Thorny Kohler 6EKOD issue.

Generator ran for about 6 hours and failed because of low frequency. Low frequency happened because the engine ran rough and stalled (not a helpful or concise error statement). Mechanic diagnosed a fuel pump problem as there was power to the fuel pump, which did not run and was replaced. Same issue, new pump ran for about 5 hours and engine stoped as did the fuel pump. Again power to pump but no joy. Prior to fuel pump replacement filters were replaced. Mechanic checked old fuel pump with battery and it ran fine. Our current thought is a faulty/intermittent ground. One odd aside is that the original fuel pump produced 120 to 121 volts, new fuel pump produced 117 to 118 volts.

A bit of history: I've owned the boat for about 2 months, a 2015 Back Cove with about 250 engine hours and 22 hours on the genest when we took possession. I ran the generator under load or about 24 more hours before this difficulty started. Yes I knew a Kohler (or nearly any) marine genest would not benefit from the years of no use.

Next we're going to try a double ground to the fuel pump.

How is the pickup tube? And any lines from the tank to the pump?

Interesting perspective. I always like to look at the simple stuff first. The filter bowls for the main and gen look clean and pull from the same tank. I'd think if that was a problem we'd have some other indications. The single 480 Cumins runs fine and has had about 50 hours on it since taking possession. We'll certainly look into this, but I'm not sure at the moment exactly how.

Greg Sutton said:

Generator ran for about 6 hours and failed because of low frequency. Low frequency happened because the engine ran rough and stalled (not a helpful or concise error statement). Mechanic diagnosed a fuel pump problem as there was power to the fuel pump, which did not run and was replaced. Same issue, new pump ran for about 5 hours and engine stoped as did the fuel pump. Again power to pump but no joy. Prior to fuel pump replacement filters were replaced. Mechanic checked old fuel pump with battery and it ran fine. Our current thought is a faulty/intermittent ground. One odd aside is that the original fuel pump produced 120 to 121 volts, new fuel pump produced 117 to 118 volts.

A bit of history: I've owned the boat for about 2 months, a 2015 Back Cove with about 250 engine hours and 22 hours on the genest when we took possession. I ran the generator under load or about 24 more hours before this difficulty started. Yes I knew a Kohler (or nearly any) marine genest would not benefit from the years of no use.

Next we're going to try a double ground to the fuel pump.

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Hi Greg,

Ya gotta just LOVE the Kohler "auto-everything" operating philosophy. In other words, to start, you push a button, and the on-genset microprocessor controls everything, from fuel priming, to pre-heat, to run, to frequency control, to output voltage, to shutdown, ad nauseum. And, should the generator fail for any reason, the unit outputs an error code that is often generic, esoteric, and either poorly explained in the users manual, or simply incorrectly explained.

Is your mechanic a Kohler-trained technician, with significant experience on this fairly recent-vintage Kohler generator? Can he speak Kohler-speak? If not, you may be in for a lengthy, frustrating, and expensive troubleshooting experience chasing such phantoms as faulty grounds. For instance, given the fuel pump is digitally controlled, diagnosing a failed pump is WAY more difficult than verifying DC power at the pump.

And could you explain how "...One odd aside is that the original fuel pump produced 120 to 121 volts, new fuel pump produced 117 to 118 volts. " Fuel pumps don't produce voltage, of course. And unless and until the gen set is operating at full power, I don't believe there is voltage in excess of 12VDC running around anywhere.

I suggest you review carefully in your owner's manual (you've got one, right?) the troubleshooting section, and pay particular attention on how to obtain the appropriate error codes, and how to reset them after you've cleared the fault prior to further troubleshooting. And I further suggest you contact Kohler and/or your manual to find a Kohler-trained mechanic. These ain't easy beasts to tame, and in my opinion, WAY too complicated for the application. I'm obviously not a fan.

