Black soot in generator water exhaust

[lawrence_craig]

Hi there,

I have an old Farymann Paguro 4000 generator. I recently had it fully serviced including a rebuild.

Now it’s been reinstalled I have observed 2 things:
- The water exhaust is loaded with black particulate.
- I can only really take the load up to around 2500W before the generator really struggles

Any clues on both of these? Are they related?

Many thanks

[ItDepends]

It is not generating full power. The black soot indicates partially burned fuel the engine tried to burn, but could not. This is normally a sign of an overloaded engine where it is not sucking in enough air to burn the fuel that is injected. Since we can be pretty sure the engine is not loaded past its design, there must be something wrong with it.

If it has been this way since the rebuild, but not before, then they did something wrong. If it behaved this way before the rebuild they didn't fix the problem.

Lots of possibilities.

• One or more bad injectors.
• One or more cylinders with low compression from poor sealing rings or valves.
• Bad timing on the injection pump.
• Bad valve gaps.
• Bad injection pump.

I'll bet people here can come up with more.

When somebody screws up a rebuild, it is always a difficult decision on how far to let them try to work out the problems they caused. But giving them at least one go at it seems reasonable.

[Sailmonkey]

The Pag 4000 is a single cylinder faryman engine I believe. The injector timing on those things is a pain, but needs to be spot in to generate the needed power to run under load.

[Rumrace]

If it’s just rebuilt the rings haven’t set yet. Better crosshatch or the rebuilder left a lip. Sounds like lube being burnt.
We’re your injectors rebuilt they can cause soot from too much fuel. Are the valve guide seals new if it’s a 4 stroke.

[skipperpete]

Do the easy stuff first, check the valve clearances, take a look at the aircleaner if you have one and check the exhaust backpressure,..... a blocked exhaust or mixer elbow may cause the soot you describe.
Avoid adjusting the throttle/ Governor linkage, poor adjustment leads to overspeed and over frequency.
Are you sure about the load, could it be more than 2,500W.... how do you measure this? Could one of the connected appliances be failing and overloading that tiny little engine?

[thesaltytar]

Good suggestions above. I would start at the air filter because restricting this will result in overload condition. As stated, easy stuff first. Does it smoke at idle or light load?

[lawrence_craig]

Thanks all, will have a look into the above.