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swebster 09-29-2005 01:23 PM

Generator Cutting Off
 
OK, here I am having a great time in Las Vegas BUT my generator has start acting up. Here is what has been happening:

Generator starts normally
Runs for a while
Power turns on.
After 1 minute (or one time 3 hours) it just cuts off.
I have to remove the ignition fuse and put it back in to start the generator again

Additionally,
Every now and then it backfires through the exhaust and dies

Pulled the plugs, and they look brown with some soot. Compression is 120 in both cylinders.

Fuel, Air, Oil filter and oil changed prior to departure.

It seems like it runs just fine then just decides to quit. Can't figure it out but an electrical issue seems to be my top choice right now.

We're heading back tonight and I would love to have AC for the ride home....any suggestions would be appreciated

smily 09-29-2005 01:40 PM

Try this
 
Oil level is high (or maybe even low). The generator is very sensitive as far as oil level goes.

The backfire is indication that oil is high. But the sudden cutoff is indication that oil is low.

I have been stumped by this before. it is imperative that oil level is almost dead on.

Generators "use" oil whether we admit it or not.

I have found that the generator works well while traveling down road. It seems that the oil moving around tends to "trick" the oil level sensor.

Janet H 09-29-2005 02:17 PM

Quote:

Originally Posted by swebster
OK, here I am having a great time in Las Vegas BUT my generator has start acting up. .....any suggestions would be appreciated

Glad you're having fun in Vegas. Have you put more chips in the thing? You have to pay to play.....:) :angel:

overlander63 10-06-2005 06:04 PM

Steven, does your generator have solid state ignition, or does it have points? If it has a solid state ignition, it sounds like your ignition module is about to take the big crappola. It will get hot, and short out. When it does so, it can cause misfiring and backfiring, as well as sluggish running. After it cools off, you can unplug the "run" fuse and it will start and run until it once again overheats.

swebster 10-08-2005 10:03 PM

Terry,
Thanks for the tip but mine is the "old school" points ignition. I adjusted the points, checked compression (120 in both), replaced the condensor, etc. I didn't need the genset on the way home as it was dropping to 45 at night in the desert so I just didn't think about why it wasn't running.

Once I got her back to Louisville I just parked her and wanted out for a few days. Tomorrow I hope to get over there and play with the generator and some other minor things that got annoying on this last trip.

I'm looking for a short or something in the control box at this point. Chaffed wires, etc. I'll also check the oil level as Ken suggested as it did run while underway and I just changed the oil before I left. I'll let you know what I find.

ALANSD 10-09-2005 08:16 AM

The only time I had an issue with cut off...it did it more going around a turn. It was oil level which was only a little too low.Never thought that would be the cause, but once remedied, it has not happened since.

Nye Thatcher 10-09-2005 02:28 PM

Back firing in the exhaust is usually unburned particles of gas igniting on red hot pieces of carbon in the exhaust system. It sounds like an ignition problem. Check out the ignition coil, and coil wire from coil tower to distrubuter on the early style ignition system. Hope this will help.
Nye

gunworks 10-24-2005 06:22 PM

Generator Cutting Off
 
Steven,

Don't know if this will help or not. My Onan developed a similar problem back in February. Would run for a while (5 minutes to over an hour) then shut down. Checked oil level, etc and everything was good. Seems moisture had fried the solid state controller board. Replaced at Cummins Midstate in Indy for $300.00 parts and labor with an oil change at same time. I think the board was around $180. No trouble since.

John

swebster 10-24-2005 07:12 PM

John,
Thanks for the tip. However, my genset is older and doesn't have a board. But, I do suspect something in the control box itself. A chaffed wire, etc.

noiva 10-24-2005 07:54 PM

Steven,

I just had similar problems with mine, and it turned out to be the spark plug wires. They were breaking down as the generator was running. A new set of "official" Onan wires did the trick. Obviously, if you've already tried that I'm not being any help. Another diagnostic trick that sometimes helps is to open the compartment door when it's dark outside. If wiring or ignition parts are failing they will sometimes visibly jump spark, but you can't see it in daylight. Hope you get it, regardless, and it's cheap to fix.

Noiva

Janets Husband 10-24-2005 08:15 PM

Quote:

Originally Posted by swebster
John,
Thanks for the tip. However, my genset is older and doesn't have a board. But, I do suspect something in the control box itself. A chaffed wire, etc.

