onan generator starts then immediately shuts down

My generator will start but immediately shuts down after start up. Then it blinks service engine(3 times). I have checked fuel and spark. Not sure what else to do? ANy help would be appreciated

Fill up your gas tank. Generators shut off around a quarter tank, so you really need a half tank or more of gasoline.

I keep my rig topped up before I set up camp so that if we have a power outage, or I have to make a run for it, there is plenty of gas for generator and or engine.

Also check the oil level.

Mine does the same.Model ky-k Oil level good, new premium fuel, cleaned the carb.Have swapped out the electronics with a good one. It will run well if I get it running by manually working the governor then it will run properly. When I start it wants to over rev then shut down. Played with the spring setting on the governor with no better results. Feels like the governor is late kicking in.

Couple of questions.  Is the engine stumbling then shutting down or does it act like it is being shutdown after starting?

Generally if carb issues it will load up, stumble or cough before shutting down.  If ignition and/or electrical it will generally shutdown immediately just like if you were to manually shut it off.

I have seen several lately that are having actual generator issues and not the powerplant that is the issue.  The powerplant does get feedback from the generator so if the generator is not producing power the exciter circuit is not energized which in many cases what controls the ignition circuit on the powerplant or ties back to the ignition module.

For verification, find the customer electrical connection and using a meter (carefully, this is AC current), connect the meter across the terminals, fire up the engine and see if it is producing 120VAC power.  If it is not then there is a problem with the generator not the powerplant.

It is beneficial to find out which part of the generator assembly is actually creating the problem before getting too deep as many times I find people end up chasing the wrong part of the system immediately thinking it is the powerplant and not the generator.

Also any time messing with a governor you should check/verify the frequency output as well as the voltage output.  RPM directly effects both.  When I set up a generator I check voltage then verify a final check using the frequency.

Mike

First. MOST Onans are kind of chatty. When they shut down (And there is a way to "Go back" and make 'em talk to you again) you can watch the light.. It will flash

Like ON ON ON-----ON ON ON ON  (That is 34)

Then you can look up the code.. THis may tell you what the problem is or it may be kind of cryptic

Post the code and we can go the next step

I recall one that flashed the code for "Low battery/Cranking speed too low"

What it meant is "I (the computer) Does not detect any 120vac so I'm shutting down.

That was a fellow forum member's at Quartzsite a decade ago give or take a  year. Thankfully they were parked next to a 30 amp outlet that works part time (not many of those in the desert) so they had power to charge their batteries every day.

Just tried it again. Sorry am working nightshift
Just woke up. I tried again and it is showing a 36 code. 3 then 6 flashes

This is what my manual shows for -ENGINE STOPPED FAULT?CODE NO. 36
(Engine stopped without command by controller)
Corrective Action:
1. Gasoline Models ? Check and fill the fuel tank, as necessary. (Note: The genset fuel pickup tube
is probably higher up in the fuel tank than the vehicle engine pickup.)

My code issue  15. If I get it running by cheating the governor manually it will run well after starting and give 123 volts with no load and 119 with load.

Sorry if I high jacked this thread but I thought we might have the same issues.

In my experience a Code 36 seems to be one of the most difficult to diagnose for the mere fact that when the Control Module sees something that it just doesn't understand or assign to a more specific  code, it seems to throw a Code 36 at it. ???

Even on my personal Onan 10kW QD a couple of years ago I ran into the same scenario.  The genset was shutting down just like I had turned the switch off, yet it kept throwing a Code 36.  I too did all of the preliminary checks "by the book", but in the end I decided to use my head and go to the source and check the generator output just for shits and giggles.  Sure enough, when testing right at the customer connection I had one leg putting out 120 VAC and the other leg 1.3 VAC.  Bingo, now that I know it is not powerplant (engine) related I could see the scenario.  The control module was not seeing the proper voltage on both legs so therefore removed the exciter voltage from the control module which therefore shut off the fuel solenoid.

Now when I work on a genset and don't have a more specific code to work with I go to the source and check the voltage output right at the generator and confirm or verify before going any further.  Many times it is the powerplant causing the shut-down, however, just as many times it is not and a problem with the generator portion of the genset but the code would have sent me on a wild goose chase.

If voltage output is at or near rated output then start looking towards the powerplant, otherwise look at things like the exciter circuit, whereas on diesel gensets supply the power to keep the fuel solenoid engaged and on gasoline gensets supplies power to the ignition circuit.  Other areas that may or may not be coded correctly are open or shorted stator windings or rotors (although rotors are quite rare).  Brushes and slip ring issues can also throw an erroneous code on occasion.

Bottom line is verify voltage output then go from there.

Hope that helps.

Mike