Odd Genset Issue, help needed

[jryotas]

So our 2008 Cobalt has a weird issue where the generator runs and runs fine but only for about 2 or 3 hours. When it dies, it will not restart for at least 30 mins. Oil pressure is always around 60 , temp is just aver 200 per the manual gauges on boat. The gen is a kohler 5e . We have replaced spark plugs, bled internal cooling sys, lots of water coming from exhaust exit and inpellar was changed les than one year ago and prob has less than 20 hrs run time on impellar. Total hrs on gen is about 250. Banging my head on this one as most of the issues I have seen happen within the first 5 to 10 mins or less but this one runs and runs fine for hours and then just shuts off and starts draining batteries if not restarted in 30 mins or so . Im am hoping someone here can point us in the right direction.

 

[alldodge]

So our 2008 Cobalt has a weird issue where the generator runs and runs fine but only for about 2 or 3 hours. When it dies, it will not restart for at least 30 mins. Oil pressure is always around 60 , temp is just aver 200 per the manual gauges on boat. The gen is a kohler 5e . We have replaced spark plugs, bled internal cooling sys, lots of water coming from exhaust exit and inpellar was changed les than one year ago and prob has less than 20 hrs run time on impellar. Total hrs on gen is about 250. Banging my head on this one as most of the issues I have seen happen within the first 5 to 10 mins or less but this one runs and runs fine for hours and then just shuts off and starts draining batteries if not restarted in 30 mins or so . Im am hoping someone here can point us in the right direction.

Can you elaborate a bit more of how the Gen starts draining batteries?

 

[jryotas]

When it dies with all the accessories on, it will drain down pretty quick. If I left the gen breaker on without the gen running , it drains the batteries. Im figuring this is normal though due to the inverter still trying to run

 

[alldodge]

Does it drain as fast when the Gen was never started?

 

[Scott Danforth]

I would guess fuel vapor lock. next time it dies, put an icepack on the fuel line just prior to the carb (after the fuel filter), as well as on the fuel pump. after 5 minutes, try it. The Onan gensets used to suffer this issue, then a pre-pump and post pump fuel cooler was installed.

 

[jryotas]

Not sure your question as we usually dont flip the gen breaker unless the gen is running.

Another note, water coming out exhaust port is not very warm . I am leaning on a faulty exhaust temp sensor ?

What should the temp gauge be reading ? Im pretty sure it has always been right at 200 .

 

[alldodge]

The Gen breaker should make no difference on draining the batteries. If it does there is an issue somewhere.

It probably is one of your sensors, and most probable is the exhaust and water temp. All the sensors work by grounding out, other then the 12V and 120V. After it does it remove the wire one at a time on them to see if it would restart.

I'll go look at my Kohler manual to see what it states about temp range. Mine doesn't have a gauge