Onan 5500 not starting...partially solved

Onan 5500 not starting...partially solved (now fully solved...I think)

We have the Onan RV QG 5500 EVAP installed in our Cyclone. We try to run it for 30-60 minutes per month, minimum, and it currently has 49 hours on it. We were pretty good about that the first year, then we ran into the 2014 holidays. Well, it was Oct/Nov that we last ran the genny. This week, I tried running it and it would not fire up. As soon as I let go of the start button, it would cut out. After lots of searching regarding error code 36, I figured the carb was gummed up. The fuel in the tank has Sta-bil mixed in, so it should be OK.

I used a some Sea Foam inside the carb and after a few repeated applications, I can now run the genny pretty well...with no load. The idle is constant with no fluctuation As soon as I turn on the main fan, there is a slight surging, but still remains running. As soon as I switch to air conditioner, the surging increases and eventually the power cuts out. Now, the generator is still running, but the trailers converter (?) kicks off an there is no more power to the rig. After 20-30 seconds, the converter kicks back on and we have power again. Try running the air conditioner again...repeat the process.

I know the fuel in the tank is 87 octane with Sta-bil. I believe I put it in around August. My thoughts are to drain the tank and add 91 octane with a can of SeaFoam. If I can run the generator on idle for a while, that should clear the crap 87 octane and get some SeaFoam mix into the carb. I would then shut down the genny and let it sit for a while to eat up the gunk. Hopefully after 30 minutes or so, I can fire it up and run with a load.

Does this sound about right, or am I totally missing the bigger picture with the power cutting out under load?

Thanks,

Jeff

There is a situation involving low batteries that can cause the symptoms you describe. Make sure your batts are charged completely with a independent charger, and your master battery switch is in the on position. Fill with fresh gas and add correct amount of additive (if you desire an additive,) personally I don't think you need it. See if a fully charged battery wont fix your problem.

If your transfer switch is dropping, the voltage output of the generator L1 line is probably dropping below 110V under load. The control board on the transfer switch looks for a good 110V to actuate and hold the contactors.

It does sound like you're making progress toward getting it running right.

I do not think it is a gumming issue. There hasn't been enough time to make your carb gum up and you have some sta-bil in the system. Once a gummed up carb starts running and gets fresh fuel it will clean up the gummed stuff. I would look at the fuel filter or a weak pump.

As to using a mid-grade or premium fuel you are wasting money. Octane number is a measure of resistance to igniting. The higher the number the more difficult to ignite the fuel.

It can't hurt to put a fuel system cleaner (I like Techron by Chevron) in the tank but be sure to use it in the ratio advertised. Surging can be caused by a mixture that's too lean perhaps caused by gumming.

Stabil is a very good product but they only advertise protection for a couple months. If you know the generator won't be used for a while it's always best to drain the tank as best you can then run the generator til the fuel lines are dry.

While typing this another thought came to mind. Can you hear the fuel pump chattering when you hold the start switch? If so, you are drawing some air which may be contributing to your problem

Your issue is not the fuel/grade. If it starts without a load and stays running it is another problem. As others said, you should check batteries and other components. If it makes you feel better, yes run the generator to use up the fuel. I don't recommend draining the fuel unless you know for a fact it has been in the tank for over a year.

This is just my opinion:

I have a 2014 Cyclone, 18 months old. I filled the fuel tank with premium non ethanol gas and one can of seafoam when new. I run the generator periodically, but not regularly. It has 42 hours on it. It has never had an issue starting. I use premium gas in case the octane degrades during storage. I use seafoam for its cleaning agents. I use non ethanol gas because it does last longer than 10% ethanol gas when stored for months. With the heat and humidity here in south Louisiana, ethanol gas does not store much longer than 12 - 14 months. I have years of experience with classic cars to prove it.

In my Cyclone, I replace the gas by regularly filling my lawn mower, four wheeler and scooters. I figure I turn the tank over once every 12 to 14 months. I will be topping it off in a few weeks when mowing starts again. This also keeps my fueling station pump 'exercised'.

I have the batteries plugged in right now, just to make sure they are at 100% when I try again tonight.

