Generator NEVER Just Starts

dxrobertson · 11-05-2021, 02:50 PM

This is a new Onan 4KY gas gen, about 10 hours on it.

The 1st problem was fuel related, could not get fuel flow. Turns out the fuel line out of the Ford tank had a kink in it. Fixed that a while back and have no further fuel flow problems.

Everytime I go to start this gen, which is every couple weeks; it turns over fine, but never fires. Pressing start.... 5 seconds.... 10 seconds... then I start to smell gas at some point; and know that the cylinder as well as spark plug are now flooded with fuel. Pull the plug, yes- soaking wet. Dry plug off, reinstall, and now the gen starts with no problem. This happens EVERYTIME I try to start this thing.

Once I get it running, run for a while, shut off, let sit a while; then it starts right up. Until the next session a couple weeks later.

I generally prime for about 10 seconds prior to 1st start attempt.

Is there some sort of magic procedure to get these gens to start from cold? Any suggestions?

wsherm · 11-05-2021, 03:48 PM

I usually have to prime mine for about 30 seconds if it has not been used in a while.

OnTheGo · 11-05-2021, 03:50 PM

If it starts/runs fine after reaching operating temperature but doesn't start cold, it could be the choke.

ARoamer · 11-05-2021, 03:52 PM

Quote:

Originally Posted by dxrobertson

This is a new Onan 4KY gas gen, about 10 hours on it.

The 1st problem was fuel related, could not get fuel flow. Turns out the fuel line out of the Ford tank had a kink in it. Fixed that a while back and have no further fuel flow problems.

Everytime I go to start this gen, which is every couple weeks; it turns over fine, but never fires. Pressing start.... 5 seconds.... 10 seconds... then I start to smell gas at some point; and know that the cylinder as well as spark plug are now flooded with fuel. Pull the plug, yes- soaking wet. Dry plug off, reinstall, and now the gen starts with no problem. This happens EVERYTIME I try to start this thing.

Once I get it running, run for a while, shut off, let sit a while; then it starts right up. Until the next session a couple weeks later.

I generally prime for about 10 seconds prior to 1st start attempt.

Is there some sort of magic procedure to get these gens to start from cold? Any suggestions?

Had a older Honda ATV. If you let it set for a week it would NEVER start without excessive cranking, similar symptoms you are having. Newer gasoline formulations and carburetor venting would cause the fuel in the carburetor to loose it's combustibility. If you cranked it enough it would eventually draw the old fuel out and fresh fuel in. If I drained the old fuel from the carb before starting it would fire right up every time.
Probably not practical to drain your carburetor, but if you can, try it. Maybe try some fuel stabilizer?

jyh818 · 11-05-2021, 04:23 PM

I was told that when you prime for 10 seconds, you hold down the "stop" and the red light will turn off. I hold for 10-15 seconds then switch to start. It could turn for some time before it fires up.

Docsouce · 11-05-2021, 04:30 PM

If my Onan 4ky hasn't been run for a week or more, the only way I can get it running is to remove the front cover, prime it for 30 seconds then manually operate the choke. Then it starts right up. I replace the cover and it is fine afterwards, until I don't use it for a week. Then it's back to the manual choke thing. . I had the dealer check it out and of course they said it worked perfectly for them. We went over the cold starting procedure again, and all was fine, until I hadn't run it for a week. Now I just pull the cover, choke it manually and be done with it.

dxrobertson · 11-05-2021, 05:07 PM

OK, good information so far.

Didnt realize this thing has a choke. Will 1st look into position of choke and possible manual manipulation, as flooded sounds choke related. Pretty funny, I may have to go back to my '68 Chevy C10 with manual choke days.

@ARoamer- that certainly sounds very similar to my problem. You are saying its the gas in the carb and related to VENTING? As opposed to the gas itself? I actually installed a fuel shutoff, I will try shutting that off and running the carb dry. Then try a start with proper priming.

Thanks to all, helpful and interesting info.

CAG · 11-05-2021, 05:34 PM

Quote:

I generally prime for about 10 seconds prior to 1st start attempt.

I think the manual calls for 30 seconds or more of priming and if my 4K has sat for a month or so it takes longer. The 55K would fire with about 10 seconds of priming.

