Generator and priming

[model71]

Hi folks,I have a 2251SLE, 2015.Forest River Motor home I have been having a hard time starting the generator once a month during the winter season.The machine was new to us last summer, the generator which is an onan 4000, was used very little.Oil is good plug is good, twenty hours on generator. Could the hard starting be caused by priming too little or too much,not sure how long to hold primer rocker switch down.During winter months I have never started or tried to start below the freezing mark,but close to that.look forward to your thoughts. Thanks

[BBQGUY]

Priming the generator is to fill the carburetor bowl and to build up fuel pressure to keep the fuel bowl full. Onan recommends to prime for 30 seconds if you ran out of fuel. You usually don't have to prime before starting as there is fuel in the bowl, but it doesn't hurt to prime for 15 seconds or if you can hear the fuel pump run when priming, stop when the pump stops.
If you didn't add a fuel stabilizer to the tank before storing the RV, then the hard start issue could be fuel. Fuel containing Ethanol is not kind to small engine carburetors. Onan hasn't sold a carburetor rebuilt kit in over 10 years for the RV line of generators. It is now strictly a replacement part.






.

[SeaDog]

You might try putting some SeaFoam in the fuel and then starting the generator and run it loaded (elect heater, fans) for 2 or 3 hours and clean the system up. My old Class A was doing that and after the SeaFoam treatment no more problems it was an Emerald 5000 Onan

[bpadamson]

If I remember accurately, mine calls for a 30 sec prime to get it started (I read it in the manual or on line). In the winter it takes a full 30+ to get it going. It may make a difference where the fuel tank is located. Our gen is up front and fuel tank in in the rear...

[sgtlm17]

YouTube has two videos on cleaning up the carb on a generator. As stated the fuel nowadays is an enemy of the Onan carbs. You really need to run them under load every 3 to 4 weeks. One video is from Seafoam the other is how it's done on the Onan 4000 which I just did recently. Very simple process.
PS prime till the red light comes on
https://youtu.be/355iwj83LqI

[GL1800Rider]

Mine has always been difficult to start. I usually prime about 20 seconds, crank for a few seconds, prime again and then it usually starts on the second try but always the 3rd. I exercise it at least once a month under a load. It's been that way since new and now has about 96 hours on the clock.

[model71]

Yes I did fill the gas tank in November when I put motor home away,Stabilizer and sea foam were put in gas tank, engine and generator were run at that time to get sea foam to carb.I do run engine and generator two hours each month with a load on generator.I have not heard the fuel pump run while priming.The red light comes on when I hold the primer switch in under ten seconds. Genny starts after repeating the priming process two or three or four times,Primer depressed from ten to twenty seconds. when it fires up,its quick and clean, no stumble.Maybe i need a longer hold down. what do you guys do?

[brucemc]

That's similar to mine as well - Prime 15-20 seconds, crank. If no fire in first 2-3 seconds, back to prime. It can take 3 or 4 cycles before it fires to life. Once in a while I'll hold the crank a little longer, but 5 seconds is about it. No fire, no use in wearing out the starter/flywheel.
I do hear the pump while priming, but it is pretty quiet.

The same generator in the Four Winds was a bit easier to start, but still took the same process. It had a louder pump - it was easier to hear. Of course, I had to replace that pump a few years ago.
The Four Winds has 115hours, where the Sunseeker has 15 hours. Most of that 15 hours is a monthly run.

[model71]

So the consensus seems to be 15 to 30 seconds for priming.I was concerned about possible flooding the genny.If I prime till light goes on,approx five seconds,doesn,t seem to like that, Im leaning towards the 15 to 30 second idea. Any other thoughts?

[brucemc]

Actually, the prime doesn't start until the light comes on. It's a time-delay feature, as that's also the stop position. 1 rocker switch, 3 functions!
I feel that the pump will fill the bowl until the float closes off the jets, then it quiets down. I listen for the pump, and when it gets a little quieter at 15-20 seconds, I try cranking it.

Seems to me, after this many years and the cost of Onan generators that it would have a lot better fuel system. And, this day in age, they should be an inverter style instead of the decades old fixed RPM to maintain the frequency.

[Jmkjr72]

Originally Posted by model71

Yes I did fill the gas tank in November when I put motor home away,Stabilizer and sea foam were put in gas tank, engine and generator were run at that time to get sea foam to carb.I do run engine and generator two hours each month with a load on generator.I have not heard the fuel pump run while priming.The red light comes on when I hold the primer switch in under ten seconds. Genny starts after repeating the priming process two or three or four times,Primer depressed from ten to twenty seconds. when it fires up,its quick and clean, no stumble.Maybe i need a longer hold down. what do you guys do?

Seaford alone is enough it stabilizes the fuel
Having ran my own small eninge shop I am not a fan of stabil I saw more gummed up carbs with stabil then without if they filled with e10
Never saw any issues with my customers that just used seafoam

[model71]

Thanks Brucemc, I did not know that the priming started when the light came on in the rocker switch.once the light is on I should be holding for another 15 to 30 seconds. I will try to hear the fuel pump.when pump stops then start the generator?
Thanks for the tip on the stabilizer, I,ll stick to sea foam.

[brucemc]

Originally Posted by model71

Thanks Brucemc, I did not know that the priming started when the light came on in the rocker switch.once the light is on I should be holding for another 15 to 30 seconds. I will try to hear the fuel pump.when pump stops then start the generator?
Thanks for the tip on the stabilizer, I,ll stick to sea foam.

I don't believe it ever stops, but it gets a bit quieter. Independent of the sound, I usually count to 15 after the light comes on then try the crank.

I've always had success using this process, except the time the pump quit in the older unit. I knew there was an issue because the pump was silent during the priming process.

[model71]

Thanks to all, I'm going out the door to try right now.I appreciate the advice.

[Kirk S]

I appreciate the information gained from these posts. I start my Onan 4000 using the Lippert tablet and it starts quickly every time. With all the talk about priming, etc. I'm wondering if the generator genie is doing all of that before starting as it takes about 15 to 20 seconds after I press start on the tablet for cranking to begin.
I have a side question about Seafoam. Is it okay to use in a new engine. The generator has les than 2 hours and the Ford V10 has about 2600 miles. Thanks.

[Hoglou]

Our seems to start much quicker when the coach motor is running, maybe a prime assist effect.

[bubbles]

From the ONAN owners manual:
"Position the control switch to STOP/PRIME for 30 seconds. The status indicator stays on while the pump is on"

[Iwannacamp]

I used to sell Seafoam(app 20 years) and truly believe in this product. I would not use in crankcase unless you are having trouble...i.e. The Ram with the sludgy lifters. You can use anytime you want for preservation and 2-cycle engines, but it doesn't remove carbon if there is none. It is supposed to stabilize fuel for 2 years.

https://seafoamsales.com/

[model71]

Thanks Bubbles, now we have the directions straight from Onan.30 seconds it is.What a great forum,and nice polite crowd.