Generator help please

[Fat Charlie]

I don't understand governors at all.  Mine hasn't done a thing that I can think of since he was first elected in 04, but it looks like he's heading for another win this fall.  I'm left scratching my head.

[Henry W]

Hello veggie,

What might be a good thing to do is to pull thr gearcase cover off and check the governer assembly. There is a race for the governer weights (that are bearings) that should slide easily and push cammed plate to move the fuel rack. if the bearings or the cammed plate is sticking the fuel rack will not open.

While you are at it check the race (which is the retainer for the bearings) and make sure the bolts are tight. they were all loose on my engine. I am lucky it did not let loose and destroyed my engine.

The governer works very good on my engine engine only fluctuates around 2 hertz from no load to 7500 watts.

You can try a lighter spring also.

Henry

[Henry W]

Oh,
I forgot to mention to check the linkage to make sure nothing is sticking. Check the pump to make sure it is not sticking also. Make sure the lever on the pump is sliding smoothly in the fork. If not check for rough surface and polish if needed.

Henry

[Henry W]

Another thing that came to my mind is the fuel limiter. On my Kubota is has a spring loaded plunger inside that puts additional pressure on the linkage. make sure it is adjusted properly and it is not sticking.

A good thing might be to remove it completely and do a test run without it.
My S195 does not have a limiter at all.

Henry

[veggie]

Another thing that came to my mind is the fuel limiter. On my Kubota is has a spring loaded plunger inside that puts additional pressure on the linkage. make sure it is adjusted properly and it is not sticking.

A good thing might be to remove it completely and do a test run without it.
My S195 does not have a limiter at all.

Henry

Hi Henry,

Nobody seems to know how to adjust the fuel limiter.
It's not in the manual.
When I posed this question before, I think you advised me NOT to play with it?  

veggie

[Henry W]

Take it off and see if it has a spring plunger on it. if it does take it off and do test runs and see if it corrects your problem. If it has a spring plunger pushing on the linkage it might be to much when running your genset at 900 rpm's and your throttle spring cannot open the throttle enough when load is applied.


Both my S195's came without a fuel limiters from the factory and the S195 I am using works fine. The fuel limiter could be an emissions thing.

Henry

[Henry W]

Hello Veggie,

Here is what I wrote in the other thread.

Personaly I would not mess with it.

But if you want to try messing with it I would try setting it up by running your engine at your required operating speed. Then loading the engine up untill it just starts putting out black smoke and limit the setting there.

Your fuel rack is being limited by somthing.

It could be as simple as to much tension on the throttle spring running at such low rpm's and the spring is collapsed fully when more fuel is called for and it cannot pull the throttle open enough. You might need a weaker spring.

I think one thing you need to find out is if the fuel limiter is the problem at such slow speeds and this means pulling it and putting a blank plate in it's place just for now. It would be one thing to eliminate while troubleshooting.

Henry

[veggie]

Hi Henry.

I think I can do the things you have suggested. Shouldn't take too long.
(Except for that part about pulling off the gear case. I'm not ready to go that far yet)

Before I invest the time, lets discuss the two items.
This is my understanding of the system, please point it out if I have this wrong....

1] Fuel limiter.
It's my understanding that the fuel limiter is there to restrict the governor when the engine goes to full throttle at times of full load. It stops the rack from providing more fuel when extra throttle would be of no help.
For this reason the spring loaded plunger does not come in contact with the governor arm until full throttle is reached.
When my limiter is installed, the plunger resides at the opposite end of the governor travel. About 1" inch away from the idle position. When my engine is at 900 rpm's, the fuel limiter has no effect on the system.

2] Spring tension.
This one is a bit confusing.
On the Changfas, the spring is always trying to pull the rack to a higher speed while the governor weights work against it.
Therefore a lighter spring may actually give the governor weights more power over the linkage and restrict engine from speeding up. In my case, the engine already refuses to speed up when load is applied.

I adjusted the preload on my spring (using the threaded adjuster on the spring mount) to A] reduce any play, and B] add a bit more tension so that the spring provides more pull on the lever in the direction of higher rpms.
With this change, I was able to get the engine to run smoothly all the way down to 550 rpm !! (no load of course),
Alas, when I ran the engine at the design point of 900 and applied a bit of load, she slows down :-(
I watch the rack lever when this happend and the engine makes no attempt to increase the speed.

The confusing thing is that 2 weeks earlier, this thing would pull 3kw at 900 rpm and hold speed.  

External linkages are fine. Loose but not too loose, and not binding.


veggie

[Henry W]

I believe you said when the generator loads up and starts slowing down you can move the throttle by hand and the engine will speed up.

Put a load on the generator untill it slows down and look at the governor spring and see if the spring coils are fully compressed. (Touching each other) If they are you need to install a weaker spring so the spring will be stretched more to allow more movement on linkage.

The reason I feel there is a problem with linkage is You said you are not blowing Black Smoke. It seems like you are not getting throttle response.

Henry

[veggie]

Murphys law.....
I bought a bag of 100 assorted springs a few weeks ago from Princess Auto for when I need to replace a spring.
Do you think there is even one spring in that bag which could work on this governor......NO !

I will find something to replace the stock spring. Then I'll try it and report back.

veggie

[Henry W]

The confusing thing is that 2 weeks earlier, this thing would pull 3kw at 900 rpm and hold speed.  

External linkages are fine. Loose but not too loose, and not binding.

veggie

If the weaker spring does not work. And the fuel limiter is not effecting the travel of the linkage then pull the fuel pump and make sure everything moves smoothly. If everything checks out ok then I believe the next thing would be the pull the gearcase cover.

Henry

[BruceM]

Since it was holding 900 rpm under load before, it makes me think the governor weights need inspection- like something came loose and  is binding now.  Veggie already confirmed that the external linkage is free and not binding.

If it was holding rpm under load before, it seems unlikely that the spring is at fault, so that leaves the governor weights and internal linkage as the prime suspect in my mind.

[Henry W]

I wrote this a while back.

http://www.microcogen.info/index.php?topic=285.0

Personaly, I would check out every engine I get made in China. Changfa or what ever brand it is.

If you don't you could wind up with problems.

Henry

[veggie]

**** UPDATE ****

Henry....you were absolutely right about the governor spring.
Thanks very much for that.

The only spring I could find was grossly undersized but I decided to use it to prove the point.
It is obviously too light to use permanently but  it did allow me to test the theory.

After installing the spring I started the engine (with one hand ready on the decompression lever ready to kill it in case of over revving   ).

After is was running, I adjusted the speed to 900 and then added some load.

RESULTS:
At 750 watts, she instantaneously adjusted and didn't even notice it.
At 1.6 kw, again instant adjustment and hardly a change in engine note.
At 2.4 kw, the note changed but again the engine instantly adjusted.
Then the big test.. 3KW (full load)
At 3 kw, the knock increased acknowledging the load but the speed did not change. AMAZING !!!

Pulling 3 kw the exhaust was now gray but the tack showed no change in speed.

Overall the engine was less noisy (much less knocking at all loads) because the governor was allowed to freely adjust.

This is important because it was one of the three criteria for modification when the project started.
1] Flywheel weight
2] Injector timing
3] Governor issues (of which I had no idea what to expect).

Again, thanks Henry for your suggestion to lighten the spring and give it a go.

veggie

[BruceM]

I wonder how the same spring worked fine 2 weeks ago.  That's baffling.