Our genny is misbehaving.

We were hoping to spend the night anchored out tonight. It would have been our first time doing so but the generator wouldn't cooperate.
It runs fine but it won't run both AC's. It ran one just fine for several hours but then it tripped out. Couldn't get it to stay running after that.

But we still had a nice day. Took a break from scraping and sanding and just relaxed. We anchored out and swam and grilled some yummy dinner and just enjoyed the afternoon.

But now we're back home. Boo.

Grilled tuna for dinner.

Just relaxing...

The hubs.

Gensets! More engines to maintain! Most "fully equipped" boats have three engines: two propulsion and one generator. Oh, the horror!

Post what brand/model the gennie is. And post exactly what it did, symptoms, hints, etc. I can probably help. Fixing goobered gennies paid for building my boat!! I won't charge you that much, though!

I would like some of that grilled fish.

Westerbeke 7.5KW gasoline. The engine surges initially after start up and take a few minutes to start running semi smoothly. once we switch over from shore power, no issues with the small loads like lights and AC fans. I turn the AC controls to fan only when switching to the generator.

After making the switch, I move the aft AC to run which kicks on the compressor. Initial surge from starting current and then the generator levels out. Some minor voltage fluctuation but not more than 5 volts.

Kick on the second AC and the whole things bogs down. At least that's what it did today and the last two time we tried. On a couple of previous occasions it handled both ACs with only the initial starting surge and then lined right out.

Today though, while it handled the aft AC ok during the initial couple of hours of running, it bogged down with the second. And then, while we were anchored, it must have surged or fluctuated voltage enough that the aft AC breaker tripped. Turned the AC to fan only, reset the breaker and everything looked ok. Turned it to run (turned on the compressor) and after starting current surge, looked like it lined out. 10 minutes or so later and the aft AC breaker tripped again (presumably on voltage fluctuation). I wasn't watching it the whole time so I don't know if the fluctuation coincided with a refrigerator compressor start or what. All heating elect circuits like hot water heater were turned off so it wasn't that.

I general. I would say there is either fuel filter issue, trash in the carb, or sticking throttle control not allowing the engine to throttle appropriately. It could be the voltage regulator but the surging during initial start with no load makes me think more fuel or throttle issue.

I will add some snapper to the tuna on the grill for a genny fix.

I might have to freeze dry it to ship it to NC though.

Could this be related to the water in fuel problem you had recently? IOW could there be water in the generator filter?

That is a possibility. But in addition to removing the water from the fuel, I had a full service done on all three engines. Now with that being said, the generator fuel filter is a big question mark right now. The mechanics who came service the engines couldn't find one.

i haven't traced the fuel line myself (yet) but will probably do so tomorrow. There is no obvious filter canister on the line though. Of course the main engines only have the primary engine fuel filter as well. No secondary filter/water separator on the lines from the tank. This is on the list of fuel system modifications to be made in the near future.

Sounds like a good project for the winter.

The perils of trying to turn a boat into a cottage on the water...Good luck.

Even if gennie is acting up like surging, it should not trip the aircon breaker. Does aircon work ok on shore power? If aircon works on shore, then I guess it is the gennie.

Gas gennies are tricky. Not only does the governor need to control rpm, but carb has to control mixture unlike a diesel. Diesel just needs to control fuel, mixture is what it is. Much easier to control a diesel.

If mixture is not right, governor can go nuts trying to keep rpm steady. And if mixture is not right, it can foul plugs. Lose a plug and and engine can't make enough power.

First thing is take flame arrestor off and make sure choke is open. With engine running, nudge throttle linkage toward idle to drop rpm, then let it go. It should open throttle and engine smoothly accel, then linkage settle out and rpms steady. If it sputters and shakes, carb mixture not right or bad plug. Try it again giving it a hint of choke. If that improves things, carb is lean and needs work. Note most of these have a fixed high speed jet, so a lean condition means cleaning the carb.

Try disconnecting each plug wire one at a time and see that each has a similar effect on engine. If you disconnect one and no change, no fire in that hole. Try a new plug.

Keep fire ex handy for all this and don't do it if you sense any gasoline smell. Ask your wife to do the sniff test, men's noses no where near as sensitive. But we all know that...

Take the plugs out and check color of insulators. If black, or if it flunked the wire-off test, get new plugs. If black, carb is running rich.

This should be some sort of Japanese or Korean car engine, so plugs are available from auto parts store.

Be very careful!! If carb is running rich enough to make plugs black, that thing is making GOBS of CO. Very dangerous.

Also be careful pulling plug wires on a running engine. High likelihood of getting "bit" by 40kV. Not usually lethal, but will be memorable. If your heart is weak or being run by sensitive electronics, may want to refer this step to a young punk.

If unit runs well, passes the above checks, but bogs say 10sec after successfully accepting load, sounds like fuel restriction. Acid test for this is that it takes the load and runs fine until carb bowl contents, maybe an ounce or two, is burned off and not re-supplied.

Try the above and see what you get.

I'm anxiously awaiting my fish.

AC units run with no issue on shore power.

On more than one occasion I have seen a gas engine that ran fine at low load but died at higher loads due to partially clogged fuel filter. The fuel couldn't get through the filter fast enough at higher load.

Ken

Update on this older thread because we finally got it fixed.
We had the carburetor rebuilt and it is running great now...knock on wood.