Generator priming

[The Rookie]

2017 Windsport 29M w/Onan 4k genny.

Did my monthly generator run this morning. The temps were about 45. It seems to take quite a long run on the priming. I first attempted it with the generator switch on the panel located in the cabinet above the door. I tried it 3 times. I held it down to prime until the red light came on then held it down approximately another 5-7 seconds. It did not start, it turns over just fine. I then moved to the start switch on the generator. Executed the same steps. It took about 3-4 times before it started. My fuel tank is nearly about 99% full.

Should I prime for an extended amount of time and attempt fewer starts? I feel the repetitive starting attempts can’t be good.

 

[Chateau_Nomad]

I hold the prime on mine down about 30 seconds on a cold start. I think the gasoline gradually drains back to the tank after sitting idle. I'd rather prime longer and hammer the starter less. After about 30 seconds prime it has always fired up almost immediately.

Through experimenting find how long yours takes to prime for easy starting. Then stick to that.

 

[The Rookie]

I hold the prime on mine down about 30 seconds on a cold start. I think the gasoline gradually drains back to the tank after sitting idle. I'd rather prime longer and hammer the starter less. After about 30 seconds prime it has always fired up almost immediately.

Through experimenting find how long yours takes to prime for easy starting. Then stick to that.

Ok, that makes sense. Thank you.

 

[DavidEM]

Yes, hold the primer button down longer when it has set for a while. Much better than cranking longer.

David

 

[16ACE27]

I believe the manual says to prime for 30 seconds when cold.

 

[Chateau_Nomad]

I believe my prime pump actually stops (the red indicator light goes off) after 30 seconds or so. Try yours and see if it automatically shuts off after a pre-programmed time.

 

[The Rookie]

Thanks for the replies. Next available time, I will test the 30 seconds of priming.

 

[16ACE27]

I believe my prime pump actually stops (the red indicator light goes off) after 30 seconds or so. Try yours and see if it automatically shuts off after a pre-programmed time.

I'll have to try that. I usually stop at about 20 seconds.

 

[dkoldman]

For kicks I just started mine, 80% of the time it starts on its own by AGS, but since it is cold and batteries are fully charged; I had to start manually with START button.

I pressed the Start button (no priming) and it it started in about 6 seconds. That is about 3 seconds longer than normal if I am manually cranking. I never use the Primer button, short the 1st year when it was brand new and I was learning about how the Primer button works. I know it has Primer button for reason, but for some reason, I never need. It has been about 6 weeks since it was last used?

In an hour I will shut down.

 

[Chateau_Nomad]

dk... for giggles hold your prime button in and see how long before it shuts off. 30 seconds or so? Curious what WBGO uses. Won't hurt anything... just start it and use the gas.

I'm going out to fire mine up shortly.Will test prime again.

 

[dkoldman]

dk... for giggles hold your prime button in and see how long before it shuts off. 30 seconds or so? Curious what WBGO uses. Won't hurt anything... just start it and use the gas.

I'm going out to fire mine up shortly.Will test prime again.

Roger that Chateau. I will shut her down and wait a tad.

FWIW, I actually have two Primer Buttons. One on the OEM panel with ON/OFF and Hour meter that I never use, and the more modern Onan EC-30 Pad I had the WBGO Dealer install, it controls the auto start / off functions. I believe years ago in discussing this with ACE, he reasoned that my AGS when auto starting was smart enough to Auto Prime itself. But thus far when I manual start with the START button(s) it has never not started or took any length of time to raise a question. I later concluded that generally speaking, I use my generator with much greater frequency than most? Maybe not allow it to run as long as most, but have more Start up based on the AGS starting / stopping for me. I believe it is why Onan extended my Genny's warranty to 3 years when I had proof that the Onan EC-30 had been installed by an Authorized Dealer.

 

[Chateau_Nomad]

Well... I was wrong about the "automatic" prime shutoff. I held the button in, and after just over a MINUTE I could still hear the pump running... so I released it.

It slightly flooded... took about 15 seconds of cranking to start.

Regardless, the 30 seconds on mine seems to be the magic number. Obviously it varies from unit to unit. Again, just try different lengths of priming (or NO priming) and see what works for you!

 

[dkoldman]

Well... I was wrong about the "automatic" prime shutoff. I held the button in, and after just over a MINUTE I could still hear the pump running... so I released it.

It slightly flooded... took about 15 seconds of cranking to start.

Regardless, the 30 seconds on mine seems to be the magic number. Obviously it varies from unit to unit. Again, just try different lengths of priming (or NO priming) and see what works for you!

Ok, thanks for the update so I did not try Priming as no need for me to NOT leave well enough alone.

But here is more info that may or may not mean something in your research.