I guess I don't understand why the batteries would affect the running of the generator. I understand that you need a little juice to get it started, but isn't the purpose of the generator to provide power?

I thought I had been able to run the air conditioner in the past, even when the batteries were low. I guess I will see if that is the problem. As to draining the fuel tank, there may only be 5 gallons or so. I am also thinking of routing the pump pickup hose to a small tank of known good gas. If that works, then it could be the fuel.

Step 1. Try starting generator when I get home (batteries should be at 100%)
Step 2. If generator starts and idles normal, apply load of air conditioner.
Step 3. If a/c runs without surging, let it run for an hour, then idle down to shut off.
Step 4. If a/c surges while running, re-route fuel pickup line to known good fuel source.
Step 5. Repeat steps 1-3.
Step 6. If step 5 is successful, drain fuel tank and replace with good fuel. If Step 5 is not successful, call somebody.

I am glad to hear that the problem is not gumming of the carb. Since that is clearly excluded in the Onan warranty. If there is another more serious problem that is causing it, then it will be covered.

Ladiver said:

We have the Onan RV QG 5500 EVAP installed in our Cyclone. We try to run it for 30-60 minutes per month, minimum, and it currently has 49 hours on it. We were pretty good about that the first year, then we ran into the 2014 holidays. Well, it was Oct/Nov that we last ran the genny. This week, I tried running it and it would not fire up. As soon as I let go of the start button, it would cut out. After lots of searching regarding error code 36, I figured the carb was gummed up. The fuel in the tank has Sta-bil mixed in, so it should be OK.

I used a some Sea Foam inside the carb and after a few repeated applications, I can now run the genny pretty well...with no load. The idle is constant with no fluctuation As soon as I turn on the main fan, there is a slight surging, but still remains running. As soon as I switch to air conditioner, the surging increases and eventually the power cuts out. Now, the generator is still running, but the trailers converter (?) kicks off an there is no more power to the rig. After 20-30 seconds, the converter kicks back on and we have power again. Try running the air conditioner again...repeat the process.

I know the fuel in the tank is 87 octane with Sta-bil. I believe I put it in around August. My thoughts are to drain the tank and add 91 octane with a can of SeaFoam. If I can run the generator on idle for a while, that should clear the crap 87 octane and get some SeaFoam mix into the carb. I would then shut down the genny and let it sit for a while to eat up the gunk. Hopefully after 30 minutes or so, I can fire it up and run with a load.

Does this sound about right, or am I totally missing the bigger picture with the power cutting out under load?

Thanks,

Jeff

Click to expand...

The surging of the generator is probably what's causing the power outage under load. As the RPM drops so does the volatage output knocking the transfer switch offline followed by the normal delay before it reingages. I've had problems with Ethonal mixed gas gumming up the carbs on some of my small engines like the 0-Turn, Miller welder, pressure washer, etc. Sometimes they will clean up on there own when I get them running and occasionally I have to take the carb apart and spray it out with some carb cleaner. The two most common areas I have found a problem has been the main jet and the other is the fuel shutoff soleniod on carbuerators that use the electric shutoff. The soleniod is just a little electro magnet with a metal plunger and when this plunger gets gummed up the magnet isn't stroung enough to pull it full open and can cause the engine to run lean or not start at all. Be careful if you take the carb apart on your Onan as it is difficult if not impossible to find a carb kit so you don't want to ruin any gaskets. I ended up buying a new carb for my Onan a couple months ago to fix the problem I was having and it has been running good ever since. I lucked out and found a new carb in a sealed box on ebay for a good price, saved me about $100.00.

Jeff - did you look at my post about the genny running issue? Link in my signature at the bottom.

Some additional thoughts. Batteries should not be an issue as long as the genny starts - unless your batteries are defective, in which case the genny will not start (without a jump).

The caps are non venting, try loosening the cap and see if you get an inrush of air, maybe even hear the tank pop.
Ethanol fuel sucks, and degrades quickly. I would suggest using a stabilizer designed for ethanol laced fuel. ValvTec was one of the first, I use it all the time.

I fill the tank at the end of the season with probably double the dose of the ValvTec additive, run and shut down. I'll run the genny a couple of times over the winter for an hour, 45 minutes of that under heater loads (two AC units with heat strips).

