Generator Issue. 1998 Kohler 4kW

Little Ducky

Well-Known Member
Jun 5, 2017
2,652
Dickson, TN / Chattanooga, TN
Boat Info
1998 290 Sundancer
Engines
Twin EFI 5.0L w/Alphas
Kohler 4kW
In the 2 years I've owned this 1998 290 DA I've never really ran the generator for any length of time. Just enough time to do a Keurig coffee or use the microwave for a few minutes.

So I went out for a brief swim and I decided to run the generator and keep the AC running.

About 15 minutes later the generator stops. Can be restarted and then off again in 10-15 minutes. Coolant bottle full (not over heated) and water was flowing nicely out the exhaust. I'll check oil and feel around to make sure everything is snug when it cools off or tomorrow morning.

I do have less than 1/2 tank of fuel on board if that makes any difference....so I was going to top off tomorrow as well and see if that changes anything.

Wondering if the fuel pick up is higher in the tank than the engines?

When the generator shuts down it just sounds like someone flipped the switch to off.

I'll pull out the book and do some trouble shooting tomorrow.

If anyone has any suggestions post them up.

Thanks
 
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Sounds like either an overheat condition or possible circuit board failure.

You can pull the cover on the pub and see if and led’s flash a code.

Yes the fuel p/u for the generator is shallower than the engine fuel p/u’s.

Also it rpm steady up until it shuts down? If rpm varies the voltage regulator will shut down the generator.

But I really suspect an overheat condition which is due to air in the heat exchanger.
 
I thought I had an eureka moment today with regards to my generator issue.

Gave the generator a good once over checking oil, coolant and strainer to make sure those are good to go. Then I found a spring ("governor linkage" according to the manual) disconnected. Once reconnected the generator started like it never did before and found it's idle immediately.

Ran for a few minutes and then I loaded it up by turning on the AC. It took a very quick dip and then hummed away putting out 120v without any "wha, wha, wha" like before. I though it was it...... yes ....... running better then ever.

I celebrated briefly ..... about 10-15 minutes went by then........ brrrrrrrrrrrrrrrrrrump. It shut down like before. :(

So I'm going to order up a new pump impeller this week and change it out. I didn't want to take the plate off to inspect w/o having one on hand.

I'll update as needed.
 
On top of the heat exchanger there is a small plug for for bleeding the air out of coolant side of the cooling system. Remove that plug and check the coolant level inside the heat exchanger. The coolant level should be almost overflowing. If not add coolant through the plug hole, make take several small doses over a period of up to 5 minutes, until full and re-install plug.
Let me know what what you find with the impeller. If the impeller is in bad shape there may also be pieces in the exchanger that need to be removed too.
 
Just did one trouble shooting item last weekend and that was filled the boat with fuel.

Generator still quit after 10-15 minutes of running.

I read a bunch online this week with similar issues and some were fixed by replacing the spark plugs. They are cheap enough so I bought 2 to put in the next time I visit the boat.

I also have:
- Fuel/Water filter
- New zinc
- Impeller/O ring

I'll also look further into the coolant system to see if there is any air in the system to rule that out.
 
Just an update on my generator operating condition:

Things I did so far:
- Changed the impeller (old one was still in one piece)
- Changed anode (old one broke off). Had to push the old one in to install the new. In doing so I had to remove the heat exchanger so I flushed out all sides, removed some old rubber bits from previous old impellers.
- Replaced coolant and burped the system of air. Topped off until it won't take any more while observing coolant circulation.
- Replaced both spark plugs. (Read where this might be an issue)
- Replaced both exhaust temp sensors after finding a broken one.

Generator still only runs for 15-20 minutes then turns off.
Will start right up and continue to run with start button pushed.

Things I'm going to do next:
Add a little more oil (10w40) to see if it solves any pressure issues. (read about this while searching for a fix)
Check / Replace the low pressure oil switch.
Check / Replace the water high temperature switch.
 
Check your generator brushes. If the voltage regulator senses less than 120 volts it will cause a shutdown.
Verify rpms are steady at 3600 - 3700. The rpms can be checked with a timing light that has the rpm function but because the plug wires are shielded you need to splice in a regular plug wire so that the inductive pick up senses the pulses.
You can also disconnect each sensor, oil, water temp and exhaust temp one at a time and see if the run time exceeds previous?
Monitor the operating temp with a infrared heat sensing gun to avoid and actual overheat condition with either temp sensor disconnected.
 
