Points on an onan question

Trying to get the onan to run I picked up yesterday. I figured
out the wires. I have power to the points but no spark when I
break the points apart. If I hold the points open and jump
across with something I get good spark. But with the points
closed if I break them manually or bu turning the engine I get
nothing. I've filed them and they are clean and I can jump
from pad to pad to get the spark. It's just that with the points
closed and opened I get nothing. Yes they touch and yes they
break open. But I have to touch them with metal to get spark. I
am trying to get new but no auto parts store has them. I hope
to get new at John Deere tomorrow, but that doesn't help
today. Hate to loose a day. Any ideas?

When you manually jump the points how are you doing it??
Point to point or point to ground.
IE: check the ground of the points body.

Then take the wire off the points and check the wire post to ground with the points closed.

A common thing to do in USAF mechanic school was to put scotch tape under the points body or between the contacts.
It will drive you wild to you remember to follow the electric path to ground.

I've got two Onans Jon and that a new one for me,,try unhooking the condenser (temporarily) and see what you've got. Otherwise, Billy Shafer be be along and give us the answer.

Burnish the points by repeatedly drawing a clean strip of cardstock through them. When shined up, position crankshaft so points are "open" and clean off any debris with spray electrical contact cleaner and allow to air dry completely with the points still "open" before again checking for spark.

It's also POSSIBLE that there's no ground continuity from the "stationary point" through where it hinges from the mounting bracket, to the engine block.

Should be easy to check, ignition "on" points closed, with an unpowered test light, check for voltage at the movable point, the stationary point, and where it mounts to the block.

That will tell you where contact to ground is lost, for sure.

(BTW, I just checked online, and the DEERE dealer group I'm set up with doesn't stock them, order ONLY, hope you have better luck!)

All the points do is conduct coil current to ground when closed but interrupt it when open. Its easy to use a jumper wire to imitate what that does to see if it fires then, (with points out of circuit) connect a jumper wire to coils output touch it to ground to conduct current then separate to interrupt current (what points do) to see if it fires. ?????

Another easy test is put a 6/12 test light on the coils output, crank it over slowly, IFFFFFFFFFF points are good and working properly with no shorts etc the lamp should glow bright when points are open but go TOTAL OFF (noT dim) off when closed

If the points are burned pitted or even oxide coated the light wont go completely off when closed...

If the light never comes on when points are open, the points (or condensor) may be shorted... I have seen points springs assembly short out (Light never comes on) but if not clean and fully closed it never goes off as it should when closed

Insure the points open and close fully then try to clean/buff/polish them and check the gap. It can help to drag a dollar bill through them to remove oxide or use a points file if badly burned or pitted but replace if bad

ALSO the points assembly needs a good ground bond to the distributor and the distributor body needs well grounded. maybe try a jumper wire to insure the dist and points assembly are BOTH well grounded. Ground is needed to conduct coil current when points are closed (make light go total out)

Hope this helps

John T

That tells me the points are not conducting or actually closing, file them and test again.

Filed plenty and tested several times. That doesn't help. That's why I'm a bit confused. Don't really understand where the circuit is bad.

I just had this happen recently on my IH T-340 that had been sitting inside for some time. Same as you, tons of spark crossing points with screwdriver. Dragged flint paper through points and filed them still no spark cranking but plenty with touch of screwdriver. Finally I took them out and filed them good and shiny and smooth and made sure no grease. Put them in and zoom!

(quoted from post at 17:48:19 12/20/20) Filed plenty and tested several times. That doesn't help. That's why I'm a bit confused. Don't really understand where the circuit is bad.

Click to expand...

"Don't really understand where the circuit is bad."

Wouldn't take but a minute with a test light to see where continuity to ground is lost, either across the actual points or nearby parts,

Resolution yet?