Onan Generators IMHO

[HornedToad]

I’ve been following a generator thread on the forum with great interest in the conclusion. I don’t want to hijack so I’m going to start a new thread.


I am puzzled by the many post on the forum about issues with the Onan generators. I’ve been tailgating since 2008, with a group that has grown to about a dozen guys/gals, most of which have toy haulers with an Onan, and as we share camping stories I can’t recall anyone mentioning any problems with their generators.


I’m on my second Onan, I put well over 500 hours on the first in 15 months and I’m just over 500 hours on my Voltage after 16 months… without fail. It’s hot in West Texas and you gotta have AC, even in the Fall, so out tailgating you fire up your generator when you pull in the lot Friday evening and run it until you head home Sunday afternoon. (Tech just added power poles to some of the tailgate spots last year) Most of my tailgate buddies also have boats and our local lake only has dry camping, so during the Spring and Summer at the lake you fire up the generator when you set up Friday and it runs until you pack up on Sunday.


A post in the thread mention above… “I am sitting at 30ish hours on my generator so far” made me realize that maybe it is a use it or lose it proposition.


I’m going to pick on Cale, cuz I like him. I don’t think he has had any problems with his generator so far, but if he has only run it 30 hours in the ten months, that’s just over the break in period, he should still have the gas in the tank from when he filled up last year.


I read a recommendation that you should exercise an Onan generator every 30 days when idle and run it for two hours to bring in up to max operating temperature. That’s at least 24 hours a year.


Seems like everyone I know that runs their Onans several hundred hours a year has had good experience. Are the issues with an Onan from just trying to fire it up every blue moon???

[DesertRat]

Only problem I've had with mine is at a low load my idle rpm doesn't stay steady. Once a hi load is placed on it it's fine. Now if it was the old style carb unit I could just adjust it. No way I know of on the new ones. Not saying this is a Onan thing as the 2400w Yamaha I had did the same thing.

[donzinger]

Another reason I got the AGS Kit with my Magnum Inverter - in addition to starting it up when the batteries reach a set low-point, it will start her up after 30 days of non-use and run two hours and shut down...

[eightydo]

My Gosh I thought the Generator was for just looking at, and showing your friends I did not think it actually operated.

[calewjohnson]

Mike,

Thanks! I put about 300 hours on my last Onan, all trouble free hours. While the last one was my first genset, I started and loaded it once a month, just to ensure the stators/windings stayed dry, I did not want corrosion to form on the electrical producing parts (being in the Navy, we are always in coastal towns)...


This one so far gets ran a couple hours a month, I have also done my due diligence and only put a few gallons at a time in the tank, so it is not just sitting. I have held off on doing the break in maintenance, so as to marry it up with our long trip, I think we will put 150 hours or so on it in the next 30 days or so. This will keep me from having to do an oil change while on the road. With the impending heavy use and the few problems in the said generator post, I am doing some preventative maintenance and gathering parts for the road.

Cale

[HornedToad]

Thank you Cale for not taking offense to quoting you in my post. I didn't mean to offend anyone that has posted about their generator.

I don't think it matters if you run your generator 50 hours a month or just exercise it the recommended two hours. As 80's sarcastic humor points out, if you just look at it for months on end, when you do need it, will it operate?

[wahoonc]

I have had a variety of generators over the years. I have a Honda EX series construction generator that has well over 3,000 hours on it. The engine is starting to show signs of needing replacement. I have had several Onan generators, most had 1,000+ hours on them with minimal issues. I do think the two most important things are proper break-in and proper exercise. I also start my generator no load and let it come up to speed and settle in for 10 minutes prior to loading it up, I do the same thing in reverse when I shut it down, cut the load and let it idle down for 10 minutes. FWIW I have never had to replace the generator portion of any of my good generators, I have replaced an engine here and there over the years, but those were used units that I did not know the full history of.

Aaron

[jeffwelsh]

My generator has quit from day one. I have tried to do the 2 hour exercise, but it usually doesn't run that long. I have 27 hours on mine, since Oct. 2014 when I took delivery. I filled up with premium gas while out on a trip and just put a can of sea foam in last night. We are heading out this weekend, so I'm going to run it some since we only have 30 amp hookup in Houston Woods.
-Jeff

[Pirate]

I suspect the problems I've been having keeping it running in hot weather is a problem with the fuel delivery system more than a Generator problem.