Check your generator brushes. If the voltage regulator senses less than 120 volts it will cause a shutdown.

I guess I needed to add it runs like a champ. RPM's are steady whether it's loaded or unloaded. The voltage indicator reads a steady 120v and when turning on the HVAC it only blips for a second when the compressor kicks in and then back to 120v. Loaded or unloaded it shuts off in the same amount of time.

I'm going to look into the other 2 sensors and then probably turn it over to the local Kohler mechanic the marina uses.

I'm not one to toss parts at something but the sensors are pretty resonable so I have them being sourced to have in hand.

This was the one exhaust temp sensor when gave me some hope.

2019-08-15 17.50.18.jpg
 
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Sometimes it is just easier to put a couple of mechanical gauges on it to see what is going on. The two other safeties are oil pressure and engine temperature. I would speculate that your unit is overheating based on your comments so far. The impeller creates a pressure of around 3 psi in the raw water cooling system.

If the hull intake, strainer or connecting hoses have any blockages.....the pressure will drop and not pass enough water to cool the heat exchanger. After about 15 minutes....the unit will shut down.

Frequently.....the pressure will drop to around 2 psi and still look like it is pushing "enough" water. A tell tale sign of a raw water cooling problem is the exhaust water is warm. The other possibility is that the heat exchanger is clogged which means even with enough water pressure....it can't remove the heat from the engine.

A possible indication that the heat exchanger is clogged is the problem you had with the zinc replacement.
 
When I had the heat exchanger off the generator I flushed both sides out throughly. For what I could see it looked pretty good on the inside. A good bit crap came out of the coolant side so I flushed with water until clear water exited.

The exhaust water is surprisingly just a few degrees above the river water and the strainer is clean.

Now one thing I just remembered when I cleaned the strainer at the end of the season the strainer had 2 gaskets one cork and one rubber...... I removed the rubber one. Even though it's not leaking river water maybe it's sucking some air into the system when the generator runs. I'll track down that gasket and put it back into position when I'm back on the boat.
 
Just an update.

Yesterday I ran down to the boat to do a light winterization. Topped it off with fuel after adding some fuel stabilizer, cleaned out the holding tank and took it out for a spin to get the fuel stabilizer mixed up and to get it into the motors and generator. All running well.

The marina just so happened to lose power so while I was playing on board winterizing the fresh water system I just left the generator run so I could run the heater. It ran like a top for about 90 minutes or so until I was ready to leave last night and it didn't skip a beat.

So what did that tell me?
Why during the summer months would it just run for 20 minutes or so and then power down?

I do have a new water temp sensor and a new oil sensor in hand to install at some point in time. I'm leaning towards the water temp sensor.

Thoughts?
 
If the the generator won't run without holding the start button in, it's a low oil pressure, high water temp sensor, or high exhaust temp sensor, brush/winding issue, or capacitor issue. Usually capacitors fail when it's hot outside or when they get hot. I'd start there for the $15 it will cost you. The Kohler service manuals have really good troubleshooting diagrams. Search online.
 
Im trying to work on my genny while its out of the water and home. How did you get water to it to run it on land?
 
I opened the raw water supply system and put the intake or suction hose in a bucket and the put the house water hose in the bucket to keep it full.
This avoids putting to much pressure in the Cooling system.
 
I was thinking about something like this. Put in top of strainer basket and hook hose to it. Close valve to boat and run water. But now thinking pressure in water might do harm if genny not running. Any thoughts
 
Too much pressure has the potential to cause gasket failure for sure.
Maybe run a hose from the adapter to a bucket and have a helper maintain the water level in the bucket ?
 
Just buy a 3/4" hose to fit your water pump inlet and hook it direct to your hose. Turn the water on just partially. If you've operated and flushed jetskis out of the water, it's at about the same. You're not going to over power anything.
 

I have one of these devices ..... there is an attachment you can buy or make to use a bucket. Might be something to think of to keep the sea strainer full while running the generator.
 
Thanks guys. Have never ran the genny. I have had boat 2 years but sat on land for 7 prior years. Genny cranks but will not start. If i pour a little gas in carb it starts right up then dies. So i know its not blown and runs. Now just trying to track down why it will not start. Figuring a fuel problem. Its a 1998 kohler 4ESZ in a 290 dancer. Fyi thanks sea ray for placement. Fun working on at 225 lbs
 

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