Kohler Generator 4CCO starts but won't run

[Capt Jack]

I have been working thru the issues list on my new to me 1984 Fu Hwa Europa trawler. It has a Kohler 4CCO generator that I replaced the fuel solenoid on and it ran for about 20 minutes and shut off. When I try to restart it pulls the solenoid in like it will start (and I have 12 volts to the solenoid) but as soon as the engine fires the solenoid shuts off and the DC breaker trips. If I hold the solenoid on the engine will run and the DC breaker does not trip, but I have no voltage at the fuel solenoid.

I am puzzled and asking the experts here for help. Any ideas?

Many thanks
John

 

[Phil Fill]

After the engine cool down does it start and run? If so install a fan in the control box to keep cool. Our gen set would shut down if to warm, and would not start until cooled. I installed a separate dc switch direct to the solenoid so it would not shut down if to warm.

 

[LarryM]

John,

In order for the 4CCO to continue to run after it fires and you release the start switch, several things must happen to keep the fuel shut-off solenoid energized.

Obviously, all of the wiring must be intact and connected. Double check this, particularly after any service. I just had this happen to me last week and it turned out to be a broken wire on the LOP switch. It was accidentally broken when we replaced the starting battery right next to it. On examination, it was corroded in the crimped connector and was only hanging by a couple of strands. These are old generators.



The safety shutdown sensors must all be open. They are:

• Low oil pressure switch
• High water temperature switch
• High exhaust elbow temperature sensor
• High cylinder head temperature sensor

Further, the generator must produce AC voltage

There are circuit breakers, diodes, relays and a control board in play.

Attached is the basic troubleshooting chart from the Kohler service manual and a wiring diagram to help you with your repair.

Good luck

 

[kulas44]

I generally just pull all of that old $hit out and throw it away. Replace it with a new engine controll system that actually can tell you why it shutdown, and at the same time I install a new PowerTronics ac voltage controll system. Its just not worth my time screwin around with that old setup. They are great generators and can run forever but the old control system is a PITA.

 

[Capt Jack]

After the engine cool down does it start and run? If so install a fan in the control box to keep cool. Our gen set would shut down if to warm, and would not start until cooled. I installed a separate dc switch direct to the solenoid so it would not shut down if to warm.

Does not matter hot or cold - same thing

John

 

[Capt Jack]

Attached is the basic troubleshooting chart from the Kohler service manual and a wiring diagram to help you with your repair.

Good luck [/QUOTE]

Thanks - I will be back to the boat this weekend and will track the circuits

John

 

[Capt Jack]

I generally just pull all of that old $hit out and throw it away. Replace it with a new engine controll system that actually can tell you why it shutdown, and at the same time I install a new PowerTronics ac voltage controll system. Its just not worth my time screwin around with that old setup. They are great generators and can run forever but the old control system is a PITA.

Sounds like an interesting idea, but also sounds like it could take some serious boat bucks. Do you have sources for the parts you would be willing to share and an idea of what it takes to do this?

Thanks

John

 

[kulas44]

Not as expensive as you may think. I'll get back to you after checking $

 

[kulas44]

I've used several different engine control units. The ECU-9988 N is good. 2 on ebay at $300 and $225. I prefer and reccomend PowerTronics acv regulators. My favorite is the XR500B-400, but its kinda spendy at $760 and not really neccessary for this application. The XR8 at $396 will do everything you need. You may be able to use the VP4, its only $178.50. IIRC your gen is a brush type, if so you will need the SEM250A static exciter module, possibly. I have operated this type gen without one. So, your cost could be from $400 to $1300.

 

[Capt Jack]

I've used several different engine control units. The ECU-9988 N is good. 2 on ebay at $300 and $225. I prefer and reccomend PowerTronics acv regulators. My favorite is the XR500B-400, but its kinda spendy at $760 and not really neccessary for this application. The XR8 at $396 will do everything you need. You may be able to use the VP4, its only $178.50. IIRC your gen is a brush type, if so you will need the SEM250A static exciter module, possibly. I have operated this type gen without one. So, your cost could be from $400 to $1300.

Great info - thank you!

 

[motion30]

I have a lead with alligator clips on both sides and I start jumping the sensors one at a time. That is a classic conditions of a bad sensor. Or bad conection

 

[bilge53]

I had that same problem. Turned out being a tandem connection (2 into 1) in the control box. Found it by wiggling wires and bingo...one was loose in my hand. Hope it is that simple.

 

[rwidman]

I have a lead with alligator clips on both sides and I start jumping the sensors one at a time. That is a classic conditions of a bad sensor. Or bad conection

Or an actual fault that the sensor is sensing.


Is anyone missing the point that the control panel is designed to shut the genset down if there is a fault to avoid further damage?

 

[High Wire]

The DC circuit breaker should not ever trip unless there is a short to ground somewhere or the breaker is defective. A DC clamp on ammeter with a peak hold feature will show the current going through the breaker to show if its good or faulty.