That's a good start:
1.) Visual inspection, wires, points, fuel lines, filters, liquid levels...
2.) Determine if it is fuel related or electrical. (When it stops check the following)
a. is there fuel in the float bowl?
b. do you get spark when the set is turned over?
3.) If it is fuel; check fuel tank, fuel filter, fuel pump...
4.) If it is electrical; check battery, points, condenser, coil, plug wires...
Since you have points you will have to make sure the dwell is correct.
Check the spark by opening and closing the points manually. The spark should be BLUE and be able to jump 1/4"( place a screwdriver into plug wire at the plug end and hold it close to some metal and operate the points) . A orange spark indicates a bad condenser or coil or low battery voltage.
5.) If it appears to be fuel; check this by drizzling (small squeeze bottle up to 1/2 oz max.) a little fuel down the carburetor while cranking the set, if it kind of runs you know you will have to check the fuel system further.
Work your way back to the fuel tank from the carb. with a coke bottle checking for volume.
Hopefully this has given you an approach to trouble shooting your problem.

Good Luck. :bb:

swebster 10-24-2005 10:28 PM

Noiva,
Great suggestion and timely as I just solved a nagging hesitation on my other aircooled powerplant (my 71 Beetle) by checking it Saturday as it got darker and saw the faint blue sparks from the wires. I installed a new set the next morning and all was fine. I'll check the generator wires at night as well.

Gary,
Great list. The trouble seems to be intermittant which is frustrating. I started with a compression check and worked back up the ignition and fuel systems from there. Again, it will purr (sometimes for hours) then just die. Because of the backfiring I'm looking at under firing or missing and have suspected the control box for a while. A few other have had issues in there was well. Still a check of the fundamentals is probably a good idea as most of my diagnostic were performed in truck stops on the road.

I hope to resolve it this week so I'll report on any progress.

Janets Husband 10-24-2005 10:47 PM

Quote:

Originally Posted by swebster
Noiva,
Great suggestion and timely as I just solved a nagging hesitation on my other aircooled powerplant (my 71 Beetle) by checking it Saturday as it got darker and saw the faint blue sparks from the wires. I installed a new set the next morning and all was fine. I'll check the generator wires at night as well.

Gary,
Great list. The trouble seems to be intermittant which is frustrating. I started with a compression check and worked back up the ignition and fuel systems from there. Again, it will purr (sometimes for hours) then just die. Because of the backfiring I'm looking at under firing or missing and have suspected the control box for a while. A few other have had issues in there was well. Still a check of the fundamentals is probably a good idea as most of my diagnostic were performed in truck stops on the road. I hope to resolve it this week so I'll report on any progress.


When it stops try the fuel side first. I know these can be a bugger of a problem to find. One step at a time, I find when I jump around trying to troubleshoot I don't get very far. Work and eliminate one system at a time.

noiva 10-25-2005 07:07 AM

Steven,

I hope it's something simple like the wires (many times it is), but I have to say Gary has an outstanding list of diagnostic testing. Following his advice, assuming it's not the wires or ignition coil, you should get to the problem without replacing a bunch of things that aren't bad - like so many repair facilities do. I've followed the same steps Gary suggested for years, and he's done a great job of putting them in an easy-to-follow format. Frankly, as I'm sure you'll agree, it's usually something "simple".

Gary,

Great post of diagnostic steps. I should have followed through and done a similar list when I suggested the wires. Keep posting this type of thing. It's always helpful to go over things, even if one has done it for years. Thanks. I'll keep your list for the next time my generator acts up.

Tim

cooperhawk 10-26-2005 09:42 AM

Onan Generator
 
This may have no bearing but my generator would run for 15 minutes or so and then lose power, start to miss, and stop generatoring. Rpm's got too low. I put in a tune-up kit and it had no effect. I took it to an Onan trained mechanic and he tuned it up again. Ran great for 15 minutes and then the same thing. Had to warm up first. Finially took it back to him and said call me when it works. He called the next day. He found a screw on the back side of the carburator was loose and when it heated up and the hole expanded, it sucked air and caused the mixture to go lean. Tightened it up and now it works great again. The screw was in such a place that it could not be seen without a mirror.:blush:

swebster 10-27-2005 08:47 AM

Fixed it. Turned out to be four things:

1. The point gap was off (.025 instead of .015)
2. The plugs were fouled and their gap was off - replaced with new
3. The mixture was too rich
4. The 12V feed into the control box was chaffed and shorting (the real cause of the intermittant stalls.)

I also checked the plug wires for arching, etc. Everything else seemed to be fine. It's such a relief to go from backfirings, smoking, coughing to purring like a kitten with less than $5.00 invested.

Thanks to all that provided input.

ALANSD 10-27-2005 11:04 AM

way to go,my favorite type of repair....cheap and simple....

noiva 10-27-2005 07:17 PM

Generator cutting off
 
I never cease to be amazed at how simple things can cause so much trouble. Glad to got it fixed, and w/o even spending enough to buy 2 gallons of gas!

Tim


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