Regards,

Pete

Just a thought - overheat safety auto shut off switch can take effect after not too long running the gen set. Sometimes the impeller is still good enough to cool enough for a while until the engine slowely but surely gets just to the heat-point of auto shutdown. You put in new impeller since purchase? Depending on materials used... impeller flukes can weaken after lack of use. Good Luck!!

Greg Sutton said:

Generator ran for about 6 hours and failed because of low frequency. Low frequency happened because the engine ran rough and stalled (not a helpful or concise error statement). Mechanic diagnosed a fuel pump problem as there was power to the fuel pump, which did not run and was replaced. Same issue, new pump ran for about 5 hours and engine stoped as did the fuel pump. Again power to pump but no joy. Prior to fuel pump replacement filters were replaced. Mechanic checked old fuel pump with battery and it ran fine. Our current thought is a faulty/intermittent ground. One odd aside is that the original fuel pump produced 120 to 121 volts, new fuel pump produced 117 to 118 volts.

A bit of history: I've owned the boat for about 2 months, a 2015 Back Cove with about 250 engine hours and 22 hours on the genest when we took possession. I ran the generator under load or about 24 more hours before this difficulty started. Yes I knew a Kohler (or nearly any) marine genest would not benefit from the years of no use.

Next we're going to try a double ground to the fuel pump.

Click to expand...

Not sure if the terminology is yours or the mechanic's. As mentioned in a previous post, the fuel pump is 12 volts DC. There isn't a ground on the pump's power source, it's a negative wire. The housing is likely bonded to the boat's bonding system which may not be connected to the negative terminal of the generator. There is a ground on the 120 volt output of the generator. The fuel pump must not be tied to this!

Not sure if the terminology is yours or your mechanic's. If it's the mechanic's, I would consider finding another one. While it's bad for a professional to not know the correct terminology, it's worse to think he doesn't know where he's planning to run that second wire.

Ted

Make sure you test the fuel pump in the dc range on your meter . Its not 120 v. its 12vdc
Check the safety shutoffs. something is shutting it down and you are seeing the power cut off to the run solenoid or dc fuel pump is the result. Most genets have a dc breaker to protect the dc run circuit. They can trip after running a while with a poor or corroded connection. Most gensets have temp, oil, and exhaust temp shutdown sensors witch kill the power to the run circuit; resulting in no power at fuel pump/ solenoid.

Gentlemen.

I know nothing about a Kohler 6EKOD and even less about Greg Sutton, but I think Greg likely knows that fuel pumps don't produce any voltage whatsoever.

One would conclude that what was meant was that when the generator was operating with the original fuel pump, the generator produced 120V. With the new fuel pump installed the generator produced only 118V. Nice to know, but not relevant or useful in determining the problem.

What I find odd is that if as Greg said there was power to the original fuel pump and the pump did not run, but if you applied power from a battery to the pump it did run. This may indicate a bad negative, a bad 12 V+ supply or an overheat shutdown of the fuel pump itself? I have never seen a fuel pump that shuts itself off in an overheat situation but if this generator is truly computer controlled, the possibilities are almost endless.

Greg, Good luck.

My NL gen ran fine for hours. Next day it would not start, no flashing code. On the NL, there 2 sensors, oil pressure and temp. Tech came out, shorted across the temp sensor, started and ran fine. Replaced the sensor, runs fine. Things fail at an inconvenient time. This time I was tied up at my home dock. Now I have sensors for the NL gen and the Cummins 380. No doubt they will never fail again, in my life time.

Good and new to me information on impellers, however I'd think I'd have seen one of the Kohler Overheat alarms before a low frequency. I know, logic and thought is a week tool when dealing with Kohler generators

Thanks, we'll consider everything however there are Kohler overheat alarms, that would probably show up before the low frequency. If logic can be applied.....