I don't worry too much about the spring fuel use as we go to the spring Dover race and I will burn at least 1 full tank of fuel there. If I have any doubts as the fuel (oder from the tank) I'll pump as much as possible out and put it in the car.

Higher octane is a waste of cash, unless you need it for the toys. If we are traveling somewhere where the stations may be fewer and further between I will dump as much as I can and add high test (need it for the bike).

Seafoam has a loyal following and may help.

The bottom line though is our issue is caused by the EPA. We are stuck with ethanol fuel which ONLY benefits the farmers, super lean carburetors and sealed adjustments. On the Onan you can longer even get a carb overhaul kit.

Check the fuel solenoid trick I bring up in my Onan thread,

Duane,

I did see your thread and I thought about just replying to that but decided to just start a new, fresh, one. I did not try tapping the solenoid, but will try that tonight. That seems like it just might work.

I did find a local supplier with a carb in stock for $217. I may pick it up, then try to clean the old one. It probably does not hurt to have a spare on hand if cleaning it fixes it. Or, there are a TON of Onan 5500 owners that would buy it. ;-)

Aren't the new onan 5500 fuel injected.

Ladiver said:

Duane,

I did see your thread and I thought about just replying to that but decided to just start a new, fresh, one. I did not try tapping the solenoid, but will try that tonight. That seems like it just might work.

I did find a local supplier with a carb in stock for $217. I may pick it up, then try to clean the old one. It probably does not hurt to have a spare on hand if cleaning it fixes it. Or, there are a TON of Onan 5500 owners that would buy it. ;-)

Click to expand...

That is the best price I have seen for the carb. It does stink that we can't rebuild them. If I decide to buy the carb it will be so that I can try and take apart the old one. I have no issue with taking it apart, it is the getting it back together and sealed without fresh gaskets that concerns me. Having a spare would make it less of a concern.

The original number I have doesn't show up on any searches.
Searching for Onan 0531-0765 yields results with this number 0541-0765.

The difference appears to be the fuel inlet. The original use to have a second filter screwed into the carb about where the newer number has a typical fuel inlet tube.

Compare this ebay picture for the 0541 to yours.

Mine looks identical to the 0541. I do not have the second filter.

I also agree about taking it apart. I am not worried about that part. It is getting it back together again. If I have a new one, then I have nothing to lose in trying.

Ladiver said:

I have the batteries plugged in right now, just to make sure they are at 100% when I try again tonight.

I guess I don't understand why the batteries would affect the running of the generator. I understand that you need a little juice to get it started, but isn't the purpose of the generator to provide power?

I thought I had been able to run the air conditioner in the past, even when the batteries were low. I guess I will see if that is the problem. As to draining the fuel tank, there may only be 5 gallons or so. I am also thinking of routing the pump pickup hose to a small tank of known good gas. If that works, then it could be the fuel.

Step 1. Try starting generator when I get home (batteries should be at 100%)
Step 2. If generator starts and idles normal, apply load of air conditioner.
Step 3. If a/c runs without surging, let it run for an hour, then idle down to shut off.
Step 4. If a/c surges while running, re-route fuel pickup line to known good fuel source.
Step 5. Repeat steps 1-3.
Step 6. If step 5 is successful, drain fuel tank and replace with good fuel. If Step 5 is not successful, call somebody.

I am glad to hear that the problem is not gumming of the carb. Since that is clearly excluded in the Onan warranty. If there is another more serious problem that is causing it, then it will be covered.

Click to expand...

Step 1. Success
Step 2. FAIL go to Step 7 I tried Duane's "rap" and I just don't have the magic.
Step 7. Remove carb and make sure to get SeaFoam in EVERY opening. Let sit for 1 hour. Re-assemble and start over.
Step 1. Success and smoked out the neighborhood.
Step 2. FAIL. Go to step 4.
Step 4. New fuel line to fresh fuel. Drained all existing fuel from filter/pump/hose and carb.
Step 1. Success
Step 2. FAIL

Now I will order a new carb, and might as well do an oil change and replace fuel/oil/air filters at the same time. If it still does not work, I call Onan and see what they say. Clearly, it will be something more serious.

