Onan RS1200 Won't Run

My guess would be no spark or no fuel. Have you physically checked for a spark? Is the propane solenoid opening? These would be two good places to start checking.

What changed since the gen set ran correctly?

Do you have a test light of the same voltage as the starter motor of the gen?

With the engine in the run position, check for voltage on the positive side of the coil. If you do not have voltage, check for voltage there while you try to crank over the engine. If not, you need to follow the voltage from the battery until you find out where it stops.

If you do have voltage at the positive of the coil, next go to the negative side. Crank the engine over and see if the test light goes on and off as the engine turns over.

Next step is to open the distributer cap. If you had flashing light, pull the coil wire out of the distributer cap, and check for spark while cranking. If no spark, or a weak yellow spark, it is coil, or coil wire.

If you had power at the positive of the coil, but not flashing on the negative, examine the points. Are they opening and closing as the engine turns? Is there any corrosion built up on the points? If so file clean, and recheck from start.

Look for signs of cracks in the distributor cap, and rotor. High voltage will find it's way through the center of the rotor if it can. Look for signs of electric arcing.

Enough for now. Check, and get back to me.

If you ran it lean (ran out of propane while it was running) you may have burnt the valves.

Put ht lead (the one that goes to the spark plug) onto a spark plug place spark plug on metal part of genset so you can see it and crank, Is there a Spark ?

if spark is ok.

replace ht lead bak on spark plug on gen set.

remove air filter and spray carburettor cleaner or some othe flammable spray into air intake while cranking, Does it start.

1 If it starts while your spraying its fuel related

2 if it doesnt start its Igntion ie low spark.

If fuel related propane can foul the regulator with a tar like substance after a lot of running and needs to be cleaned out.

hope this helps

report back with findings

Silly thought but you also need to verify that the gas shutoff valve hasn't been closed or the gas line kinked. You also need to verify that some mud dauber wasp hasn't set up a wasp nursery in your carb intake. You may need to verify that the fuel orifice in the carb. hasn't been plugged up with dirt or rust scale that might have been in the fuel line from the tank.

Also, you need to verify that the oil level switch isn't stuck or shorted to ground. if the system does not believe that there is oil in the system, it will disconnect power to the coil.

Rorschach: has hit the nail on the foot, I recall some years ago that an oil switch was fitted to some engines stop the engine runing.

worth a try

I'm a little confused about your description. First you state it doesn't catch, I presume you mean it will not run on its own. Then you state it sounds like the starter is still running in the background. Does this mean the engine is trying to run but the starter will not disengage. Please clarify if you will, thank you.

I have a 16hp onan engine on a Miller welder that only fires and runs on one cylinder. Can the coil cause this problem? Do I need to look further?

How many cylinders does it have? Does the unit use one coil to supply spark to all the cylinders? If it has only one coil the unit could have a hung up valve. Did you check the other plugs, wires etc.? Need more information. Did it run ok the last time you ran it?

h

I takes 3 things to make any engine run... period: Fuel, Fire, and compression. That's it! Find the one missing and you have your problem solved. You can call me if you like 713 448 0703.... Dudley. This is what I do, fix small engines.

I would like to add that oxygen is also highly favored as a component of combustion. It may seem obvious, until the air filter is plugged, painted,or shut off.