Foretravel Owners' Forum For owners and Fans of Foretravel Motorcoaches September 10, 2025 ...

Generator won't stay running

July 18, 2021, 07:09:51 pm

One of the things I asked MOT to do was figure out why the generator won't power at least the front a/c while we're going down the road. It quite happily powers the refrigerator and computer, but not an a/c. However, when we were trying to figure out what the alternator's problem was Monday, the generator powered not only the refrigerator but also both a/c units for nearly eight hours without a hiccup. When we finally left Tuesday I figured that the problem was solved. Not so. A couple of hours down the road the generator quit. Turned off the a/c units and all was fine.

What's the difference between sitting still and going down the road? My first thought is that the generator thinks it is overheating, but then why wouldn't that show up while in the parking lot?

My second thought is that while we were working on the alternator the Detroit wasn't using much fuel. Even when we were "leaving" we didn't go very far, and the fuel tank wasn't full because I thought they might have to remove it to do the bulkheads. Perhaps the tank vent was clogged. If that was true, though, I would think that the Detroit would notice a reduced fuel flow first.

Most, if not all, of the old insulation in the generator compartment is gone, and I can see the outside from in the generator compartment, so I'm pretty sure there is plenty of air coming in.

So, what next? Fuel filter? Air filter? Again, though, why only while going down the road and not sitting on an asphalt parking lot in East Texas in July?

Quote Selected

Re: Generator won't stay running

Reply #1 – July 18, 2021, 07:35:26 pm

You need to check the oil  sending unit. If it is failing it could be causing the shut down.

Mike

Quote Selected

Re: Generator won't stay running

Reply #2 – July 19, 2021, 08:13:43 am

Vibrations.  I would check all of the wire connections for the generator especially for the sensors.  Look closely at each crimped terminal, I've had some where the terminal just pulled off> bad crimp.
When I first got my '99 I had a similar problem with the generator where it would just shut off with no indication why.  I found out why when I moved the control board and relays out from on top of the generator to the side compartment.  There was a wire that was broken in the bundle.  Just sitting it would run fine but when driving it would lose connection.  This was the wire to shut down the generator.  MOT worked on it before we left for home when we bought it but couldn't find the bad wire.  FOT also worked on it and didn't find the wire.  If I or the mechanics would have moved the bundle of wires while it was running it would have shut down.

Quote Selected

Re: Generator won't stay running

Reply #3 – July 19, 2021, 08:58:15 am

We used to install an air deflector on coaches like yours because the air flow when traveling would not let the fan push the air through the radiator.

Quote Selected

Re: Generator won't stay running

Reply #4 – July 19, 2021, 12:21:33 pm

I have had the same symptoms twice.  Both times a small black wire was broken at the crimp to the connector not allowing the genset to know it was producing electricity resulting in the genset being automatically shutdown.  Wire is in the control box.  Just pull the cover and it is easily seen.

Nick

Quote Selected

Re: Generator won't stay running

Reply #5 – July 19, 2021, 08:53:05 pm

I think Forest and Ron are onto the problem, as their explanations seem to match the symptoms of the engine shutting down while under load on the highway. After it gets a bit darker I'm going to shine a light from the generator compartment forward. There is a grill back there that I think lets air into the generator compartment. When light was right, I could see stuff in the nose area. I'll see what I can see with a bright light about sunset.

Ron, what is that deflector like? Is it a plate set several inches forward of that grill?

Quote Selected

Re: Generator won't stay running

Reply #6 – July 20, 2021, 01:58:44 pm

It was a fiberglass scoop affair that was mounted under where the air discharge is so it would act sort of like a vacuum to help the air flow without the air being forced against the fan. I hope that helps. James Triana should remember. I don't know if they have any drawings of it. It may have been called a diffuser but don't know. I am not an artist so I can't draw what it looks like.

Quote Selected

Re: Generator won't stay running

Reply #7 – July 20, 2021, 05:47:20 pm

Thanks. Yes, I have one and it is clear of debris.

Quote Selected

Re: Generator won't stay running

Reply #8 – July 20, 2021, 09:37:40 pm

Ok how about your belt tension

Quote Selected

Re: Generator won't stay running

Reply #9 – July 21, 2021, 08:40:18 pm

I would think MOT would have checked that. The fact that it powered both air conditioners for eight hours without a hiccup while on MOT's parking lot, but quits under load while going down the road, tells me that something changes while underway.