The "fuel hose" looks incredibly cheap and probably getting sucked closed when its really hot...the hose that is!

With the new second pump pushing fuel forward...that seems to keep the hose full of fuel, and thus can't be sucked closed.

Running great now. Will know for sure in a week as we head out on a month long trip...some of which will be boondocking!!!

Pirate

[HornedToad]

Pirate,

I picked up on the fuel hose issue from your other thread. I'm familiar with these hoses from installing an Onan off eBay in my first Torque Toy Hauler. On the Heartland forum you read of very few generator issues.

The guy that bought the Torque parks next to me in storage and I'm going to try and catch up with him and do a side by side comparison of these hoses to see if there is a difference.

I hope you'll post photos and a detailed write up on your fix, as before, for everyone's benefit. If I suspect this could be a problem with my unit I'll be the first to follow your lead. Thanks.

[jeffwelsh]

The issue with the fuel hose getting sucked closed is certainly consistent with the problems I'm having. It definitely some sort of fuel starvation. Even when I had gravity working in my favor, the hose could have been sucked closed and as soon as the genny stops the pressure is off and the hose allows some fuel to flow. Starts back up and runs again till the same thing happens, usually on a quicker cycle. Like I said in another post I got a gas bath when my unit was tilted nose down, so I assumed good flow. It will be interesting if a rear pump is the long term fix.
-Jeff

[calewjohnson]

You know, I have never filled my fuel tank full, is there a chance that the vent is unable to vent when completely full?

If we do have inferior fuel lines, how hard would it be to change out the lines? Would there be any benefit to moving to a larger line?

Cale

[sundancer 87]

You could go with a larger diameter fuel line but it would be a waste of money. Simple hydraulics dictate that only so much liquid can flow through an orifice with a given size.
A larger line would provide volume but the size of the intake on the fuel pump will only pass what it can. That intake port might be 1/4" or slightly larger and the circuitry of the carb is much smaller. You would essentially have fuel backed up in the line and wouldn't really accomplish anything regarding this problem.

[Pirate]

Its a real PITA to change out the hose. Now, the OEM hose is a real PITA to push over 5/16ths brass nipples. I don't think moving up to a good quality 3/8ths inch hose would be overkill.

You can't hook a new hose to the old hose, then pull the old hose out from the back and pull the new hose in.

If you look at the Generator enclosure, looking in, on the left side, at he bottom...you will see the gas supply hose and the vent hose back to the charcoal filter.

The hoses run between the galvanized Generator enclosure and a steel partition in the frame. So its about 3" wide.

The hoses go out that hole, turn hard right go across to just past the drivers side of the galvanized Generator enclosure.

There the hoses make a hard right turn and pass through a 3" hole and go into a black

From that hole the hoses make an immediate right turn into a 2" black ABS thin wall conduit that runs all the way back to within a foot or so of the front side of the Toy fuel tank.

I wanted to run a red, hot wire, from the fuel pump at the Generator back to the new pump at the Generator fuel tank.

Finally wound up disconnecting the vent hose and the fuel hose at the Generator and pull them all the way out the end of the black ABS conduit.

Then take the red wire, bend it over at about 3" and put that hook into the fuel line. Use electrical tape to tape the two hoses and the red wire together for about 4" from the end.

Now you can push the three components up through the ABS conduit to the end, where it goes through the 3" hole. You have very little working room, but it is possible to turn the three component to the passenger side and push them about an inch at time behind the Generator.

Slowly you will get the components over to the hole where they need to come out, pass alongside the generator, reconnect to the pump.

On my Generator the hot wire to the pump has fuse holder and 7.5 amp fuse.

Using a crimp on splice, I tied the new red wire to the fused wire.

Push the switch to stop and hold it to prime and check to make sure both fuel pumps are spinning and pumping.

Switch to start...and it starts promptly and smoothly.

That was the fix. Not exactly easy, took about 5 hours...but it did solve the problem!!!

Pirate

[sundancer 87]

Would you say the OEM brass nipples on the fuel pump are 1/4" ?

[Pirate]

I recall they are 5/16 on the vent hose fitting and the fuel pump.

Pirate