Greg Sutton said:

Good and new to me information on impellers, however I'd think I'd have seen one of the Kohler Overheat alarms before a low frequency. I know, logic and thought is a week tool when dealing with Kohler generators

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Hey... just a minute now! "... logic and thought is a week tool when dealing with Kohler generators." Heck... for our 1977 7.5 kW Gasoline Kohler gen set I've found and purchased every book on it. No trouble figuring it out; having owned it for 14 years - I should understand its crazy nuances by 2035! LOL

My imprecise terminology. As an aside the old pump ran for several hours pumping diesel out of and back into a fuel can.

Thanks bet that was decades before the "advanced" poorly documented computer control systems. I have all the current documentation, Ops Service and Parts, that is sprinkled with something like "if this doesn't help call a Kohler rep".

GS, I can tell you from experience with another EKOD that the fuel pump is a standard generic type. These pumps will run steadily if the outlet flow is open and when the flow is stopped will slow to one click every so often. So, not hearing the pump run when the engine is stopped doesn't mean it is faulty. Safety shutdown is just like you pressed stop, any rough running is from another cause, and 98% probability it is fuel. Try hooking the old pump to the gen fuel supply and a battery and pump into a bucket - plenty of flow? Another possibility, a blocked fuel return line could cause an issue. If I was still stumped I would be looking at how to get a pressure gauge in the injection pump supply line, an adapter in the filter bleed port maybe. I don't know what the spec would be, but as long as there is positive pressure under all running conditions I would think it is ok. Absent other info I'd expect 3-6 psi.

On a sidenote, these seem to have an issue with the raw water pressure switches going bad, but again, your problem is not the shutdown.

EngNate said:

GS, I can tell you from experience with another EKOD that the fuel pump is a standard generic type. These pumps will run steadily if the outlet flow is open and when the flow is stopped will slow to one click every so often. So, not hearing the pump run when the engine is stopped doesn't mean it is faulty. Safety shutdown is just like you pressed stop, any rough running is from another cause, and 98% probability it is fuel. Try hooking the old pump to the gen fuel supply and a battery and pump into a bucket - plenty of flow? Another possibility, a blocked fuel return line could cause an issue. If I was still stumped I would be looking at how to get a pressure gauge in the injection pump supply line, an adapter in the filter bleed port maybe. I don't know what the spec would be, but as long as there is positive pressure under all running conditions I would think it is ok. Absent other info I'd expect 3-6 psi.

On a sidenote, these seem to have an issue with the raw water pressure switches going bad, but again, your problem is not the shutdown.

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Thanks so much. We did test the old pump by pumping fuel in and out of a fuel container. It ran for hours. I'll look into the fuel return issue, but I only see one fuel line from the fuel tank to the gen.

You're right, I don't see fuel return on the diagram. The test with the old pump is to check for restriction in the supply right up to the unit. Is there substantially the same flow as your other tests with the pump?

I wasn't sure if I had it - PM me with your email and I will share the service manual. It has the pressure spec for the pump and describes the 'priming mode' which gives a 30 second run of the pump only for bleeding and test.

EngNate said:

You're right, I don't see fuel return on the diagram. The test with the old pump is to check for restriction in the supply right up to the unit. Is there substantially the same flow as your other tests with the pump?

I wasn't sure if I had it - PM me with your email and I will share the service manual. It has the pressure spec for the pump and describes the 'priming mode' which gives a 30 second run of the pump only for bleeding and test.

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EN - You have Kohler genset in your 31' Uniflite? If so, what year, model kW?

Ha Ha, no, your next question, how the heck did I do it?.. I'm an electrical guy, customer's unit(s). I like the access around my single engine and my 80 gal of water. I normally need only about 12% of battery capacity a day at anchor. Are you thinking of what you can put on your Tolly?

EngNate said:

Ha Ha, no, your next question, how the heck did I do it?.. I'm an electrical guy, customer's unit(s). I like the access around my single engine and my 80 gal of water. I normally need only about 12% of battery capacity a day at anchor. Are you thinking of what you can put on your Tolly?

