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Drechsler345

Onan cckb engine problem

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Drechsler345

hello all together,

I am from Germany and hope to find some help in this forum. I have a Hako gardentractor with Onan cckb engine. In last days I got a problem with the engine. In full throttle and under load it seems to me like it has backfire. I have already checked points and condenser. and replaced sparks with new wires and plugs.

then I have made a video from how the engine runs and loaded it up on YouTube. probably any of you has an idea how to repair it.

Here is the link:

thank you in advance for your efforts!

Bene from Bavaria :-)

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Rick3410

When you say you checked points and condenser, what exactly did you do? Bring your idle up and try adjusting the points a little to smooth it out. It sounds like it's skipping from timing. I don't think it the carb, but it could be. I'd make sure the points are clean and check the quality of the spark with an ignition tester. That will allow you to get the proper point setting as well.

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powerking_one

Bene,

Greetings.

From listening to this engine in your YouTube video a couple of things come to mind:

This sounds like a fuel system/carburetor issue (based on how the engine slowly dies out at wide open throttle). Also at initial idle, it sounded like it was running on only one cylinder. Did Hako use the Onan factory mechanical fuel pump or is there an electric one? The Onan mechanical pumps are known (due to use & age) to rupture the diaphram (gasoline leaks into the crankcase usually). Perhaps check the fuel pressure with an in-line "T" fitting at the carb inlet; it should be in the 2-5 PSI (0,138 to 0,345 bar). There may be a fuel restriction from the tank to the carb (like a clogged filter, kinked hose, debris in the tank/pick-up).

Check the ignition timing as well, I believe the spec is in the 20-23 degrees BTDC.

Good luck and let us know what you find...

Tom (PK)

Did this running problem happen all of a sudden with no prior issues?

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Drechsler345

hello Tom and Rick,

thank you for your very quick answer! it seems to me that you are the right guys to get a hang of this problem.

I have forgotten to mention that I have changed to fuel pump to an electrical one. The diaphragm pump was rotten and gas diluted the engine oil. but the problem started before this change. It began while driving up a small hill and a few starts later it was not possible to work on.

I have renewed the fuel pump from tank to carburetor, too.

I tried to check the ignition timing but my ignition lamp is not working.

Here in Germany the

support for such old engines is in need of improvement. and parts are very rare and expensive... :-(

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powerking_one

Bene,

To more quickly eliminate a fuel delivery issue to the carb, perhaps use a temporary fuel tank and hose to it (the carb) say about 0,5 to 1 metre above it (gravity feed) and see if the symptoms/problem change. Of course disable the electic fuel pump first.

This problem could still be a dirt/debris or other internal problem within this Zenith carb.

Tom (PK)

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acfarmer

Not about the engine but I have a Hako Boy tiller I haven't been able to find out much about does the company that makes your tractor also build tillers?

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Drechsler345

yes, the company makes many garden machines and does still exist. its office is close by me. What information to what type do you need?

quote:Originally posted by acfarmer

Not about the engine but I have a Hako Boy tiller I haven't been able to find out much about does the company that makes your tractor also build tillers?


id="quote">
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Kenh

An "old" small engine mechanic once told me "90% of all carburetor problems are electrical in nature". Take this for what it's worth.

Ken

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rickf

I caught the end of the video first, sounds like it runs ok there, just starves for fuel. If you have a clear plastic filter in line, look at how much gas is moving through there, though it sounds like you have a new pump... I'd also try maybe taking the air filter off, and adding some gas with a pipet or such when it's dying. (plastic disposable pipets seem get a lot of use around here for tinkering on motors) See if it comes back up to speed with the extra gas. The uphill bit might go with bowl/float issues in the carb. I always consider air as part of the fuel (no air=no fire) - tractor looks clean but make sure the air filter isn't blocked.

Listening to the beginning, it sounds more like a mis-fire.. could still be a loose Electrical connection that's off/on?

Rick

let us know how it turns out.

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Drechsler345

I have checked the spark plugs yesterday.

There is an ignition spark at every spark plug.

