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Old 05-18-2018, 04:18 PM   #1
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New Onan 4000 question

Teaman here. ............ I have been running the Onan generator about 20 min each month and all has been fine until lately the Gen will sputter and die after several minutes. Will crank and start later, but still only runs a short while. I immediately thought of water in the gas line or carb. But looking over the manuals, I have some question about the carb bowl drain. The diagram shows an arrow to just below the 'Altitude' adjust knob. And the manual says it is a screw.


I found a Philips screw at that location, but when I unscrewed it, it turned out to be a 'Needle Valve' type screw with a point end and a spring around it. It looks like some kind of mixture control or something. I took it all the way out and I saw only a little gas drip down.



Is this the real drain point, or am I monkeying around with something else? I put this screw back in and tightened down completely. Then I started the gen OK. But it again only run about a minute before chugging down.


Anybody got any experience with this generator? I could use the help.
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Old 05-18-2018, 08:59 PM   #2
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See pages 44 & 45 to assuage your concerns:
https://www.norwall.com/product_pdfs...015.pdf#page21
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Old 05-19-2018, 08:27 AM   #3
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I will throw out my limited experience with this generator.

My generator would run rough and surge a lot but did not die like yours does. There are some videos on the web regarding a seafoam cleaning. It involves removing the fuel line and running off a mixture of gas and seafoam for an hour or so. It made a big difference on my generator.

Later on, my generator got difficult to start. There is an arm that attaches to the carb that was sticky... I think that the choke did not engage. Perhaps your choke is stuck on all the time. I just wiggled the lever a few times and then it moved freely.

I hope this might help...
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Old 05-19-2018, 08:46 AM   #4
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Sounds like a fuel pump/filter/float problem. 2013 is pretty new and you have been running it. I would be surprised if it were water since the generator fuel connection is well above the bottom of the tank (1/4?). Can you hear a metallic sound from the fuel pump? If so it is starved or sucking air somewhere...or just bad. If you take the line off the carb and put it in a jar and have press and hold the stop switch down on the generator it will run the fuel pump and you can see if you are getting any fuel pressure to the carb.
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Old 05-19-2018, 08:59 AM   #5
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A needle valve like you removed should not be tightened down completely I would back it out between .75 and 1.5 turns and try again.

How old is the gas in the tank ? is there any sort of additive in it ?
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Old 05-19-2018, 10:19 AM   #6
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Teaman here. ............... Thanks for the replies. Funny thing. Yesterday I posted a reply to Duckogram and thanked him for his post and helpful tip. Now I can't find that reply on this thread? Guess it went somewhere else.


In any case he supplied me with a link to an Onan Gen. Manual. It had an illustration of the part of the carb. containing the Altitude control knob and a Phillips head screw in greater detail than the manual I was using. The arrow clearly pointed to that screw that I had loosened and taken out. So I was diddling with the correct 'drain' screw alright. I'l have to try that bowl drain routine again.


Thanks for those extra tips. I'l look into those angles soon. Maybe I have allowed the fuel to get contaminated with 'condensation' water. The MH has been sitting about six months, and I tried to run the truck engine and the Onan once each month. Maybe not enough. The manual from Duckogram said I should have run the gen. much longer each month.


The MH gasoline tank is about 3/4 full so there is enough room for air to allow the dreaded condensation to form. It was standard practice when flying airplanes to walk around pressing all the drain cocks on the wing tanks and the carb. before each flight. Sometimes a lot of water would dribble out before the gas would.
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Old 05-19-2018, 12:33 PM   #7
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The automatic choke linkage was stuck (off) on My 4000 with under 30 hours on it. Was very hard starting form day one. I fixed it by loosening the set screw on the choke assembly and turning the adjuster counter clockwise until the linkage released. When the engine is completely cool the linkage should move freely.
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Old 05-19-2018, 04:41 PM   #8
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I had a similar problem with my Onan 5500. Took it to a service center where they removed and cleaned the carb. It had sticky residue built up.

They suggested I run the genny 45 mins at least once per month. And, when you run it make sure there is a load like the AC. I do that now and the genny has been very reliable since then.

Bill
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Old 05-19-2018, 05:53 PM   #9
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Onan 4000

Add stabeliser in the gas tank (red Stuff)
if your gas is sitting more then 2 monts in the tank.
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Old 05-19-2018, 08:29 PM   #10
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gen

it only use abt 1/2 gal a HR under no load need to run lot longer at least a HR w/AC on need load to keep carb clean
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Old 05-20-2018, 08:36 AM   #11
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If your 4000 is new you should contact ONAN !!!
Last year we had to have our carb replaced in the Spring & the Fuel Pump replaced in the Fall,,, Ethanal fuel is very hard on ONAN generators !!! Cost of about $800 !!!
Our MH is a 2013 !!! I would suggest you keep a treatment in your fuel,,, like Seafoam,,, and when in storage use BLUE Sta-Bil !!! And exercise longer ???
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Old 05-20-2018, 08:38 AM   #12
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Quote:
Originally Posted by santara View Post
it only use abt 1/2 gal a HR under no load need to run lot longer at least a HR w/AC on need load to keep carb clean
Generators should be Exercised under a load !!!
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Old 05-20-2018, 05:25 PM   #13
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onan 4000

You could use Hi Octane gas for the generator in the future, it will not clog your carburator in the future and dont forget to add the stabeliser now .
If the gas in the tank is more then 6 monts, add additive also to the gas tank and run the generator to empty the tank.
Then start fresh with Hi Octane gas.
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Old 05-20-2018, 06:15 PM   #14
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Quote:
Originally Posted by Jonol View Post
You could use Hi Octane gas for the generator in the future, it will not clog your carburator in the future and dont forget to add the stabeliser now .
If the gas in the tank is more then 6 monts, add additive also to the gas tank and run the generator to empty the tank.
Then start fresh with Hi Octane gas.
The genset is not freestanding. It draws its fuel from the MOTORHOMEs fuel tank. All 55* US gallons of it. So whatever you put in the gas tank needs to be good for the 6.8L V-10* as well.

* Unless the OP has a Chevy in which case, I’m so sorry.
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Old 05-20-2018, 06:29 PM   #15
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Quote:
Originally Posted by Wolverine 1945 View Post
Generators should be Exercised under a load !!!

Quote:
Originally Posted by santara
it only use abt 1/2 gal a HR under no load need to run lot longer at least a HR w/AC on need load to keep carb clean

Don’t ya just love “Emphasis Added”
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Old 05-20-2018, 06:33 PM   #16
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onan 4000

Then, you still could use Aditive and Stabeliser with regular gas and at the end of your camping season, keep the tank low in gas and when you store it add 10 gallons of hi octane gas plus stabeliser and your good for 6 monts.
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Old 05-20-2018, 06:41 PM   #17
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Oh my! Congratulations Sir, you are #25.
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Old 05-21-2018, 08:35 AM   #18
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I do not believe Hi Octane fuel is the answer,,,
The answer is Ethanol Free Fuel !!!
Can't imagine what that must cost these days ???
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Old 05-21-2018, 08:37 AM   #19
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I do not believe Hi Octane fuel is the answer,,,
The answer is Ethanol Free Fuel !!!
Can't imagine what that must cost these days ???
Or ONAN could build a Generator that could handle Ethanol !!!
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Old 05-21-2018, 09:21 AM   #20
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Or ONAN could build a Generator that could handle Ethanol !!!

They do...EFI...


https://www.empowergenerators.com/pr...8-5-5kw-45-8a/
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