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Reason I ask is I owned 1973 31 Uni years ago. Twin 350's V drive trany. Fast puppy! Loved her!! "O" space for insert gen set.

Nother reason I ask... currently have the orig Kohler 7.5 in our 1977 Tollycraft. Couple foibles... but, still runs darn good. Gonna change impeller soon. New impeller cost right at $200. Heck of a time to locate the correct one.

Resolution, I think. Turns out the faulty - (ground is some terminology) and or + was the case. The plug on the fuel pump had become defective (loose), stoping the fuel pump. We put the original pump back and changed the plug. It's run for over 5 hours without stoping. As you'll recall the original pump worked for hours, powered by a battery recycling fuel in a can.

I'm still curious about a number of things, like why we didn't see a low RPM error in addition to the low frequency. Also, the original fuel pump that resulted in the generator putting our 120 to 121 volts is now in the 116 to 117 range. It's Kohler, why should I be surprised?

Hi first thing to check is RPM on govenor behind the plastic air intake box if she drops below 1450rpm she will shut down on low frequency or HZ below 50 HZ or 60 HZ depending on settings…… bring the rev in engine metering back to around 1520pm don’t go to high with revs otherwise she will go out on high frequency it’s a easy fix and will need adjusting the governor from time to time I’ve had mine for 3000hrs now since new and adjusted the Gov maybe 3 - 4 times

Kohler issues.

We were having similar problems with our Kohler 6EOD and our Kohler service representative replaced ADC-2100 Control Panel and the RIB Relay Board.

No more problems.

Sorry I should of said before the standard fuel pumps are useless I changed ours out to a Walbro one at about 400hrs the connectors on the original is just plain rediculous how they expect a clip like that to hold a connection I will never know besides a small Walbro Diaphragm fuel pump are good for 10,000 plus hrs good luck

I've got a specialist coming soon to work on our boat's annoying problems that I simply don't have time [nor desire] to address. One has to do with a sporadic, sudden and premature shutdown of our 1977 7.5 kW Kohler gasoline gen set. Sometimes she quits suddenly [after running perfectly for 30 to 45 minutes] and will not start again for an hour plus - and - sometime she continues running perfectly and doesn't shut herself off.

I've got every manual ever printed for that 1977 Kohler - as well as a brand new OEM impeller I'll have him install. Took another Kohler specialist shop [that will work only on diesel engines] to locate the OEM impeller... $198.00

Greg Sutton said:

Generator ran for about 6 hours and failed because of low frequency. Low frequency happened because the engine ran rough and stalled (not a helpful or concise error statement). Mechanic diagnosed a fuel pump problem as there was power to the fuel pump, which did not run and was replaced. Same issue, new pump ran for about 5 hours and engine stoped as did the fuel pump. Again power to pump but no joy. Prior to fuel pump replacement filters were replaced. Mechanic checked old fuel pump with battery and it ran fine. Our current thought is a faulty/intermittent ground. One odd aside is that the original fuel pump produced 120 to 121 volts, new fuel pump produced 117 to 118 volts.

A bit of history: I've owned the boat for about 2 months, a 2015 Back Cove with about 250 engine hours and 22 hours on the genest when we took possession. I ran the generator under load or about 24 more hours before this difficulty started. Yes I knew a Kohler (or nearly any) marine genest would not benefit from the years of no use.

Next we're going to try a double ground to the fuel pump.

Click to expand...

I am NOT a Kohler guy so take all this with a grain of salt, but some of the electronic control systems use ground side switching. Meaning that there is full time power to the device (fuel pump) and when demand is called for the CPU grounds the device and thusly it operates. You may have a pressure issue that the CPU is seeing and therefore NOT grounding the unit to run. Just a thought to investigate. Wiring diagrams and/or conversation with an authorized dealer might shed some light on the issue. Best of luck.