Onan generator problems--

[Walkingant]

Hi,
I purchased a 1990 Airex 29foot motorhome--as-is where is, as it was a
repo and sat for over 2 years at the bank. No one wanted it because of the last owners paint "alterations".

It runs well, with 47k miles on a 454 P30. I bought it on a Friday and immediately drove it home, about 340 miles, then out to the desert for a week, ran great! I have put about 880 miles on it.

The generator --a Onan 6500. has 302 hours according to the meter.
When I try and start it from remote or the push switch on the unit it
will turn over once, maybe twice and clicks--like there isn't enough power.

Symptoms:
It only turns over when RV is running and only once or twice.
House batteries (two 6volt wired to make 12v) are weak/dead.
The generator will not make a sound if the RV is shut off.

I hooked up a jumper cable from my truck to the Onan generator,
and disconnected the fuel line and replaced it with a longer hose and put the end in a gallon gas container.

It took a few tries, but the generator started and after a few coughs, ran well. I let it run the gas nearly out. Shut it off, hooked it back up to the RV gas tank (it has over 1/2 tank) Restarted the generator, started with one touch, it ran the gas out of the carburetor and line, but would not pull any gas from the RV tank.

I am guessing that:

The house batteries are toast--will not charge up much when driving.
I have a issue with the gas line going into the tank.

The batteries replacement is an ez fix (as long as new batteries turn the generator well enough to start? --the gas line issue, anyone have any ideas?

My first thought, was, there is plenty of room under the RV, I should put in a separate generator gas tank, but read through posts and won't do that.

Thanks

[BFlinn181]

Check for a filter in the line between gas tank and generator. If you find no filter, remove hose at generator and apply air pressure through the hose to the tank. (Take gas cap off first.) Listen for bubbling in the tank. If you can't blow air through the hose, look for a kink or replace the fuel line.

["007"]

Welcome to irv2.
Your batteries if they have been sitting that long maybe toast but first try charging with a stand alone battery charger. Will take to long off engine alternator.
Check the ground cables off battery and the Gen to the chassis frame.
The Gen needs a good 12v from batteries to run.
You may have to clean old gas from carburetor walls of Gen by constant running.

[Walkingant]

hi,

I charged the batteries, both were at 100%--re-installed them into the RV,
the Onan generator only made a very faint "buzz" to let me know I was pushing the start button. Same as before.

I have cleaned what connections I can, it does still turn over once with the RV engine running, If I hook up jumper cables it starts up with an exterior gas source. (haven't had time to see if the gas line is clogged).

Any clues?

And thank you for your responses!

[PirateCamper]

I bought mine used the week before Labor Day. Brought it home and everything worked great. Next evening we were going to get it loaded for Labor Day weekend trip. Onan 4K started up sputtered and shut off. Next try I got the buzz and rattle. Cleaned every connection, charged the batteries, no good. Next day I took the plunge and dropped in two Interstate GC2-XHD 6 volt batteries wire up as 12 volt. Now it pops right off and runs better after the fresh gas has worked its way through the system.

Yours should run smoother and start better with fresh batteries and after the fresh gas works its magic. I included several bottles of octane booster and carburetor cleaner in mine.

[BFlinn181]

Originally Posted by Walkingant

hi,

I charged the batteries, both were at 100%--re-installed them into the RV,
the Onan generator only made a very faint "buzz" to let me know I was pushing the start button. Same as before.

I have cleaned what connections I can, it does still turn over once with the RV engine running, If I hook up jumper cables it starts up with an exterior gas source. (haven't had time to see if the gas line is clogged).

If it starts with engine running, it still sounds like your coach batteries are weak or have bad connections, particularly the ground. Use a multimeter and check voltage at the generator with engine off and on.

[Walkingant]

It will not start with the engine running, turns over about once, then buzzes like not enough juice. I did hook up jumper cables to the house batteries, and it fired right up.

So its new batteries for my next step.

Blew air through the gas line, no bubbles, just no resistance. Fuel level indicates just above half--RV is level. So still no gas from the main tank.

