Kohler 7.3e --- solved (old thread new info)

J

jnova1111

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Kohler 7.3e 117 hrs - carb replaced less than 30 hrs ago.

The gen has been running fine last time I used it about 5 weeks ago. Usually run it 1/2 hr every 2 wks under big load. Last week it stopped sfter 10 mins. Had some trouble restarting it but was able to get it going for another 10 mins then I shut it off. Yesterday attempted to start it again and was able but it had to crank longer than necesary. It ran for about 15 mins than stopped. Restarted it after 2 hrs with no problem but noticed as I increased the load the voltage dropped to under 70v. I then changed the water separator and the gas filter, pulled the plugs they were clean and normal looking, and checked the raw water impeller which look perfect. Today it restarted with no problem and ran well for several mins under full load - and even popped the mainbreaker. I thought this was strange since it has never happen before under full load. Turned off the gen restarted it 2 hrs later ran well under full load canme back 20 minws later motor sounded different with the voltage jumping between 70 to 90v. I stopped the engine and found the heat exchange quite hot. Compression test last year was normal. Any ideas?!?!
 
Thanks for the rely - Yes oil and filter changed 20hrs ago level is correct.
 
Check your fuel.Those Kawasaki are very sensitive to fuel specially with ethanol Replace spark plugs.
 
Thanks. This generator eats plugs for breakfast but these were replaced about 20 hrs ago and looked really good with not discoloration or carbon fouling. I use startron at every fill up about triple the recommended amount and use 4 times the recommeded amount when wintering. The was no water in the gas poured from the separator/filter. The gas looked clear but quite yellow. About 60% of the gas is a year old and 40% was added 8 weeks ago. My 6.2L engines run well.
 
Boatcomfort - problem may be very similar to Bob j's - he stated in another post "Under 20 a no problem. Over 20A & unit will shut down in short order."
 
Probably. I have to call him. Right now, I have something I have to take care first.
 
Update - after checking the spark and making sure it was not the electric fuel pump I changed the plugs as Boatcomfort suggested even though the plugs look great, had low hrs on them, and this was not the ususal way the gen would react when it needed a plug change. 45 mins on full load and it ran like a champ. The only thing different is that it seems to be excessively hunting on no load. Thanks to all who responded.
 
Boatcomfort has been in the Gen and A/C business for a very long time.

He knows his stuff.

He is my genset and A/C repairman for quite a long time now.
 
I would really like to understand what makes those engines so sensitive to spark plugs.

Are those plugs the very long insulator tip type?
 
pdecat

I have no idea why it is so tempermental about plugs. The ones I use are NGK BPR6EFS (I will double check when I get home tonight and advise otherwise if I got it wrong.) I had switched to platinum at one time but when I had the carb replaced the local gen technician insisted it would be better to use a standard plug and replaced the platinums. The platinums had only a few hrs so I never got a chance to fully test them. I been thinking about Iridium and, even though they are costly, it will be a wash if they last. Maybe Boatcomfort can shed some light on this subject.
 
I have same genny and another issue I have had was the air getting into fuel.
No idea why, but sometimes it would get air and have to be bled.
There is a manual bleed on it.
 
If you getting on the the fuel line you can have a bad pickup tube or some connection is loose some place.Bad pickups i had two cases.
 
Plugs running too cold is my guess. If the old plugs look black or dark in color I would consider a hotter heat range plug. When removed after running with a good load a proper plug should look tan in color.

One possible source of the chronic problem is that the engine is too powerful for the generator size. If that is a 7500 watt generator that equates to just over 10 HP but that multi cylinder engine might be 25 HP or so. From the PIX above it is also a flathead and they dont mix fuel and air as well as OHV so it runs a bit richer.

That extra HP is needed to deal with rapidly changing loads but also is being run at low loads meaning low spark plug temperature most of the time.
I looked at some pix and it does appear to be one of the longer thread types. That leads me to suspect it runs too cool and eventually shorts, especially if the genny is run at low loads for a long time. You can usually find hotter plugs but you dont want to go too hot either.

If it was mine I would go up a heat range or 2. Then pul them after some running and look at the color. If they are white back off a range, tan is fine.
 
I had a Kohler 5E that had problems that were always fixed by replacing the plugs. I don't recall the specific number, but I finally switched to a slightly hotter plug which helped -- a lot.
 
pdecat You are right. I talked to technical assistance with Kohler and they gave other spark plug # which I can't find on my notes.The only I remember was on the Kawasaki engines stay with NGK's.
 
The Gas newer ECD versions of Kohler seem to have some issues. I have to admit though Kohler has straightened out every issue. 1st issue I had was a software upgrade. 2nd issue we ran the boat very low on fuel the genny fuel starved. From that point on it would only run intermittant like it had a mind of it's own. But I kept running it. It was air in the fuel rail like Dave said. However because I ignored the problem both my fuel pumps were replaced (damaged from overheating due to air). They only charged me a trip charge no charge for the parts or labor even though I created the problem that damaged the fuel injector pumps. The 3rd problem is plugs use the correct NGK plugs. I purchased 4 from Kohler to keep as spares.
My model is the 7.3ECD LOW CO model the same as Dave's. I also have the digital remote that is in the Salon. If it detects CO it will shut the genny off, it's a nice feature. It also gives readings like oil pressure, FWC water temperature, Hz, AC volts, hours and RPMs. However after 3 days of inactivity the remote and generator go into sleep mode and the only way to get the remote to work is to manually flick the switch from Auto to Stop back to Auto on the generator. I'm told I can hook up 2 wires to my old Gen switches on the boat's main panel and reset the genny from the salon instead of in the ER. I just haven't done it yet. Thier tech support has been fantasic for me.
Bill
 
I'll try a hotter plug next plug change - thanks for the suggestion. The big lesson I learned was to spend the $6 for a plug change when the gen acts up even if does not appear, or should not be, related to the plugs.
 
Awoke this thread in case anyone searches for any key words therein. Same problem as in the past, generator running with no problems last season and at beginning of this season then all of a sudden it starts hunting and becomes worse as days pass (all filters had been changed at start of season.) Changed the plugs using autolite plugs but generator still hunting. Took the carb bowel off and found it clean and containing gas. Decided to switched to NGK BPK6ES plugs before starting to throw money and time on other potential problem areas and that cured the problem. Generator ran like a top. Hopes this helps anyone doing a search on Kohler 7.3.
 
Was the generator running flawlessly since 2011 when you last spoke of this problem? If so, that is a pretty good run on those plugs. If you have been running on the same plugs since 2011 I would like to know what brand they are. Second, if you WERE on the same type of plugs since then why would you want to change to something else? Lets see how long the NGKs last.
 
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