Black soot from exhaust Onan 5500 Generator

[vivusCraig]

I have a gas Onan 5500 Generator which is about 18 months old. It has 70 hours on it. I have run it each month that it has not been used under load for 2 hours. In the summer, with both air conditioners on, in the cooler weather with my fire place and a couple of 1500w electric heaters.

During the last two times, I have run it for maintenance, when it starts up, black soot is expelled from my exhaust. It only happens when it is started.

It starts fine, runs fine but I am concerned about the sudden appearance of this black soot upon firing the genny up.

Has anyone experienced these issues?

[Mopar_Earl]

Fuel injection or carb?


Earl

[vivusCraig]

Originally Posted by Mopar_Earl

Fuel injection or carb?


Earl

It is carb.

[RogerR]

Sounds like it is running rich (to much gas). This is most likely a carb adjustment or repair problem. Check it over visually for leaking gas or any loose parts. Also, check the plug as it may be fouled or defective.

At least a couple of times a year you should inspect the engine for gas and oil leaks, loose bolts on the feet, aging gas lines, loose or leaking exhaust pipe/muffler.

[Mopar_Earl]

Carbs do not burn clean so normal to find soot/carbon in the exhaust. Especially when cold and the moisture blows the soot out.

Make sure air filter is good and nothing blocking the air inlet. If it runs good with no hunting and takes a load like a champ, I wouldn't worry about it.


Earl

[vivusCraig]

Originally Posted by Mopar_Earl

Carbs do not burn clean so normal to find soot/carbon in the exhaust. Especially when cold and the moisture blows the soot out.

Make sure air filter is good and nothing blocking the air inlet. If it runs good with no hunting and takes a load like a champ, I wouldn't worry about it.


Earl

Thanks Earl. Will check the air filter. Hoping to hear something like that. Genny has been running just fine. Didn't want to overlook something if there was an issue.

Originally Posted by RogerR

Sounds like it is running rich (to much gas). This is most likely a carb adjustment or repair problem. Check it over visually for leaking gas or any loose parts. Also, check the plug as it may be fouled or defective.

At least a couple of times a year you should inspect the engine for gas and oil leaks, loose bolts on the feet, aging gas lines, loose or leaking exhaust pipe/muffler.

Thanks RogerR. Being proactive in inspecting the engine is a good idea. I will be taking a closer look to make sure everything is sound.