I had a Bounder, that would only pull gas out of the tank if the it was over 1/2 full--used a five gallon can and hose to run that generator. Would rather get this to work right.

Thanks for the feedback!!

[RVee'r]

How about this: try to siphon gas from your main tank to the Onan fuel pump. If you can't suck it through the fuel line then chances are your fuel pump can't either. Just be prepared to spit out fuel! (Maybe you could temporarily attach a length of clear tubing so you aren't drinking gas).

Sounds like the fuel pump is ok if you can run the genny from a temporary gas can.

[RVee'r]

More thoughts..... replacing your batteries may resolve your fuel issue as well because if the fuel pump isn't getting sufficient voltage from the battery, (via the control board), it's not going to pump fuel to the carb.

This from the Onan troubleshooting guide:

The pressure and flow of the fuel pump (and fuel filter) can be checked by temporarily disconnecting the fuel line to the carburetor and jumpering the FUEL PUMP pin on the control plug to battery positive. Take adequate precautions when handling fuel. If pressure and flow are normal, reconnect fuel line.

Hope this helps.

[Murf2u]

Originally Posted by Walkingant

I hooked up a jumper cable from my truck to the Onan generator, and disconnected the fuel line and replaced it with a longer hose and put the end in a gallon gas container.

It took a few tries, but the generator started and after a few coughs, ran well. I let it run the gas nearly out. Shut it off, hooked it back up to the RV gas tank (it has over 1/2 tank) Restarted the generator, started with one touch, it ran the gas out of the carburetor and line, but would not pull any gas from the RV tank.

Originally Posted by Walkingant

Blew air through the gas line, no bubbles, just no resistance. Fuel level indicates just above half--RV is level. So still no gas from the main tank.

I know this sounds like a dumb idea, but there's a reason the very first item in the trouble-shooting section of an owners manual says something like "Be sure it's plugged in.".

Check the entire fuel line from tank to genset for a fuel shut off.

I've seen folks install them so they can run the genset dry so as to not allow fuel to gum up the carb in storage.

If not, just run a new line, it's just rubber fuel line available at any auto parts house. With that ethanol junk in the fuel it's a good idea anyways.

[BFlinn181]

If there were a fuel shut off in the line, he wouldn't be able to blow through it with no resistance. I also would recommend try suctioning fuel from the line. If you get no fuel, I think I'd check the fuel line from the pick-up to the generator, maybe it has a hole in it, sucking air instead of gas. Other possibility, the pick up fell off into the tank.

[Midniteoyl]

Originally Posted by RVee'r

More thoughts..... replacing your batteries may resolve your fuel issue as well because if the fuel pump isn't getting sufficient voltage from the battery, (via the control board), it's not going to pump fuel to the carb.

This from the Onan troubleshooting guide:

The pressure and flow of the fuel pump (and fuel filter) can be checked by temporarily disconnecting the fuel line to the carburetor and jumpering the FUEL PUMP pin on the control plug to battery positive. Take adequate precautions when handling fuel. If pressure and flow are normal, reconnect fuel line.

Hope this helps.

[Walkingant]

Ok, got off work, crawled all over under the gas tank, finally was able to see on top of it, looking just behind the driver's side duallys. There is a huge hole in the gas line, Almost looks like a rat chewed on it, since there is nothing there to rub on it.

Took my iphone and reached up in there and took a picture. Yeah, there is a major hole.

Anyway, its in a bad spot of replacing it, can just reach it with one hand. Going to try tomorrow again to get the hose off the tank fitting..

They need a trap door from inside,...

[Walkingant]

Replaced the fuel line to gas tank...

blew air through it, can smell gas, no bubbles.

Sucked air through hose, can smell gas, but no gas came through

Put in another 7 gallons of gasoline, now show over 5/8 tank,
still no bubbles or gas to siphon.

I am guessing the pick-up in the tank fell off. And by the looks of it, the only way to fix that is lowering the tank--

Unless my gas gauge is off. . . . . . .