It turns out the only true Primer button I have is on the EC-30 AGS.


OEM WBGO Setup

The OEM pad by WBGO does not even mention Primer. The OEM has one button/switch Press Left to to START and press Right side to STOP

It has note underneath that says Hold START until engine Starts.

I have in my handwritten notes from years ago in talking with ONAN that pressing / holding the STOP button will prime. But I am sure I have never done this in 5 years.

The below is in my RV's Owners Manual but it came from Onan, not WBGO
​

PRIME THE FUEL SYSTEM ( as necessary)
If the generator set has run out of fuel (gasoline and diesel models only), Prime the fuel system. Hold the STOP/PRIME for at least 30 seconds for gas generator sets or at least 1 minute for diesel generator sets. The Status indicator light will stay on solid white while the pump is on.


Onan EC30 AGS Install

In addition to the above. I have a STOP / PRIME button on the EC-30 Pad. I have done this 4 - 5 years ago. I don't recall a white light but it is a red led that lights up when it is starting.​

I hope this helps. My takeaway is that they are saying unless one runs out of gas, they should never have to prime, but they cover themselves by saying as necessary.

 

[Chateau_Nomad]

Final takeaway for the O.P. Sounds like you simply need to hold the primer button down a little longer. Just keep adding a little more prime each time until you find the sweet spot.

 

[16ACE27]

Ok, thanks for the update so I did not try Priming as no need for me to NOT leave well enough alone.

But here is more info that may or may not mean something in your research.

It turns out the only true Primer button I have is on the EC-30 AGS.


OEM WBGO Setup

The OEM pad by WBGO does not even mention Primer. The OEM has one button/switch Press Left to to START and press Right side to STOP

It has note underneath that says Hold START until engine Starts.

I have in my handwritten notes from years ago in talking with ONAN that pressing / holding the STOP button will prime. But I am sure I have never done this in 5 years.

The below is in my RV's Owners Manual but it came from Onan, not WBGO
​

PRIME THE FUEL SYSTEM ( as necessary)
If the generator set has run out of fuel (gasoline and diesel models only), Prime the fuel system. Hold the STOP/PRIME for at least 30 seconds for gas generator sets or at least 1 minute for diesel generator sets. The Status indicator light will stay on solid white while the pump is on.


Onan EC30 AGS Install

In addition to the above. I have a STOP / PRIME button on the EC-30 Pad. I have done this 4 - 5 years ago. I don't recall a white light but it is a red led that lights up when it is starting.​

I hope this helps. My takeaway is that they are saying unless one runs out of gas, they should never have to prime, but they cover themselves by saying as necessary.

FYI the Thor panels do not mention "Prime" either, but it is the Onan remote harnesses that are routed to the remote switches and the switches operate per the Onan manual for remote switches.

 

[The Rookie]

Final takeaway for the O.P. Sounds like you simply need to hold the primer button down a little longer. Just keep adding a little more prime each time until you find the sweet spot.

I will test the time the next chance I get.

Thanks again

 

[OldWEB]

Has been discussed a few times before, here is one...
https://www.thorforums.com/forums/f4/onan-4ky-generator-hard-start-36643.html

Priming only fills the carburetor bowl, once full the float is s'pose to stop any more coming in, so lengthy runs of the pump is unnecessary.
I installed a shut-off valve before the carb and so now I remove the fuel line to the carb and pump some gas into a container... this tests the fuel pump, I time how long to get fuel to that point and it draws up fresh fuel to the carb. Re-connect and then prime the carb.
In the link above, I still have the issue with the choke not closing after a run and I have to manually close it. Now it always starts.

My 2¢

 

[Redsand]

On my Onan 4000 (20 years old now with under 200 hours) 30 seconds of priming always works for me. I also added a fuel shut off and run it dry before storing to prevent clogged carb issues. Best mod I've done to keep the carb happy.

 

[DavidEM]

I just started my Onan 4000 after being laid up for two months. I primed it for 30+ seconds and cranked for 6-8 seconds but it didn’t start. Then I primed it again and it finally started after 3-4 seconds of cranking.

Who knows why it takes so long, but after doing this for four years, it has always finally started.

David

 

[Chateau_Nomad]

I just started my Onan 4000 after being laid up for two months. I primed it for 30+ seconds and cranked for 6-8 seconds but it didn’t start. Then I primed it again and it finally started after 3-4 seconds of cranking.

Who knows why it takes so long, but after doing this for four years, it has always finally started.

David

Similar routine here. I attribute the long priming time to the distance gasoline must travel from the gas tank to generator carb. I think over time the gasoline slowly drains out of the fuel line back into the tank, and you have to pump it back up to the generator.