I've pulled over and opened the bay door as quickly as I could when it has quit and aimed my IR gun at everything I could. No clouds of smoke when I opened the door, nothing seemed abnormally hot, the fan runs when the engine runs, oil and coolant levels are just fine.

You don't suppose it is getting old and cranky, do you?

Quote Selected

Re: Generator won't stay running

Reply #10 – July 23, 2021, 07:13:32 am

Fought the exact same thing for two years.
Finally figured it out. I can call you tonight if you prefer to discuss.
Here is the thread from a year ago.

PowerTech Generator confusion

Quote Selected

Re: Generator won't stay running

Reply #11 – July 23, 2021, 08:56:46 am

How much fuel did you have in tank when it shut down? 
Were you going up hill or down when it died?
If you did try to restart were you driving or stopped?
Did it restart right away or take some cranking?
Is your auto start (just press the button for a second and it goes into start sequence) or do you have to hold down start button until it starts?
Do you have a preheat switch?
If you have a preheat switch did  you press before you tried to restart after shutdown?

Quote Selected

Re: Generator won't stay running

Reply #12 – July 24, 2021, 06:09:29 pm

Tank is filled at each overnight, and we generally travel less than 250 miles per day, so tank is always at least 3/4 full.
Doesn't seem to matter whether going up hill, down hill, or level.
Restarts within a few minutes. I don't always notice it shutting down, unless the a/c is on.
No autostart. I hold the start/stop switch until it is running.
Preheat switch used at first, but not later. Fires right up when 80 or above.

Justin's link may be the solution.

Quote Selected

Re: Generator won't stay running

Reply #13 – July 24, 2021, 07:47:02 pm

Have you checked the voltage at the fuel shut-off solenoid?  Possibly a ground problem?

Quote Selected

Re: Generator won't stay running

Reply #14 – July 24, 2021, 08:28:25 pm

The supply hose to the identical generator to yours was letting air in on our coach. Since we have the same year U300 and the same generator, it may be time to change your supply hose. It can be done in 30 minutes if you prepare for it. Bend it over with strong glasses on and if you see tiny cracks, that's the problem. Also, if any part of the supply line is damp.

Check the tension on the fan belt. It drives the water pump and the fan.

If you have the T valve on the steel line, open it part way when under load. It allows the air to go back to the tank.

Do the gallon external diesel supply test if in doubt.

Pierce

Quote Selected

Re: Generator won't stay running

Reply #15 – July 24, 2021, 08:54:59 pm

What's the difference between sitting still and going down the road?

Air Flow......... if your talking about a GrandVilla. I learned this the hard way. Not sure why, but I installed a remote temperature gauge on the gen set and could watch the temp go up while traveling and drop back down when stopped. This was with the clogged radiator, not as noticeable now after having the local radiator shop clean and flush, it looks and works like a new one.

Quote Selected

Re: Generator won't stay running

Reply #16 – July 24, 2021, 09:38:58 pm

Pierce, are you talking about the fuel line for the generator? I had all of the fuel lines replaced a few years ago. Could be that, but I'm leaning more towards Justin's solution. I just talked with him, and I think the next step is to see if I can remove the radiator without destroying anything.

Quote Selected

Re: Generator won't stay running

Reply #17 – July 24, 2021, 10:09:27 pm

David,

I just did that a few months ago and used a HD Prestone cleaner on it refilling with a 50/50 mix of antifreeze for Asian vehicles and distilled water. I replace the belts and a couple of the hoses also. I have a temp gauge and fuel pressure gauge that really comes in handy. I've never had a heating problem because of a clogged radiator but I wish I had a dash temp gauge. But to be honest, the generator always runs cool except for the time the bottom hose by the crankshaft failed.

Removing the radiator only takes about 15 minutes. First, you have to pull the generator out and lock it there. If I remember correctly, you need 14mm and 11mm wrenches. I'm sure I'm forgetting more but nothing special. The fan might have been 10mm. Look at my post from a few months ago. I used the generator for house power quite a few times with the outages so wanted it to be perfect for this summer plus our normal winter blackouts too. See my old post for the correct belt also.

Some good advice from the other members above. Hope you get it sorted soon.

Pierce

Quote Selected

Re: Generator won't stay running

Reply #18 – July 24, 2021, 10:27:15 pm

David,

Post with annotated photos, part numbers: 10K PowerTech Maintenance & Modification

Pierce

Quote Selected