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Honda, Yamaha, Kawasaki, Isuszu Generators

Yanmar Knockoff Runs Rough


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  #1  
Old 10-23-2017, 05:29:49 PM
bill42mb bill42mb is offline
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Default Yanmar Knockoff Runs Rough

I recently picked up one of the Chinese made "silent" diesel generators, possibly 6500 watt, powered by a yanmar clone. Checked the frequency and found it to be 55- 56hz, and according to a manual I found online, the frequency is adjusted by increasing the engine speed, which was easy enough.
But- when I do that, it starts to run rough and stumble. Runs just fine putting putting out the lower frequency, but I don't want to damage my furnace, fridge, etc.... I've never worked on these small air cooled diesels, Detroits are more my thing. Could it be a timing issue? To put it bluntly, the chinese manuals are crap (like the engines?) and don't offer much insight. Any input would be great!

Bill
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Old 10-24-2017, 12:07:50 AM
richard.bessey richard.bessey is offline
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Default Re: Yanmar knockoff runs rough

at 55 hz, when you give the genset a big load, lets say a heater type of load, does the engine stumble? If so I am thinking possible fuel problem (clogged filter, injector, etc...)
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Old 10-24-2017, 11:07:30 AM
bill42mb bill42mb is offline
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Default Re: Yanmar Knockoff Runs Rough

It runs fine with a large load, even to the point of when it starts to make black smoke. That's why I'm a little lost with this right now, it runs great, but a bit too slow.

Bill
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Old 10-24-2017, 12:31:26 PM
s100 s100 is offline
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Default Re: Yanmar Knockoff Runs Rough

Don't know anything about these engines but looking at your issue from a general perspective, I can think of at least one thing that could cause what you are seeing. That is, timing off. If the injector fires too late, the fuel may not have enough time to burn completely at higher speeds. Another issue could be a weak or leaking injector. That would be pretty much the opposite of the above problem. A weak or leaky injector could pop off too soon, causing firing before the piston makes TDC. But it seems to me this problem (faulty injector) would be more likely to manifest itself at low speeds and get better as the engine speeds up. But things don't always do what you would expect them to do. The injector and the timing are where I would begin my diagnosis.

As a part of this find out if the engine has some sort of mechanical timing advance for the injector pump, and that it is working properly. Sorry I can't offer any specifics to that engine.
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Old 11-12-2017, 09:37:02 PM
bill42mb bill42mb is offline
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Default Re: Yanmar Knockoff Runs Rough

Posting for anyone interested in the outcome, I removed the injection pump and made a new shim .004" thinner than what was in there. It improved how it ran at the slightly higher speed, and now measures 59.5 Hz
(as opposed to 55 HZ) when at 100% of the rated load. I found a yanmar manual which stated that .004" equals 1 degree of timing change so I thought I'd go with that.
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Old 11-18-2017, 07:15:57 PM
Newoldstock Newoldstock is offline
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Default Re: Yanmar Knockoff Runs Rough

Your could spill time it to be sure.
There may be timing marks to indicate the correct injection point for more than one RPM range.
I am not familiar with these clones but I have worked on Indian clones of Lister/petter.
Those use shims to raise/lower the IP to retard/advance timing.You may have an engine that required some timing adjustment with shims too.

3000 to 3600 rpm is not a big leap.
Timing should be the same for both ( I would think )
Maybe you have a bad pump or injector.

OOPS:
I should have read all the replies.

Shims are your friend....
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Old 11-18-2017, 10:07:05 PM
Newoldstock Newoldstock is offline
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Default Re: Yanmar Knockoff Runs Rough

I drive Toyota F70 trucks at work.
My employer imports them and uses them in the mines because they are dead reliable and do not have to pass any emissions regulations once underground ( Advantage cancer... no pension to pay the peasants but I digress )

65 is an old lady I drove a lot and she was saved from the scrapper because they needed more wheels at another mine.
At some point in the past I know 65 has a replacement injection pump installed and I know the timing is off.
65 was a recycled unit made from all kinds of bit pieces and parts ( has one vent window on the left door but non on the right HA HA ).
Look under the hood and there are parts from several different 70 series trucks all rigged together.
It runs flat around 3500 rpm and will not increase rpm under load.

Some of the new units will go as fast as 70 kph in low range as will some of the older units the mechanics use ( they have the fastest Toyota I wonder why... )

So I ask a chum about it and he said flat out they do not spill time them or even check when the change the IPs out.
You get what you get.

SO the lesson is check your timing even on a diesel because you leave a lot of power behind it it is out.
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Old 01-04-2018, 03:14:03 PM
doctle odd doctle odd is offline
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Default Re: Yanmar Knockoff Runs Rough

I have just bought a Yanmar L48 engine fuel pump is bad. I tried a fuel pump from a Chinese 178F but it won't start or even pull over, I thought those fuel pumps were all the same???
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Old 01-06-2018, 06:24:05 PM
nblack nblack is offline
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Default Re: Yanmar Knockoff Runs Rough

Quote:
Originally Posted by doctle odd View Post
I have just bought a Yanmar L48 engine fuel pump is bad. I tried a fuel pump from a Chinese 178F but it won't start or even pull over, I thought those fuel pumps were all the same???
what do you mean by "pull over"?
No, the pumps are NOT all the same. You need a pump from an equivalent Chinese unit to sub. Start with the original #(thickness) of shims. The pump volume varies by the displacement of the engine. Also, you may already know this, but make sure the rack for the pump fits in the governor slot, and doesn't fall outside the window- else you wind up with a no shut off situation (runaway) or, no fuel. The 178 is expecting to fuel 18.06 cu. in., while the 170 is fueling 12.88 cu.in. <- yours is similar to this one (L48)
Have you talked to the gentleman at http://ezapu.com to see if he can get you the correct pump?
regards,
Noel
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