram/

- side of coil should ground with points closed, + side should be getting full 12v while cranking, and may or may not drop down to 6v (through ballast resistor) when in run.

 

[gungatim]

trace the - side to the distributor if you can, pop the dist. cap and see what's going on.

you can run 12 v to + side of coil and ground- side quickly unground and get a spark. I do this alot to see if a coil works before going on to points, ign. switch, etc.

 

[jjkrjh]

Like was said in previous post, you aren't getting the triggering(ground/negative) from your points. Point gap .021

 

[toolslut6.0]

Like was said in previous post, you aren't getting the triggering(ground/negative) from your points. Point gap .021

Thanks guys I'll check it out tomorrow when I get off work and go to the shop.

 

[tdkkart]

Look at it this way.
Power goes in the + terminal on the coil, goes inside, goes roundy-round inside the coil about a bazillion times, comes out the - side where it's connected to ground through a switch(points). When the points are closed, current is flowing and everything is happy, electrons flowing like crazy.
Now, open the switch(points) and the electrons get pissed cuz now they have nowhere to go, so they JUMP out the top of the coil.

So, if the points are opening and closing it should make sparks. If it's not making sparks something isn't working, and assuming the wiring is all there, it's usually the points.

Ultra simple explanation, but it pretty much works that way.

 

[LG63]

Just for reference, the voltage on distributor side of coil should be zero or near zero when points are closed. When points are open voltage will measure the same on both sides of coil. Therefore a test light connected to distributor side of coil should flash off and on during cranking.

 

[gungatim]

THis is why I keep around old shop manuals from 50's-70's, timing lights, etc. You forget all the details of a points ignition system when all you work on is newer stuff, but there is still a lot of small engines, bikes, cars, tractors, etc. still out there where you need to know the old school basics.

 

[RPH]

New stuff, old stuff same principle. Only thing changed is the type of switch.