Onan no spark headaches

[FlyingDutchman]

The plate that holds the hydros on the machine is slotted, and was adjusted all the way down. A simple adjustment about halfway up and we are rolling with no belt slip and no hydro noise. Should increase fuel economy too I imagine. Lots of work piled up for the little guy to do, turning performance is there now too.

Took about 4 hours of scouring the manuals to find that out.

 

[LegDeLimber]

Take a look at the sheaves/pulleys and make sure the belt isn't riding on the bottom, between the "V" walls.
Just a bit of rust or corrosion chews away the belt width and eventually causes the belt to run on the bottom of the groove.
The sheaves will get too wide of a V in them too, over time from the metal loss.
So a new belt won't solve that problem and the slippage will just wear the sides off the new belt and keep the problem going.

Belts won't pull worth a darn when they hit the bottom of the groove.
You can load the tension to heck for a while but it's hard on bearings and any mounting points.
...think of cracked or broken flanges or tabs on pumps or alternators or spindles and the areas around where they bolt up.

 

[FlyingDutchman]

So far, it appears that the issue was that I didn't have the sheave/hydro plate adjusted right (my dad, who's had the machine apart extensively didn't even know about it), and moving that got all the tension I needed. Continued adjustment as the belt wears may be needed.

On the scale of things, this goofy little machine hasn't run long enough to wear out the sheaves, and these sheaves thankfully taper down to a point ins so I won't have the bottoming you are talking about, and it may even cut through the bonded part into two seperate belts eventually. You are right, a busload of tension will damage things. I think I have it a bit too tight right now, but anticipate it will wear in quickly to where it needs to be after the improper adjustment wear.

Excited to use the machine without the issues. So far just drove it out of the garage and into the shed haha.

 

[FlyingDutchman]

Machine ran successfully and completed the job. Needs to be rewired to charge the battery and kill without getting out and pulling the battery cable, but we have a job completed!

 

[FlyingDutchman]

So I'm having issues with the machine still.
Its running poorly and misfiring on one cylinder or just misfiring in general when under load. It can be brought back out of it by taking all load off of it and revving it up or choking/unchoking, (sometimes). That seems to indicate weak spark still. Seems to be getting worse.

Going to look at the points and wires, but obviously something going on that I'm missing.

 

[Sleepy]

I had to replace the coil on the Onan on my JD 318 because it would start running like s*it when it got up to temperature. I had that problem for a long time and it kept getting worse.
The new coil fixed it 100 %.

 

[FlyingDutchman]

Sleepy, where did you get your coil? I got a CKO (chinese knockoff) because an OEM one is several hundred dollars. Installed it last night. It performs exactly the same as my OEM maybe a bit worse.

Spooky Bermuda triangle stuff going on with the points and the ground before we got it to run. When the points close, it should ground out, collapse the field in the coil, and cause it to fire, but we were getting no ground through the signal wire (but ground on the points everywhere when they closed.... EXCEPT across the signal wire). We replaced the signal wire, but still no ground. I have no idea how its working at all, to be honest.

Hardwiring the battery (even though it has full 12v through the switch at the coil) is the only thing that made it a runner. I'm wondering if I need to run an auxiliary ground wire from the battery to the points or near the points instead of just an engine case ground near the mount.

I still have the 12v wire from the ignition switch hooked to the + terminal IN ADDITION to the direct battery connection. I wonder if there is a short to ground from that terminal that's causing the issue. I wonder if it runs better if I disconnect that terminal.

 

[Sleepy]

Sleepy, where did you get your coil? I got a CKO (chinese knockoff) because an OEM one is several hundred dollars. Installed it last night. It performs exactly the same as my OEM maybe a bit worse.

Spooky Bermuda triangle stuff going on with the points and the ground before we got it to run. When the points close, it should ground out, collapse the field in the coil, and cause it to fire, but we were getting no ground through the signal wire (but ground on the points everywhere when they closed.... EXCEPT across the signal wire). We replaced the signal wire, but still no ground. I have no idea how its working at all, to be honest.

Hardwiring the battery (even though it has full 12v through the switch at the coil) is the only thing that made it a runner. I'm wondering if I need to run an auxiliary ground wire from the battery to the points or near the points instead of just an engine case ground near the mount.

I still have the 12v wire from the ignition switch hooked to the + terminal IN ADDITION to the direct battery connection. I wonder if there is a short to ground from that terminal that's causing the issue. I wonder if it runs better if I disconnect that terminal.

It was probably five years ago and I don't remember where I got it but it wasn't anywhere near the price you mentioned. I used an inductive pickup timing light to find my problem. When the engine would start misfiring, so would the timing light.
I found a bad coil on a Kawasaki twin the same way.

 

[mrhemihead]

To determine if there is high resistance in any of the primary wiring...measure the voltage drop with a DVM. Measuring from the battery + terminal to the coil terminal, with the machine running, you should read zero volts. This is one case where zero volts is a good thing.
Don't be concerned about which color meter lead goes where. At most it should be just a few tenths of a volt.

Do the same with the - battery terminal to the frame, or wherever its attached. There should be zero volts from the - battery post to the distributor ground wire.

Be certain there is no side play in the distributor cam. This will cause the dwell to drift, it will run like crap if it does.

 

[FlyingDutchman]

A few things were going on, just spent all night on it. Didn't see your guy's replies till now.

Removed the questionable wire. No change.

The governor spring was in the way wrong hole, got a lot more rpm out of it the new way, which it needs plowing snow. Gained useable ground speed.

One of the spark plug wires was loose in the coil. Coincidence, it popped out a couple times while messing around. Tightened it up. Didn't help anything.

The main jet carb screw was about 4 turns out, oem is 1.5. I then backed the screw all the way out to clear the passage. Pretty sure it's missing a spring so it won't hold adjustment. Need to find a spring to use. Made a big difference with adjustment.

Lastly, the choke is an aggressive little cuss on this machine, and works great. However it likes to pull ever so slightly closed while operating which also causes a miss. The carb adjustment pulled me into this century with how it runs, a slap on the choke knob to make sure it's open all the way gets me no misfire with load...

Fingers crossed...

 

[FlyingDutchman]

Plowed with it early this morning successfully! Lots of choke slapping to make it behave though.

Now read that again with a dirty mind.