Onan 5500 wont start

[71stang99]

I had broke in my uni last summer but put the unit away for 10 months. It was a quick stowage so I didnt drain the fuel etc. Ive been in the unit for a month now and have started to address the generator issue. So today I drained all the fuel (as best as I could) and added 10 gallons plus fuel stabalizer to the tank. Up front I drained the fuel lines as best as I could by proming andy daringin the card with the float bowl screw. Long story short the unit tries to start after draining and re priming but it will just not continue to run. Any thoughts?

Thanks

 

[jmgratz]

I had broke in my uni last summer but put the unit away for 10 months. It was a quick stowage so I didnt drain the fuel etc. Ive been in the unit for a month now and have started to address the generator issue. So today I drained all the fuel (as best as I could) and added 10 gallons plus fuel stabalizer to the tank. Up front I drained the fuel lines as best as I could by proming andy daringin the card with the float bowl screw. Long story short the unit tries to start after draining and re priming but it will just not continue to run. Any thoughts?

Thanks

You will probable need to get the carburetor rebuilt. The fuel sitting in the carb will gum up the jets causing not enough fuel to keep it running. You could get lucky and spray in some carburetor cleaner but that will usually not work. For future reference, before storage or non-use turn off the fuel while running and let it run out of fuel so it will not sit with fuel in the carb. I have done this and never have any problems.

 

[71stang99]

I was hoping it would not need rebuilt. These generaters must be awefully sensative if the gum up that bad. Hopefully the carb cleaner will work. What about the fuel filter if there is one and where is it to either clean 0or change out?

 

[Rodbuster]

I had broke in my uni last summer but put the unit away for 10 months. It was a quick stowage so I didnt drain the fuel etc. Ive been in the unit for a month now and have started to address the generator issue. So today I drained all the fuel (as best as I could) and added 10 gallons plus fuel stabalizer to the tank. Up front I drained the fuel lines as best as I could by proming andy daringin the card with the float bowl screw. Long story short the unit tries to start after draining and re priming but it will just not continue to run. Any thoughts?

Thanks

Should the same procedure be used if you have LP?

 

[porthole]

For future reference, before storage or non-use turn off the fuel while running and let it run out of fuel so it will not sit with fuel in the carb.

I am going to disagree Jim. I would use stabilizer and make sure the genset runs long enough to get stabilized fuel through the unit.
Leave the fuel in. Run the unit once a month for 20-30 minutes. Even if it can't be run for several months it still should be OK.

The main reason for the monthly running is more to keep the cylinder walls lubed.

The only way to properly "drain" the carb for long term storage is to disassemble it.

Should the same procedure be used if you have LP?

No, LPG genny's have the fuel vaporized before it gets in the carb. E.g. a gas (non liquid) instead of gasoline. One of the issues with gasoline is as the actual fuel evaporates and the additives remain, and that gives us the grief.

 

[1231ChaseB]

Hi ! When you push the button to prime the genny put your finger's where the fuel pump is and see if it vibrate's ! My fuel pump is right underneath and easy to touch ! Anyway if it don't vibrate then probably the fuel pump has gone bad ! That's what happened to mine and it wasn't even out of warranty yet fortunately !
They say that the fuel pump should be relocated back to the gas tank but i kept mine where it was and so far it's still working !
chaseb

 

[jmgratz]

I was just saying what works for me. I put stabilizer in the fuel tank also. I do realize the proper way to store is the drain the fuel and 'dry out' the carb. When I was talking about storage I was talking about a week to a month storage not long term (months).

 

[porthole]

I still wouldn't drain it, even for a short time. If it works for you all is well. I was just using my experience in my "former career".

 

[wesley1963]

Another thing you need to check is the air intake. The mud daubers love to build there.

 

[wingfoot]

I had broke in my uni last summer but put the unit away for 10 months. It was a quick stowage so I didnt drain the fuel etc. Ive been in the unit for a month now and have started to address the generator issue. So today I drained all the fuel (as best as I could) and added 10 gallons plus fuel stabalizer to the tank. Up front I drained the fuel lines as best as I could by proming andy daringin the card with the float bowl screw. Long story short the unit tries to start after draining and re priming but it will just not continue to run. Any thoughts?




