Sea Ray

The 5e is a gas unit correct? I have a 7.3 in my boat. I would pull the plugs and make up a solution of oil and gas or use a light weight oil and squirt into the cylinders to lube them from the top. Then turn over the unit without the plug wires. This will lube the cylinders and get any excess oil out of the cylinders. Then I would as Hideout suggested, do a full maintenance. I would replace the oil, oil filter, gas filter, plugs, raw water pump, as a minimum. Check all the fuses in the fusebox. Go online to kolher manuals for a complete maintenance chart if you don't have a manual. I think there are several manuals for that model. Also when you replace the fuel filter, without the plugs in (so it won't start) turn the unit over and pump gas through the line so that when you put everything back together you have fresh fuel at least past the fuel filter.

Since it hasn't been run for a long time the carburetor may need to be rebuilt, due to damage from the old gas that may still be in the carburetor. I hadn't run my generator for 2 years. When I tried to use it during the 2019 boating season it wouldn't start. When I had the boat winterized at the end of 2019, I learned that the old gas left in the genny caused a need to get the carburetor rebuilt. Going forward I'll be sure to run the genny at least once during the boating season. Good luck with your genny.

I agree with LovesBoating that an engine that hasn't run in 12 years more than likely has a carb that needs to be taken apart, rebuilt and cleaned. If you are a DIY'er you can try to drop the bowl and clean the heck out of everything you can spray with carb cleaner. Then reassemble and keep your fingers crossed.

Just to add if you get it running and it's running rough, try adding SeaFoam to the gas to help clean the carburetor. If your engines are fuel injected you should run a tank with the additive to clean the fuel injectors at least once a year.

I can guarantee after 12 years the fuel in the carb, fuel line and filter have turned to varnish. You can try cleaning but what's your time worth? Pull the plugs and put an oz of Miracle Oil in each cylinder and leave for a day. Before you attempt to turn over. You don't want to scar the piston wall or worse yet bend a lifter and piston arm...
Also, injectors are more than likely plugged.

I recommend caution with adding SeaFoam or any other additive to your gas, without first determining what additives are already in the gas. You don't want to compound the issue. Many marinas add a bunch of different additives to the gas they sell. Depending on your marina, their gas may already include an additive that serves the same function as SeaFoam. I think you have a bigger question to answer before proceeding. How comfortable are you with tackling the job yourself? If things go south are you okay with the additional costs you'll incur to correct the problem(s)? If you're not a big risk taker you may be better served by paying a qualified boat mechanic to get the genny up and running. That way the risk of not getting it done right rests with the mechanic or marina. You also get some type of warranty with having a qualified mechanic performing the work.

Yes, the 5E is a gas unit. All great suggestions, thanks for the feedback. I agree the carb will need a rebuild or replace, along with all the regular service kit items. I downloaded the service manual and it looks like I can do all of the maintenance tasks. Thx again for all the suggestions. I'll post a follow up when I get it running (although it will be a number of weeks before this gets to the top of the to do list.!).

The Kohler 5ECD in our ‘07 320DA is fuel injected, therefore, there is no carburetor. I would not recommend dumping any liquids into the cylinders, a shot of fogging oil is the proper tool for the job. Next, I’d change the fuel filter and bleed the old, stale fuel out of the system via the Schrader valve on the fuel rail. There’s a button sequence on the 5ECD to run the fuel pump without starting the engine, to facilitate this procedure, it’s documented in the 5ECD service manual that can be found online. After you get it running long enough to reach operating temperature, I’d change the oil and filter, check the impeller, check the heat exchanger anode and change the coolant. If all of this sounds above your comfort level, I’d leave it to a Kohler certified mechanic.

All good comments TandE. One more thing is behind impeller is a plastic shatter coupler. Meant to break if engine is under stress. Usually yellow plastic. Check it is intact.

Based on my experience. just call Kohler directly and have them come and service it before you try to start it for the first time. Most generators don’t get enough use and they suffer from similar issues. Don’t bother waiting for a marine mechanic, they are too busy.
Kohler is very responsive and they have service techs on the road.