Generac generator (natural gas) starts but won't stay running

It will only run for about 8sec's then stops. It does it 4 or 5 times then shuts down.

Reply to
TOM
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Maybe it is sensing low oil pressure and shutting down?

Reply to
Jack Goff

n shuts down. -- posted from

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Are you sure the gas supply can keep up with the needs of the generator? H ow old is the unit, when did it last run satisfactorily, etc, etc.

Reply to
hrhofmann

I had to replace a lot of defective oil pressure sensors on Generac gensets for that reason. I had forgotten until you brought it up. I tested for that by disconnecting the terminal from the post on the oil pressure switch and making sure there was sufficient oil in the crankcase started the generator. If the engine ran with the oil pressure switch disconnected then stopped when the wire was shorted to ground, that indicated a problem. The switch shorted the connection to ground when oil pressure was lost. There is a time delay allowing oil pressure to build up and open the connection when proper oil pressure is reached. With the engine running, use an ohmmeter set to the lowest scale, the switch should test open with the engine running. I found that the big old oil pressure switches meant for older automobile oil pressure lights worked better than the OEM replacement available from Generac which was a cheap dinky little switch and it was a very common failure point on their gensets. ^_^

TDD

Reply to
The Daring Dufas

Check the low oil shutdown switch (and the oil level)

Reply to
clare

Could be something simple like that. Or it could be more serious. I went through diagnosing one last year that also started up, ran for some number of seconds, maybe 10 - 15 secs or so, then shut off. As I recall, a few things happen around that time. One is that upon starting, the ignition voltage is supplied by the battery, but then after starting, it switches to being supplied by one generator winding that serves that purpose. If that winding or associated circuit is bad, it loses ignition. Also, as I recall, the generator control looks for normal voltage after start-up. If it doesn't see it, then it will shut it down.

In the generator I had, it was a bad rotor for sure, and possibly a bad stator too. I took a look at all the complaints on Amazon about similar Generacs and concluded it wasn't worth fixing. That had also been the conclusion of the service guy who diagnosed it for the neighbor I got it from. Being that it was only about 5 years old, I thought I might get lucky and be able to fix it, but it didn't pan out.

I found the Generac service manual online which had good detail on the various test procedures.

Reply to
trader4

Also, the unit here had a couple of fuses that were accessible right at the control panel. Checking them is quick and easy. As another simple test, if you're comfortable working with AC, put a test meter on the generator output. If you have 240V during the time it's running, then you know the generator section is working. If not, then you know you have bigger problems.

Reply to
trader4

replying to The Daring Dufas, Dave wrote: Oil light stays on and it keeps shutting down

Reply to
Dave

And you're a dangerous idiot.  Somebody shows up here, basically says my furnace starts and only runs for a few seconds, shows no indication of having *any* technical knowledge of dealing with an oil burner and you tell him to keep pushing the reset button and take a screwdriver, put it across a high voltage transformer.

Good grief.

Reply to
Cyndi Jacobs

replying to Cyndi Jacobs, trader 0 wrote: What oil burner?? subject is; Generac generator (natural gas) starts but won't stay running

Reply to
trader 0

Connect a voltmeter to the AC output and see if you see 240V when it's briefly running. The controller looks for that and if the generator isn't generating, it shuts it down after it runs briefly, maybe 15 or

30 secs. In other words, your problem could be in the generator, not the engine.
Reply to
trader_4

Dave-

Before the generator's engine starts, there is no oil pressure. The oil sensor is ignored until the engine has a chance to come up to speed. If it then shuts down, it normally indicates a low oil level.

If you are sure there is enough oil, disconnect the wire to the oil sensor and see if the engine keeps running. You could have a bad oil sensor.

Fred

Reply to
Fred McKenzie

As I discovered on my Generac propane powered generator, rusting internally caused a leak between the exhaust chamber and the other air chambers. After I plugged the leaks by mounting a cover plate, the generator started and continued running. Apparently the exhaust was starving the motor for oxygen.

Reply to
lhines2

If you choke out the throttle body it will run

Reply to
dannyjones419

yes it ran after I choke it out.

Reply to
Michael Hovey

Yes I choked it out and it ran fine

Reply to
Mike H.

On Thu, 4 Feb 2021 14:45:03 +0000, Mike H. posted for all of us to digest...

From my crystal ball it sounds to me like a vacuum leak around the carb. Look on U Tube for help on this because I think Generacs are a popular topic.

Reply to
Tekkie©

More likely a problem with the demand regulator - particularly if you did any screwing around with it

Reply to
Clare Snyder

No screwing around with it, found a lot of rusted metal in cavity where it is . Thought some rust got in plenum or regulator.

Reply to
Mike H

No carb, but it does have airbox and no openings i can see

Reply to
Mike H

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