Generator Sputtering Under Load


afratki

afratki

Member
I just bought a 2005 370 SS with a 7.3KW gas Kohler generator. The gen runs fine with light or no load but within a minute of turning on the A/C it starts sputtering, popping through the intake, and losing RPM until the A/C kicks off (because of low voltage) at which point it recovers until I turn on the A/C again. Seems to me the engine is being starved for fuel. The drive engines run fine (496 HO's) so I believe the fuel quality is OK. Is There a separate fuel filter for the gen or does it take it's fuel through the same filter as the drive engines? Any thoughts on what else could be the problem?
 
I would start with changing the plugs. I had the exact same problem and my plugs were only 2 years old with very little use. I was told Kohler gennys go through plugs like crazy. Change them even if they look fine. I did and have had no issue since.
 
Since there seems to be a lot of problems with plugs on these engines has anyone experimented with different brands to see if it makes any difference? I ordered the factory NGK's.
 
I received the spark plugs (and fuel filter) yesterday, they were in Kohler packaging but are Champion plugs. I'm not a big fan of this brand but I'll put them for now.
 
Lots of folks bad mouth champion plugs but I never had an issue. Changed a set out two years ago which had been in my 95 Rinker since new, they looked fine. New AC plugs hasn't changed anything.

My Honda motor in my zero turn had Denzo plugs, and they were misfiring after two years of use. Replaced with champion plugs because no one had Denso, well that was about 10 years and there still running
 
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I've never had a problem with them fouling or misfiring, my problem was removing them. Most companies machine the threads on the plugs, Champion (or least they used to) stamp the threads. This led to a less than perfect tread seal and gave a place for carbon and other combustion byproducts to accumulate in the threads which made them hard to remove.
 
Overall, the Koehler is one of the best gennys around and pretty simple. Have had a few over the years, 7.4 and 5 and they have worked great, rarely failing.

If it's not running well, I could argue to get a genny expert to get it going, but plugs, filters, impellers, strainers and annods are easy to change/clean. Most (maybe all?) are carbureated, and can get old fuel that can mess them up. Carb cleaner works well, or just buy a new Carb (don't OH the old one, ain't worth it).

One of the biggest issues of genny's is that they are just not run. I could argue to run them a bit weekly, just like the motors.

If you're in mucky water, clean the strainer daily. Always have a spare impeller, and it's dirt simple to change. Also, have that little sleeve that goes with it (PN 359448 for the 5kw and probably same for the 7.4)
 
Pull yellow dipstick at crankcase base. Smell like fuel? If so may have washed out cyl. Usually forward plug. I use BPR6ES. A little hotter toensure burning of fuel. It is rec. to run under load for 15-20 min weekly (if poss) to keep everything "clean". Fuel needle, aft side of carb just below it, is spring loaded. Remove single wire then remove needle/plunger and check movement. should be "free". If needle is difficult/feels like binding, replace needle. $90 or so on net. If forward plug is black heavy fouling, may not be "hot" enough. Just a couple of penny thoughts....
 
Update: My issue with the generator is fixed. I replaced the both fuel filters, the spin on one mounted on the port side and the smaller one on the generator (this one was still painted white so I assume was original. I contemplated whether this ever needs replaced because the fuel is already filtered by the spin on one before it gets there but it was easy enough to replace so I did). I also replaced both spark plugs that looked like they had been in there a while.

Here's the caveat, when I posted the problem we had just purchased the boat and taking her on the maiden voyage. The following weekend we had her in a slip on shore power and I flipped on the AC and quickly threw a HPF code because of no water flow. I bled the sea strainer and quickly resolved that problem. I don't know if this could cause an excessive load on the gen and make it sputter but I had already replaced the parts on the gen before this and so I'll never really know which was causing the problem but it's fixed and the wife is cool and most importantly happy!

gixr04 said:
Pull yellow dipstick at crankcase base. Smell like fuel? If so may have washed out cyl. Usually forward plug. I use BPR6ES. A little hotter to ensure burning of fuel. It is rec. to run under load for 15-20 min weekly (if poss) to keep everything "clean". Fuel needle, aft side of carb just below it, is spring loaded. Remove single wire then remove needle/plunger and check movement. should be "free". If needle is difficult/feels like binding, replace needle. $90 or so on net. If forward plug is black heavy fouling, may not be "hot" enough. Just a couple of penny thoughts....
Click to expand...

Interestingly enough the front plug was black but I had already installed the parts before you posted. I try the hotter plug next time.
 
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