More Onan 5500 - sputters bad under load

[VetPartTimer]

I've had 8 trouble-free years with my Onan 5500 in my 2007 Toy Hauler. I'm just over 400 hrs and have done the basic maint up to now.

I had noticed in the last few trips, the gen was harder to start than usual. Took it a while to get primed, coughed and sputtered a bit before starting.

Then on the last trip I took I noticed that the rough starting was continuing into my trip.

I was prepping for another trip this summer when we had that massive heat wave, 110-112 degrees. While cleaning the RV I was running the gen and AC. After about 15 min or so, the gen sputtered real bad. Didn't die, but it was barely running. Shut everything down, waited a while and started it back up. Started and ran fine for a few until I put the AC back on. Again, horrible sputter.

So I figured it was time to do the fuel pump, fuel filters, spark plugs etc that I have read about on here.

Finally got around to it yesterday - all the above was completed.

Startup was rough again, but I figured as much after having it apart. Ran it for 10 min or so then turned on the AC. It sputtered momentarily but came back up to normal rpm and ran fine for 20-30 min.

With the AC running I turned on the microwave. Horrible sputter, had to shut it down.

Tried again after 30 min, it started rough again but ran fine once going. Turned on the AC and bad sputter again.

So I've got something else going on.

I went through the code process, it's comin up with a code 13, undervoltage fault.

I personally think the undervoltage error is due to the thing sputtering and barely running, this throwing that code. But I'm not a gen mechanic so I don't really know.

My gut (years of dirt bikes) tells me it's a fuel/carburation issue. I know how bad dirt-bike carbs get.

Several folks on this board buy and install new carburetors and that sometimes solves their prob. I'm thinking that might be the issue, but don't want to make a $250-275 purchase for nothing.

Does anyone know if these carbs are serviceable? Can you get the float bowl off so you can properly clean them? Or are they permanently sealed?

If it's not serviceable then I'm trying to decide if I should go for the new carb or am I just being stupid and should get it to a mechanic to deal with the undervoltage code and whatever the fix for that is?

Just curious what you all think.

[Hap_Hazard]

Allcool,

Thanks for the valve adjustment instructions. That'll be my next project.
For those asking about carb rebuilds or cleaning that is a very simple project. Carb removal is straight forward.

1) Remove fuel line at the carb bottom.
2) Remove electric plug for the shut off valve.
3) Remove two push on terminals for the electric choke.
4) Remove air filter and housing.
5) Disconnect the springs and rod on the right side of the carb.
6) Remove carb.
7) Unscrew electric fuel shut off valve and the fuel bowl comes off.
8) Remove the brass air valve from the shut off valve.
9) Remove the pin holding the plastic float and clean needle and seat.
10) Remove 3 cross tipped screws on top of the carb and using a
screwdriver remove the internal brass air tube.
11) Soak this tube and the brass fitting from the fuel shut off valve in
Sea Foam.
12) Re-assembly and re-install carb.
13) Job done

While exploring the above maintenance items I discovered one other procedure that should be done every 450 hours. Remove the spark arrestor plug and run the gen set for 5 minutes under heavy load. Be sure to do this in a safe location as hot sparks may be ejected from the exhaust. See your manual for the location of the plug as they vary from one model to another.
Hap

[allcool]

dedmiston wrote:


The forum has been crankier than usual lately. Google Chrome even had some fun with me and renamed my shortcut to "404 directory not found". Hah. Good one, Google.

Yup, noticed that.
'cranky' is a good way to describe forum software on some days. Gives our forum almost a human quality... lol.
Hmmm,,,,Makes me think of the future, maybe 20-50 years when probably Artificial Intelligence will be capable of who knows what human qualities...?

[dedmiston]

allcool wrote:

Y-Guy wrote:

allcool wrote:
Here ya go. Tried to post a Photobucket jpeg pic of the Onan 5500 shop manual, with a pic of the valve adjustment, but for some reason the forum keeps timing out and not posting my message..???

Sorry about that RV.net seem to have some issues some days I've run into it too. There's a bug somewhere. When it happens I go to woodalls.com and log in there, for some reason that portal works just fine when I try to post a link or photo.

No need to be sorry, not your fault. Web issues are part of the joy of message boards...lol
Ok, thought I might be doing something wrong. Tried to log on to woodalls.com and got this:

Service Unavailable

The service is temporarily unavailable. Please try again later.


Maybe powers at large are working on it now..?

The forum has been crankier than usual lately. Google Chrome even had some fun with me and renamed my shortcut to "404 directory not found". Hah. Good one, Google.

[allcool]

Y-Guy wrote:

allcool wrote:
Here ya go. Tried to post a Photobucket jpeg pic of the Onan 5500 shop manual, with a pic of the valve adjustment, but for some reason the forum keeps timing out and not posting my message..???

