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Old 03-08-2011, 12:45   #1
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Generator Troubles

I have a 1984 Kohler 8.5kW, (gas). It starts easily, but will run for a few hours with light loads, but only a few minutes with any serious load, (1 * 15 amp A/C). It should have planty of power to run the entire boat, (and it can for a few minutes )

I have checked the obvious , cooling, pumps, plenty of water flow, I have replaced the heat exchanger, and entire exhaust assembly. spark plugs, oil, distributer, etc...

I have cleaned and reassembled the carb, but there are several parts like the fuel reclaim that no longer work, I had to replace the governer spring, and did my level best to adjust to factory specs, it also has an add on electric fuel pump as the mechanical pump also is broke..

I am down to exhausting my level of mechanical skill, I have considerable electrical skills, but I am middle, at best, in mechanics. The voltage and current under load, and frequency, (60 hertz) is fairly stable.

My choices as I see it are,
1. Get additional technical help and keep trying.
2. Hire a professional Kohler rep to repair, or overhaul unit.
3. Buy a new generator.

Option 2 has no guarantees and may lead to option 3.

With most of the incidental loads on the inverter, the only thing I need the generator for is the two 15K BTU A/C units, stove and hot water heater. And battery charger.

Any ideas, or a good source for a cheap replacement, (used?), would be appreciated, thanks.
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Old 03-08-2011, 13:30   #2
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Re: Generator Troubles

Capn Bill:

I would take another look at the fuel system. Gas engines are more tolerant of fuel problems than diesel, but yours may be the one.

First is your fuel filter clean? If you are not sure, then replace it.

Then if the problem persisits, buy a fuel squeeze bulb like you see on outboard fuel supplies. Splice it in the fuel line just before the carb. Use clear tubing on the output side so you can monitor for bubbles. Pump it up hard, start the engine and squeeze it every few seconds to keep it hard while you put a heavy load on the genset. Hook up some temporary resistance heaters if you have them to really load it. Put at least 6 kw of load on it.

If you feel the bulb getting soft, that is an indication that your electric pump isn't doing the job.

You should be able to keep the engine going at full power with the squeeze bulb even if the electric pump is kaput. If you can keep it running with the squeeze bulb then you have a problem with your electric pump, or your fuel line or the fuel pickup inside the tank.

If you can't keep it running then I would look at shutdown interlocks tripping- oil pressure, temperature or alternator output.
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Old 03-08-2011, 13:32   #3
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Re: Generator Troubles

Kohler Generators generally have high water temperature, high exhaust temperature, low oil pressure, and loss of seawater cutouts, and (perhaps) a carbon monoxide cutout.
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Old 03-08-2011, 17:53   #4
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Re: Generator Troubles

Some very good advice above. On the theme of your fuel supply, what kind of tank does the boat have? Have you put any gas with ethanol into your boat recently?
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Old 03-08-2011, 18:42   #5
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Re: Generator Troubles

As gord says...... Try bypassing any of those...
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Old 03-08-2011, 20:18   #6
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Re: Generator Troubles

We have a 13 Kw diesel Kohler generator onboard and a few months ago, we encountered a similar problem. Fortunately, we have a computer management system connected to the workings of the generator and it reported a high cooling water temperature. We found that the water inlet (skin fitting) was clogged up with barnacles and marine growth. We cleaned this up and everything is running smooth since then.

Our Kohler generator is driven by a Yanmar marine engine and we used them to service the engine. I do not know about your specific generator, but it might use another brandname engine similar to our situation. If I were you, I would certainly call the Kohler technicians to trace the fault.
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Old 04-08-2011, 08:35   #7
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Re: Generator Troubles

I replaced the fuel pump and the filter first. Yes all the gas here has ethanol, I put stabil in it, thats the best I can do. (the generator was made for leaded gas with the old style carb).

There are no lights or warnings, just an old rusted relay box on top. I've thought about putting lights on the relays so I can see which one popped.

As a 30+ year old generator it just may be time to let it go.

The water flow is great, if it's overheating it has to be from another source. I've opened the hoses and seastrainer, and shoved a coat hanger down the tubes to check for obstructions. Both the the exhaust outlet, and the heat exchanger have good flow. I'll check the water temp with a surface probe this weekend.

When it dies, I just turn it off wait a few seconds, and restart it, and it starts right up, for 30-40 seconds, then dies again.
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Old 04-08-2011, 09:03   #8
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Re: Generator Troubles

The earlier suggestions about the fault circuits should help you. My 7.5 has them all "or'd" together so separating them is not easy but you should be able to at least disable the summing circuit that doesthe shut down.

The 7.5 unit and maybe yours also uses a timer to allow things to stabilize before activating the faults such as the oil pressure during startup. If there is a fault, the unit will run just as you describe for about 30-40 seconds and then shut down.
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Old 04-08-2011, 14:44   #9
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Re: Generator Troubles

We have an 8kw Kohler - diesel powered, and as noted above, you will want to troubleshoot your sensors, and for less than $1000, Kohler will test your electronics for you if you send them the board.

Since you've said you've put ethanol fuel in the boat... Any chance you have a fiberglass tank? If so, this is a HUGE problem.
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Old 05-08-2011, 09:18   #10
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Re: Generator Troubles

Quote:
Originally Posted by bstreep View Post
We have an 8kw Kohler - diesel powered, and as noted above, you will want to troubleshoot your sensors, and for less than $1000, Kohler will test your electronics for you if you send them the board.

Since you've said you've put ethanol fuel in the boat... Any chance you have a fiberglass tank? If so, this is a HUGE problem.
Same fuel tanks as the main engines, (stainless), not to say a jet in the carb couldn't be clogged by something, The jets in the main engines are WAY bigger than the little generator carb.

A professional carb rebuild probably wouldn't hurt. I've already taken it apart, and sprayed everything with carb cleaner and replaced float and seals).
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Old 05-08-2011, 09:51   #11
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Re: Generator Troubles

A friend had the same problem with his 7.5 Kohler last week. I got involved checking the fuel pump along with some other stuff. I found the electrical fault to be a very simple problem but hard to notice.

The connector attached to the wire from his temperature sensor was touching one of the cylinder head bolts. It was not obvious, both the head bolt and the connector had the standard paint on them that Kohler uses. It is the simple stuff that can get one to spend hours trouble shooting. We simply pushed the connector away and taped it.
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Old 05-08-2011, 10:11   #12
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Re: Generator Troubles

Besides all the "mechanical" things to check - see if the generator has an output c/b (or switch) on its electrical control box. It is not uncommon for that c/b (or switch) to be worn and constantly tripping when a load is applied. IMHO, it does sound like more of an electrical problem in the control system than an engine mechanical problem.
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Old 13-08-2011, 13:51   #13
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This is a older thread and the problem may have been cured. If not you may check the fuel anti-siphon valve & if there is a screen on the fuel pick-up tube it may be partially plug. It may be starving for fuel as a bigger load is applied and the govenor increases the throttle to maintain rpm.
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Old 14-08-2011, 09:15   #14
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Re: Generator Troubles

Blow out your fuel lines.
Sounds like it's starving when flow increases.
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