Thanks

You didn't say but what is your altitude? I'm sure you know that you can adjust your gen set's altitude settings. I have had problems with mine when traveling in altitudes above 7,000 feet. At those altitudes the air get thin/less density. My gin set would do the same thing yours is doing.
Possible cure..take the cover off and use a pencil/small screw driver and hold the choke butterfly open and try to start after priming..If it starts continue to hold the butterfly open until it warms up a bit...works for me.
Good luck

 

[jnbhobe]

I 'm with Duane put in a good stabilizer and forget it, has always woeked for me

 

[71stang99]

Hi ! When you push the button to prime the genny put your finger's where the fuel pump is and see if it vibrate's ! My fuel pump is right underneath and easy to touch ! Anyway if it don't vibrate then probably the fuel pump has gone bad ! That's what happened to mine and it wasn't even out of warranty yet fortunately !
They say that the fuel pump should be relocated back to the gas tank but i kept mine where it was and so far it's still working !
chaseb

I will have to check that but it was making a vibrating noise as I was trying to prime/start it right from the generator. It tries to runs and will fire for a second and just die, I know there cannot be 'old' fuel in the line as it should be mostly new gas with the stabilizer. When the unit was brand new it would fire right up after priming. The generator has a total of 2.4 hours on it and .4 of that was from yesterday trying to fire it up. For the car cleaner, is that taking the carb off and soaking it or just spraying it down the throat assembly behind the airfilter?

 

[71stang99]

Pulled the air cleaner off and it looks brand new. No obstructions at all.

 

[71stang99]

You didn't say but what is your altitude? I'm sure you know that you can adjust your gen set's altitude settings. I have had problems with mine when traveling in altitudes above 7,000 feet. At those altitudes the air get thin/less density. My gin set would do the same thing yours is doing.
Possible cure..take the cover off and use a pencil/small screw driver and hold the choke butterfly open and try to start after priming..If it starts continue to hold the butterfly open until it warms up a bit...works for me.
Good luck

At Vegas altitude and it was the same altitude as last year when it ran, the setting for the altitude is correct. I will try your suggestion. thanks.

 

[Chainsaw]

I had a lot of starting and running problems, had to change the pig tail from the propane> is yours gas or propane?

 

[71stang99]

I had a lot of starting and running problems, had to change the pig tail from the propane> is yours gas or propane?

Gas, the dang thing is brand new (and ran fine) so hopefully the carb cleaner will work.

 

[dougw]

Mine had a clogged fuel filter. It had only sat maybe a month since our last camping trip. I had pulled the fuel line and fuel would come out of it but appearently not enough. As soon as I change it the gen fired right up. cheap and easy try to fix plus everyone can use a new filter.

Doug

 

[porthole]

Mine had a clogged fuel filter. It had only sat maybe a month since our last camping trip. I had pulled the fuel line and fuel would come out of it but appearently not enough. As soon as I change it the gen fired right up. cheap and easy try to fix plus everyone can use a new filter.

Doug

Ethanol will play havoc will fuel systems, one of the drawbacks is how well it will "clean-dissolve" stuff plain gasoline won't, making filter changes required more often.

Filter would be a good next "try"

 

[71stang99]

okay I had some time to work with this again, took the carb off and removed what I thought were the jets and the float bowl cover. Cleaned all of it with a carb cleaner. So using the advice of another poster I can run it just fine but to keep it running I have to keep the butterfly valve closed, it seems like it just wants to open full and it dies. When I hold it just ajar it purrs like a kitten, what controls the choke? meaning the butterfly valve?

Thanks again!

 

[porthole]

That indicates that the jets or idle circuit is clogged/restricted. Closing the butterfly like that forces fuel to be pulled up through the vents into the Venturi.
How handy are you? If it was mine I would take it apart and rebuild it.

But, the problem with modern carbs is the idle circuits are sealed to prevent tampering. So if those circuits are clogged the carb body may need to be immersed in a cleaning solution.

Unless you are comfortable doing this, and are prepared to buy a new carb if you do something wrong, you might want to consider a tech.

Even doing that, there is a very good chance they may just replace the carb. Seems many modern mechanics have lost the skill of diagnosing and repairing, replacing it with guessing and parts swapping.