[Gnawrocki1]

Before I take more involved actions, I wanted to make sure that I have taken the right troubleshooting order.

Normally I start the generator, engine, and aqua hot monthly and warm up a bit even though for much of the year we start at 100F and go up from there in Phoenix.

I have never had an issue with the generator starting and it always fired right up.  This generator has seen moderate use prior to me purchasing and has about 1500hrs on it.  I have not really used it much, and now even much less now that I have 2400W of Solar on the roof.

But this month, the generator does not start.  It cranks fairly well from what I can tell, and the batteries have enough juice to start the main engine. I have the generator hooked up to the engine start batteries since the 48V lithium house batteries have been installed.  I have had it that way for over 2 years now, and it never presented any problems.  

The generator is the 20KW Kohler, 1998 coach 500.

Here are some of the things I have checked so far:

1. Initially tried to bleed/prime the fuel system on top of the fuel filter.  However I found out that the prime switch electrical connections to the fuel pump were intermittently connected at the "snap on" wire splice (I always hated those).  That that is right before the fuel pump electrical connection.  I have removed the splice and soldered in new wires.  The prime function now works and I could bleed the system consistently.  I am not going to say the pressure in the system was high, but fuel did flow with the screw backed out about 1 turn. No air came out, only fuel.  This did nothing for my start problem.
   
2. I changed the fuel filter and the air filter.  I did not change the water separator filter, the viewing bowl seemed clean and I did not have a spare.  All fuel I have seen looks good and has no odd smell, even though it is 9 months old.  The tank is full.   After changing the fuel filter, I bled/primed the system at the filter housing screw on top until no bubbles appeared.  I am guessing I pumped out 2-3 oz out of the bleeder screw.  The air filter was dirty, but not horrible.  Again, engine turned over, but did not fire at all.  I cranked longer than usual, just in case there was some air trapped above the filter.
   
3. I took a short cut to verify that the all of the safety systems were not activated  (overtemp, oil pressure, fire extinguisher) by hooking my volt meter up to the fuel pump electrical connection.  When I crank the generator, the fuel pump does get power.  With cranking noise I cannot tell if pump is on, but I imagine that it is since it has power.   Again crank but no start.
   
4. The voltage to the fuel pump during cranking was about 9.8V.  Maybe that is expected while cranking but it did feel lower than I had imagined
   
5. The fuse to the fuel pump is good as checked with continuity
   
6. Radiator is full
   

My current thought was to replace the fuel pump, but wanted to ask the crew if I missed any obvious troubleshooting steps.  Possibly I could hook up a fuel pressure gauge to verify pressure, but I am uncertain if the pressure at the bleed screw is what is delivered to the injectors as it may be on a line back to the tank???

Thanks for reading the entire post!

[Wanderman]

If you have a fire extinguisher/suppression system if it's low or empty it will cause the generator not to start. There is a bypass you can do until you can get it filled.

Do a search here for details.

You should have at least the year of your coach in your signature, it would be very helpful for diagnosing issues and offering solutions.

[Gnawrocki1]

If the fire extinguisher system is making it not start, would the fuel pump go on during cranking? I did have fuel pump voltage during cranking.

It does not seem to fire during cranking.

[HoosierDaddy]

Did you check to make sure the fuel shut-off solenoid is activating?

[Richard]

What Dean said.

Manually hold the fuel solenoid open while cranking, 9.7 volts may not be enough to pull it open fully. You can take it apart and clean the slug inside the coil. They get gunked up.

Second change the fuel filters.

[Gnawrocki1]

The fuel solenoid is not activating.  I have heard of there being a solenoid but never understood how they were supposed to work.  

When I manually move it, it slides very easily and it starts right up.  When I release it unactivates and generator stops.  

So at least I have found the issue with your help, now to  troubleshoot that buried system.  

If the fuel pump is getting voltage while I crank, does that tell me that the fire extinguisher, low oil pressure and over temp circuits are not faulting to deactivate fuel shut off solenoid?  It would cut down the troubleshooting significantly.

[BusNit]

Glen, I had a similar issue with mine. It has something to do with the relays in the control box that latch the fuel solenoid. One of my relays was burned up along with a diode. I replaced both with NOS parts on eBay. Worked for a bit but gave me the same issue. My solution was to bypass all that and instead ran a Hotwire with a switch to the fuel rack solenoid. Generator gauges work so I monitor them. With the way I did it, if the coolant were to leak or have low oil the generator would keep running until it seized up. I do not have anyone who can work on these so this was my remedy. It has been working for me perfectly and reliably for the last couple of years.

[Richard]

Glenn I would not assume anything about the safety circuits based on fuel pump voltage. It will two days before I get back to the coach and yanmar manual.

[HoosierDaddy]

The fuel solenoid is not activating.  I have heard of there being a solenoid but never understood how they were supposed to work.  

When I manually move it, it slides very easily and it starts right up.  When I release it unactivates and generator stops.  

So at least I have found the issue with your help, now to  troubleshoot that buried system.  

If the fuel pump is getting voltage while I crank, does that tell me that the fire extinguisher, low oil pressure and over temp circuits are not faulting to deactivate fuel shut off solenoid?  It would cut down the troubleshooting significantly.

Here is my shade-tree mechanic understanding ... There are two windings in the fuel solenoid. A high current pull-in winding that ignores the safety and oil pressure/temp inputs and a second winding that holds the rod in place as long as safety circuit is not activated allowing fuel to flow to the injection pump. On my Yanmar there are two of those "ice cube" solenoids that control the current to the Fuel solenoid. They are located on the side of the engine just below the fuel solenoid near the manual start switches on the flywheel housing. They are cheap and easy to replace.

[Gnawrocki1]

Well, I started the troubleshooting by removing the fuel stop solenoid to give it a test. I think I read on some other posts that the start function on a 3 wire solenoids that during starting the safety (low oil, high temp, and fire extinguisher) were triggered the generator would start, but them immediately turn off.   This however was not correct, at least for my system.  The systems on this coach seem all as they were from the factory on everything I have checked so far, this was no exception.

As all of the connectors were crimped, I ended up cutting them out and putting Anderson powerpole connectors on all three leads so I could bench test.  It was very tight in there and the wiring was short and not crimped very well.  I could not get in there with a crimper, so I had to solder the connectors to the wires.  So now if I have to go back in there at some point in the future I can without having to cut off connectors.

I tested out the white (start +)  to black (ground) leads by connecting to a battery.  The solenoid was fine, so it went back in. It must not have been getting power during the start sequence.   All operations of the solenoid were very smooth and I did not add any lubricant, or clean it out because it felt so good.

The next test was the Fire Extinguisher circuit as recommended in my post by several Guru's as a likely issue.  I could barely reach the connector with one hand and was just able to unplug it.   I put an alligator clip between the contacts, and the generator sprung to life just as some of you mentioned.  Thanks for the hints!

I removed the fire extinguisher and it felt empty.  There was no continuity between the two leads coming out of the fire extinguisher.  Is there a place to get these refilled, or should the system just be updated?  I can only imagine there are better ones now on the market. The fire extinguisher that was in the coach has a last inspection of 1997 dated on it, so it is all original...... 

Thanks for all your replies, they were very helpful!