Correct way to start Onan 4K generator

Try a fuel filter with a check valve

My current one and my previous one were the same way. It take an ungodly long time to prime them. And it seems no matter how long I prime, it still won't fire up without a few tries at cranking.

I have suspected the choke is set too lean but have not gotten around to looking at it. I downloaded the service manual and will eventually check the choke adjustment.

If not the choke, then it's a poor design in some way. Maybe emissions tuning has created this problem. Again though, the choke should take care of that.

My previous Onan 4k Emerald 2 (1996) did not have a prime function. Check your manual. As far as cranking, 30+ seconds is too long for routine starting. If it starts using your second pattern (10 / 10) go with that, or better yet, try breaking it up in 5 second cranks like Bobbo above does.

I prime mine for 60 seconds, timed with my watch, by holding the STOP button before I ever try to crank it. I can hear the fuel pump so I know it is priming. Then, I crank for 5 seconds on, 5 seconds off. It takes 4 or 5 repetitions of this before it starts. More in colder weather.

thanks all for your replies

I have a 94 onan with no prime function.
on a cold start: I press Start 15 seconds off
Start for 15 seconds off.
and some times if it's cold a third time.

And it is only to prime, because as old as it is I might have a small air leak back to the tank.

That way I do not heat up the starter.

Bob

Many, perhaps all, of these generators are supposed to have a prime function by holding down the stop side of the switch prior to cranking (you should hear the fuel pump running if it's priming). If it's only an initial cold start that takes a lot of cranking, try doing this for 30 seconds or a minute before cranking.

On my Onan 4K generator, this prime function is either non-existent or broken. I should investigate that in my copious free time.

you should not crank it that long, that seems like a tuning issue. You will eventually overheat the starter and end up replacing it. Better to do multiple shorter cranks with a few seconds in between



Chris