I tested the pump by priming the system and seeing the fuel spit out the end. It definitely has plenty of spray. I also checked for debris in the fuel filter. Nothing there either.

I have a buddy at work that was a mechanic and spent several years rebuilding the carb. I will take it to him tomorrow.

Any other ideas as to what to check?

Thanks,

Jeff

Do you have a auto generator start of some such system installed? I bet money you do not have a carb problem. Have you checked the governor? That control rod must respond immediately, and if it is dragging, it could cause you all kinds of problems. Especially if you have an EMS system.

Do you live in an area near salt water? Did you spend some time last year in a place where there was a sea breeze? The Onan has delicate parts that are easily corroded by road grime and coastal atmospheres.

The 36 code does not mean anything except that the Onan shut down without being turned off.

Ladiver said:

Step 1. Success
Step 2. FAIL go to Step 7 I tried Duane's "rap" and I just don't have the magic.
Step 7. Remove carb and make sure to get SeaFoam in EVERY opening. Let sit for 1 hour. Re-assemble and start over.
Step 1. Success and smoked out the neighborhood.
Step 2. FAIL. Go to step 4.
Step 4. New fuel line to fresh fuel. Drained all existing fuel from filter/pump/hose and carb.
Step 1. Success
Step 2. FAIL

Now I will order a new carb, and might as well do an oil change and replace fuel/oil/air filters at the same time. If it still does not work, I call Onan and see what they say. Clearly, it will be something more serious.

I tested the pump by priming the system and seeing the fuel spit out the end. It definitely has plenty of spray. I also checked for debris in the fuel filter. Nothing there either.

I have a buddy at work that was a mechanic and spent several years rebuilding the carb. I will take it to him tomorrow.

Any other ideas as to what to check?

Thanks,

Jeff

Click to expand...

Jeff, did you try rapping the solenoid?

One question is, does it sputter and die? OR, just shut down as if you shut it down with the switch?

Sputtering and dying is going to be different than a grounding of the magneto. If it shuts down as if you manually shut it down, then you have something that is grounding the magneto, if it sputters and dies then you have some other problem such as the governor control rod dragging.

Does the generator shut down with the Air Conditioning load, or will some other load such as the microwave kill it?

This would be a good thread to have a video with a narrative "...and at the 38 second mark I turned on the AC" etc.

Jeff...before you loosen the bolts/nuts holding the carb, check them for tightness. If you find that they will easily accept a quarter turn or more you may have found the problem.

Jim.Allison, I do have an auto-gen start installed. I have not checked the governor Unfortunately, a mechanic I am not, and did not go beyond the carb yet. But after this, I may be a little more qualified than some of the local shops around here. You also mentioned something about salty air. I did spend 4 days last year camping at the beach, but that is the only time I was exposed tot he sea breeze. I did a visual on everything and did not see anything that appeared to be rusty or corroded. Is there anything specific I should look at?

They symptoms are that the generator starts fine with the breakers off. I let it idle for a minute or so, then flip the 2 breakers on. Everything still is OK. I go into the trailer and can hear the converter activate and supply generator power to the rig. At that time, I can view my inverter controller and see that the batteries are charging and the amps that are being delivered. I do see the "surge" of amperage (+/- 10-15 amps). The lights visibly dim during the surge, but the generator sounds the same. I can power on the main fan and hear the surge while it is running. When I turn on the air conditioner, it runs for a few second and surges. That is then the converter kicks the generator power off. Keep in mind the generator is still running and no error codes are being produced. Unfortunately, I have not tried another load yet. Maybe tonight or this weekend.

Duane, I tried rapping the solenoid, but that did not work. Then I tried beating it. Still nothing. Next step would be a .45 to it! I did see that I can buy a replacement. That means I can remove it and try to manually force the plunger.

Neale, as you said, it would be better with video. I thought about that after I removed the carb for the last time last night. I am half tempted not to clean it up today, but reassemble and video everything. After reading Jim.Allison's comments, I bet cleaning it even more will not do much. Either way, I will get the GoPro set up to film the re-installation of the carb and the future testing.

Thanks,

Jeff