 

[bilge53]

The DC breaker on mine would blow in an over crank situation.

 

[Capt Jack]

Update

Tonight I blocked the fuel solenoid and ran the generator. I have 120 volts out and can run the A/C on the boat so it is producing a decent output of 120 power. I still have no voltage to the fuel solenoid except in the start cycle. I checked the wires around the controller board and all appear to be solid and connected properly with no signs of corrosion or damage (it doesn't look like any of them have had the smoke let out of them either ).

Ideas?

Thanks for the help!

John

 

[kulas44]

Zakly. The safety system just shuts down the gen. No way to know why. Pitch all that $hit. At least a light telling you why it shutdown would be nice.Great gen,,, poor system.

 

[LarryM]

Tonight I blocked the fuel solenoid and ran the generator. I have 120 volts out and can run the A/C on the boat so it is producing a decent output of 120 power. I still have no voltage to the fuel solenoid except in the start cycle. I checked the wires around the controller board and all appear to be solid and connected properly with no signs of corrosion or damage (it doesn't look like any of them have had the smoke let out of them either ).

Ideas?

Thanks for the help!

John

Just to recap the process, on the Kohler 4CCO and many other similar generators, when the start switch is pressed, a number of things happen, 4 of which are:
1. The starter solenoid is energized to engage the starter
2. The fuel shut-off solenoid valve is energized in the 'run' position
3. The engine safety shutdown circuit is bypassed
4. The generator windings are energized so that it can produce AC power
Most of this is a function of the controller board.

Once the engine begins to run and the generator produces 120VAC:
1. The starter solenoid is disengaged, even if the starter switch is still being depressed
2. The engine safety shutdown circuit is energized which now provides
power to the fuel shut-off solenoid valve and maintains it in the 'run' position

If while running, any of the 4 sensors close (become grounded), the safety shutdown will interrupt power to the fuel shut-off solenoid valve and stop the engine. Further, if the generator stops producing 120VAC, it will also trigger a shutdown. Again, the controller board, two external relays, a diode, a fuse and a circuit breaker control these functions.

When stopped, the 3 temp sensors sensors are 'NO (normally open)' and the OP switch is 'NC (normally closed)'. These can easily be checked with an ohmmeter. To check them, you must remove the corresponding sensor wire because they are all wired in common. The engine should be at or below operating temperature for the test.

If those simple tests don't reveal the problem, the troubleshooting section in the Kohler 4CCO Service Manual should help. If you need one, PM me and I will send you a PDF.

If it turns out to be the controller board, Flight Systems, Inc. can quickly rebuild it for a nominal price.

If I had known about the mods Kulas44 mentioned, and had the ability to install them, I surely would have 'pulled all of that old $hit out' and used more modern components to rebuild my 4CCO last year.

As it turns out, I completely replaced the wiring, relays, diode, breaker and the control board with original components. It runs great now . . . . I hope for a good while.

 

[Capt Jack]

Just to recap the process, on the Kohler 4CCO and many other similar generators, when the start switch is pressed, a number of things happen, 4 of which are:
1. The starter solenoid is energized to engage the starter
2. The fuel shut-off solenoid valve is energized in the 'run' position
3. The engine safety shutdown circuit is bypassed
4. The generator windings are energized so that it can produce AC power
Most of this is a function of the controller board.

Once the engine begins to run and the generator produces 120VAC:
1. The starter solenoid is disengaged, even if the starter switch is still being depressed
2. The engine safety shutdown circuit is energized which now provides
power to the fuel shut-off solenoid valve and maintains it in the 'run' position

If while running, any of the 4 sensors close (become grounded), the safety shutdown will interrupt power to the fuel shut-off solenoid valve and stop the engine. Further, if the generator stops producing 120VAC, it will also trigger a shutdown. Again, the controller board, two external relays, a diode, a fuse and a circuit breaker control these functions.

When stopped, the 3 temp sensors sensors are 'NO (normally open)' and the OP switch is 'NC (normally closed)'. These can easily be checked with ah ohmmeter. To check them, you must remove the corresponding sensor wire because they are all wired in common. The engine should be at or below operating temperature for the test.

If those simple tests don't reveal the problem, the troubleshooting section in the Kohler 4CCO Service Manual should help. If you need one, PM me and I will send you a PDF.

If it turns out to be the controller board, Flight Systems, Inc. can quickly rebuild it for a nominal price.

If I had known about the mods Kulas44 mentioned, and had the ability to install them, I surely would have 'pulled all of that old $hit' out and used more modern components to rebuild my 4CCO last year.

As it turns out, I completely replaced the wiring, relays, diode, breaker and the control board with original components. It runs great now . . . . I hope for a good while.

Great info - thank you! PM sent

 

[High Wire]

Also there is a 10 amp FUSE. Check that.