Gas check valve for Genset

[Gjac]

I notice that whenever the genset sits for a while it takes me usually 3 tries before it starts. I think what happens is the gas flows from the carb back into the tank. I was thinking a one way valve would prevent this and make it easier to start. Has anyone added a check valve for a genset fuel line to fix this problem. Maybe the newer ones already have one. This is a 21 year old Kohlar 5CKM21.

[wa8yxm]

Well I guess I'd better explain then why adding a check valve won't help.

There are two check valves in the line already, Fuel pump inlet and outlet, if they are not working then the fuel pump can not pump fuel and it will NEVER start

Adding a 3rd,, Thus won't help.

(The reason I did not explain this before is I had a much longer and far more techinical explanation of what the problem is in mind.. (The Carbrator fuel evaporates, lenthy explanation of why) but re-reading the fact above hit me much simpler.

[enblethen]

I did find some listings last night.
I did see solenoid listed in some places. It is mounted near the carb inlet. It didn't look like what some have. It could be for LPG model.

[Gjac]

enblethen wrote:
I tried to look up your model and didn't find it. Any other numbers before the "5"?

No Bud, that is the correct model number. I had a difficult time also finding a service manual for it on line.

[4x4van]

Not sure when the Onan prime feature became available; my '88 did not have it, my '04 does have it. However, I initially thought my 04 primer didn't work; realized that you have to hold the stop button for about 4-5 seconds before it kicks into the prime function. On my '88, I added a manual switch to energize the fuel pump and prime it when needed (after sitting; first start of the trip).

[enblethen]

I tried to look up your model and didn't find it. Any other numbers before the "5"?

[Gjac]

Gjac wrote:

enblethen wrote:
I would think the fuel pump on your genset would block fuel from draining back to the tank.

I don't know how that works, if I use it every few days it starts right up on the first try after it sits several weeks it always take 3 crank cycles to get it started. I have a spare fuel pump so I can check that tomorrow.

The fuel pump allows air in each way so I would not assume it would stop the gas from flowing back to the tank.

[Gjac]

wa8yxm wrote:
Check valve won't help.. I can explain why but.. Well, take my word for it wont' help

Two suggestions: First RTFM.. THe manual for my ONAN says to press and hold the STOP button till the light comes on solid... Now if you do this inside you won't notice anything but the light.. But if you do it outside you will hear the fuel pump clicking when the light is on.. Hold it a few seconds longer.

Then press START

I find this helps. but still. Try this

Press Start.. Let it turn over just once or twice (Cranking not running) NOw release,, count to 10 and press again (longer if you don't do the stop bit first)
Mine genrally fires on the 2nd press...... IF it's been a full month, may take a 3rd press.

I don't have an Onan I have a Kohlar 5kCM21. There is no prime function.

[10forty2]

Don't think my Onan has a prime function either...at least when I press the button towards stop as recommended, nothing happens...can't hear fuel pump, and when you disconnect the fuel line, no fuel comes out until you try to actually crank it over. It usually takes me about 3 tries to crank mine too, and I usually have to hold the auto-choke until it cranks. Once she fires, it runs like a purring sewing machine.

I suspect the gas in the bowl evaporates between uses instead of it running back into the tank from the fuel line. The pump should have a check valve already on it. It runs based on demand from the carb which has a float switch that opens when the level in the bowl goes down due to usage or evaporation.

[96Bounder30E]

JaxDad wrote:
What generator do you have?

Every Oman has a primer, I case every Generac does, but all the ones I've seen have it.

My Onan 4ky does not have the prime function

[wa8yxm]

Check valve won't help.. I can explain why but.. Well, take my word for it wont' help

Two suggestions: First RTFM.. THe manual for my ONAN says to press and hold the STOP button till the light comes on solid... Now if you do this inside you won't notice anything but the light.. But if you do it outside you will hear the fuel pump clicking when the light is on.. Hold it a few seconds longer.

Then press START

I find this helps. but still. Try this

Press Start.. Let it turn over just once or twice (Cranking not running) NOw release,, count to 10 and press again (longer if you don't do the stop bit first)

Mine genrally fires on the 2nd press...... IF it's been a full month, may take a 3rd press.

[Gjac]

enblethen wrote:
If I remember correctly, some Kohlars have a fuel cutoff switch near the carb.

Can't find one one my 5KCM21.

[JaxDad]

Gjac wrote:

waxerk5 wrote:
Before you start the generator, do you have the option to hold down the shut off button and it will prime the fuel pump? Most Onan's have this function, check to see if yours does.

Also, you don't want a bunch of fuel to be in the carb while it just sits not being used. That will cause the carb to gum up and you'll have running problems.

Mine does not have a prime, but you have a good point about gas sitting in the carb.

What generator do you have?

Every Oman has a primer, I case every Generac does, but all the ones I've seen have it.

[crasster]

If your carb has a bowl I assure, the fuel isn't going back into the tank from the bowl.

[enblethen]

If I remember correctly, some Kohlars have a fuel cutoff switch near the carb.