Then I have touched every linkage which runs to the carburator.

Also I have pushed the choke once again and found out that the linkage of the choke does not close fully. There is 1-2 mm I have to pull back by hand. Then I started the engine and worked a few minutes with the mower and had no problems. But if I open the choke only a bit and push the engine on full throttle it coughs like in my video. I do not know if the problem is solved but until now it seems so...toitoitoi :-) If it is it was an easy fix. But I will try again in the next days...

Meanwhile thank you very much for your efforts !

This forum went into my bookmarks ;-)

nice weekend and regards from germany

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powerking_one

Bene,

At this juncture, I would recommend removing the carb and inspecting it for debris in the float valve area and main jet passage. Perhaps when you did the electric fuel pump retro-fit, "something" got into the carb causing restriction in the jet(s). Does this carb have an adustable high speed needle on the bottom of the fuel bowl? I believe on later versions of the Zenith carbs they were fixed jet only.

Tom (PK)

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Drechsler345

Okay, I will check the carb for debris, too. I think it would be the best. But will I need new seals for the carburator if I remove it and check it ? Because it would be a problem getting new seals here in germany.

In the next three weeks I will be on holiday in USA ;-)

California is calling :-)

After this journey I will write down what I have found out.

Thank you !

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powerking_one

Bene,

Here are vendors on eBay who is selling the Zenith carb kit parts:

http://www.ebay.com/itm/ONAN-ZENITH-CARBURETOR-KIT-141-0747-CCKB-NH-NHC-/330748407890?pt=LH_DefaultDomain_0&hash=item4d02243052#ht_235wt_681

I would doubt the main jet is "bad", but just might need a new "o"-ring and/or sealing washer; a big ouch for the price of the high-speed main jet:

http://www.ebay.com/itm/Onan-Zenith-Carburetor-Adjustable-Main-Jet-Assembly-CCKB-NHC-141-0712-141-0942-/390627721502?pt=LH_DefaultDomain_0&hash=item5af33a011e#ht_178wt_681

If you are going to be in the U.S. for the up coming weeks (perhaps if staying with friends/family/other relatives, maybe they could transact these types of auctions for you and have them ready for you stash away in your suitcase?

Tom (PK)

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Drechsler345

hello,

sorry for my late reply.

I´m bound to say the usa is a very nice land.

Our vacation was great.

But back to the topic:

I have asked the seller to ship the new seals to one of our hotels. But he replied he didn´t want to ship it to a hotel.

I have used the tractor in the last few days for lawnmowing without troubles. So I think I will check the carburator number to make sure the carb kit fits and order one just to be on the safe side.

I will keep an eye on that problem...but I hope the tractor will

continue function properly.

I have bookmarked this forum in case of further problems ;-)

Thank you very much for your efforts , especially TOM!

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Drechsler345

Hello again :-) !

I have a new problem now...

the onan cckb engine will not start. I have pulled the choke and it starts and sounds normal. After a few seconds the engine stops. After this it will not start again. I have tried put the throttle open, with choke, without choke - nothing.

Probably it is the carburator, now ???

Did anybody had the same problem and found a solution ???

Thank you!

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Willy

It sounds like you may have a blocked fuel line, letting a little

fuel pass but using it up when it starts.

I would loosen the line at the fuel pump and check to see if you

get a good flow, if not blow back to tank with compressed air

Most tanks have a screen in them and they get crud in them and

restrict the flow.

If that isn't it then I would open up the carb, you may have

a piece of your old fuel pump diaphragm blocking your needle

valve.

Good luck

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Drechsler345

hello again,

I am sorry for my late response.

After hours of testing and trying I have found the solution for my problem...

It was the problem I had before, but I couldn´t remember...It was the Choke :-(...

The manual CHOKE did not close completely...the small choke return spring is not strong enough to close the choke completely. I had to push the lever on the carburator and now the engine runs fine...obviously that was the problem (and I hope to get no new ;-))...but if I know where I get help ;-)

Thank you for your efforts !

With kindest regards from germany !

BENE

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