Sorry about that RV.net seem to have some issues some days I've run into it too. There's a bug somewhere. When it happens I go to woodalls.com and log in there, for some reason that portal works just fine when I try to post a link or photo.

No need to be sorry, not your fault. Web issues are part of the joy of message boards...lol
Ok, thought I might be doing something wrong. Tried to log on to woodalls.com and got this:

Service Unavailable

The service is temporarily unavailable. Please try again later.


Maybe powers at large are working on it now..?

[Y-Guy]

allcool wrote:
Here ya go. Tried to post a Photobucket jpeg pic of the Onan 5500 shop manual, with a pic of the valve adjustment, but for some reason the forum keeps timing out and not posting my message..???

Sorry about that RV.net seem to have some issues some days I've run into it too. There's a bug somewhere. When it happens I go to woodalls.com and log in there, for some reason that portal works just fine when I try to post a link or photo.

[allcool]

Hap Hazard wrote:
Allcool

Checked my manual and I find no details on adjusting the valves. It refers you to an authorized dealer. Not an option in my remote area.

Do you have the details on how to do this maintenance? Posting that information here might help many of us.

Thanks,
Hap

Here ya go. Tried to post a Photobucket jpeg pic of the Onan 5500 shop manual, with a pic of the valve adjustment, but for some reason the forum keeps timing out and not posting my message..???
I've posted plenty of pics here before, but lately when trying to 'preview' my message or post jpegs, forum times out with an error message..???

ADJUSTING VALVE LASH
Valve lash is adjustable through the maintenance
access opening on gensets with enclosures. Access
to Cylinder No. 1 requires removal of the air filter
enclosure. See Page 8-1, 8-8 or 8-13, depending
on fuel system.
Note: For accurate adjustments, valve lash
must be adjust when the engine is at room temperature.
Adjust valve lash (Figure 9-2) for all valves to
0.004 inch (0.01 mm). Torque the adjustment lock
nuts to 6.5 lb-ft (8.5 N-m) and recheck lash.
The following procedure is recommended, noting
that the intake valves are the upper ones and the exhaust
valves the lower ones and that Cylinder No. 1
is to the left (generator side) and Cylinder No. 2 to
the right:
1. Remove the spark plugs so that the engine is
easier to turn over.
2. Use a socket wrench on the generator pulley
nut to turn the engine. Remove the snap-in cover
in the access hole in the drip pan. Always
turn clockwise so that the nut does not loosen.
3. Remove the valve covers. Have rags in place
to catch the oil that spills out.
4. Turn the engine until the Cylinder No. 2 intake
valve (top) is at maximum lift. Then adjust Cylinder
No. 1 intake valve lash.
5. Turn the engine until the Cylinder No. 2 exhaust
valve (bottom) is at maximum lift. Then
adjust Cylinder No. 1 exhaust valve lash.
6. Turn the engine until the Cylinder No. 1 intake
valve (top) is at maximum lift. Then adjust Cylinder
No. 2 intake valve lash.
7. Turn the engine until the Cylinder No. 1 exhaust
valve (bottom) is at maximum lift. Then
adjust Cylinder No. 2 exhaust valve lash.
8. Secure the valve covers using new gaskets.
Torque the cover screws to 5.5 lb-ft (8 N-m).
9. Replace the spark plugs and pulley nut cover

[allcool]

VetPartTimer wrote:
Ignition coil.

Bad part is that the gen has to be pulled out of the trailer so the gen can be taken fully apart to get to the coils.

Don't even ask how much. Part is only $30

Glad you got it fixed...
First time I've heard of a coil going bad in these 5500 gen-sets.

[Hap_Hazard]

Allcool

Checked my manual and I find no details on adjusting the valves. It refers you to an authorized dealer. Not an option in my remote area.

Do you have the details on how to do this maintenance? Posting that information here might help many of us.

Thanks,
Hap

[KKELLER14K]

DANG it COIL!! Holly whatever!! the one thing I said in my rant..OK so let's see if it is what it is when it really runs..LOL! But Im so glad there is a victory here...ok so I learned that there is two plugs...LOL!

[Y-Guy]

Ack! That bites. Any word on the cause?

[Chakara]

Ouch - but thanks for letting us know!

-Chak

[VetPartTimer]

Ignition coil.

Bad part is that the gen has to be pulled out of the trailer so the gen can be taken fully apart to get to the coils.

Don't even ask how much. Part is only $30

[Y-Guy]

Good call VetPartTimer. Thanks for the future update.

[VetPartTimer]

Taking it in to the shop tomorrow morning, I'll provide an update afterwards.