Jagiven · 11-05-2021, 05:41 PM

You might also want to check the spark plug gap.

Newk · 11-05-2021, 06:06 PM

My 4k was a pain to start from day one. It would take several primes of 40 to 50 seconds if it sat more than a few days.

ARoamer · 11-05-2021, 06:44 PM

[Quote-@ARoamer- that certainly sounds very similar to my problem. You are saying its the gas in the carb and related to VENTING? As opposed to the gas itself? I actually installed a fuel shutoff, I will try shutting that off and running the carb dry. Then try a start with proper priming.-Quote]

I believe the carburetor venting allowed the gas to go stale, similar to letting it sit in a open container..
Good idea to run it dry, I always run small engines out of fuel if they have fuel shut offs. Please post if it helps!

Harvard · 11-05-2021, 08:30 PM

Quote:

Originally Posted by OnTheGo

If it starts/runs fine after reaching operating temperature but doesn't start cold, it could be the choke.

x2

Our thermal spring would always stick choke full open when hot and would not close when the thermal spring cooled down.

NYCANCamper · 11-06-2021, 08:26 AM

Quote:

Originally Posted by Newk

My 4k was a pain to start from day one. It would take several primes of 40 to 50 seconds if it sat more than a few days.

That describes my 2021 Onan 4k, exactly. When I exercise it monthly it takes multiple 30-60 seconds prime to start it. It will start but it's never been a one-prime process.

Stavman · 11-06-2021, 09:13 AM

As stated

Manual says prime for 30sec by pressing and hold the stop, bottom, on the toggle switch. Then press start
Usually I'll hold start after priming for about 5sec, release, do again. Usually starts in 2nd or 3rd try

Not priming can be hard on it...don't do that..lol

pconroy · 11-07-2021, 12:31 PM

Quote:

Originally Posted by NYCANCamper

That describes my 2021 Onan 4k, exactly. When I exercise it monthly it takes multiple 30-60 seconds prime to start it. It will start but it's never been a one-prime process.

wow - just for comparison's sake, my procedure is "prime for a ten count", crank for a eight count.

Usually takes three of those if its cold.
Four or five if it's bitter cold.

Florida Ranger · 11-07-2021, 07:13 PM

Just for information purposes Onan factory tech support told me concerning my 2018 4K generator. That after you shut it down 90% of the gas in the carburetor is designed to drain back to gas tank . This helps with keeping carb clean and not gumming up . That’s why when you start the generator up after sitting for a while you may have to prime it for a long time . Also the farther the Onan is from the gas tank the longer you will have to prime it .My 2008 4K never had to be primed even when it sat for 3-4 days, totally different with the 2018 4 K……

cherv · 11-10-2021, 01:41 PM

2019 class c. Start gen monthly, have never primed it, takes 2 to 3 times at 5 sec intervals to start. I never new to hold the stop switch to prime it. Never had to but good info,

drmike961 · 11-10-2021, 01:49 PM

Mine requires a minimum of 30 seconds prime then 5-10 seconds to start. Always runs great but needs plenty of prime.

thenne1713 · 11-11-2021, 06:07 PM

My OLD Emerald Plus (BGE/P) has no "prime" (that ONLY runs fuel pump) but has choke, and what works best for me is crank 3-seconds, pause 3 seconds, then crank; usually starts on 2nd crank; (sounds like) 10-second prime too long for yours?

dxrobertson · 11-12-2021, 04:27 PM

Quote:

Originally Posted by thenne1713

My OLD Emerald Plus (BGE/P) has no "prime" (that ONLY runs fuel pump) but has choke, and what works best for me is crank 3-seconds, pause 3 seconds, then crank; usually starts on 2nd crank; (sounds like) 10-second prime too long for yours?

I have tried it with various lengths of prime, including no prime, the result is always the same; the gen turns over and no firing at all. Then I smell gas, pull and clean plug, reinstall; then it immediately starts.

I agree, not sure why all this extended priming is necessary, unless the entire fuel line is void of fuel. Priming is to fill the carb bowl? I can tell by the sound of the pump when fuel is flowing at that point, have verified by pulling line at carb. This is generally a couple seconds of prime.

I shut my inline fuel valve closed and ran the carb dry a few days ago. Going to wait a week or so, then try a prime to fill carb bowl and start and see what happens.

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