Onan Gererator starting problem

fmurray3

Member
I am having a problem starting the generator on my 2008 Cyclone 3210. I normally start and run it for an hour every month. the starter will turn over but the generator will not fire up and run. There is 1/2 tank of stablized fuel and it is flowing to the generator. I cannot find any electronic problems and the battery has a full charge. Does anyone have any other Ideas or areas to check? The generator is a Onan 5500.
 

alkyspeed

Active Member
If it is not even trying to fire, the carburetor float might be stuck and not letting fuel into the carb. Loosen the screw on the carb bowl and see if you get fuel out of it. (put a small hose on the spigot on the bottom of the bowl to catch fuel) If no or very little fuel comes out then gently tap the float bowl with a screw driver handle or some other small tool . Try to start the gen set, if still no start check again for fuel at the carb. Hope this helps. ;)
 

Luckyhat12

Active Member
I did all of the above and it still didn't start. I just spent the last two days diagnosing and couldn't figure it out so I ended up taking the carb off and taking the float and needle out and spraying carb cleaner through everything.

It wouldn't start and my gauge read real close to empty so I thought i had run out of gas. I went to the store and got 10 gallons and stab-iled it and poured it in... no dice. I then cracked the drain on the carb and some little black trash came out onto the papertowel that I put under it. about 3 specs. Not a lot mind you. When I was priming, the fuel pump kept knocking like it had air in the line. So I pumped about a half gallon or more with prime through the carburetor and just left the hose hooked up to the carb. Still no start. Well... I could get it to start, but I had to manually chose it the whole time to get it to run. It would die under load. So I pull the fuel filter that is on the tank side of the fuel pump and tap it out... nothing came out. I blew through it both ways and still nothing. When I unhooked that hose from the tank though I still couldn't get any fuel from the tank hose to drain so I took my air compressor and blew back in that hose and tried to get it to bubble back in the tank. I was alone so I never could verify bubbles. I hooked it back up and still no start...

So then I start tearing the front off and pull the carb. I took the second fuel filter off and pointed it to my fuel tank and did the prime and I was blowing all kinds of fuel through there after the pump caught back up. I decided it wasn't in the fuel pump nor that filter so I started into the carb. I took the bowl off and cleaned everything, took the float and needle out and sprayed the jets with carb cleaner and took the "accelerator pump cover" (it wasn't, but that is what the cover looked like) off and sprayed all the jets out there and put it back together. When I put it in I opened the drain again and pumped about a half gallon of fuel through it again just to make sure it was flowing right/better and then closed the drain and continued to prime to fill the bowl and see if I could get some fuel in there. First couple of cranks didn't sound so good but it eventually came around.

After that I ran it for about an hour and a half under a pretty full load to get it to work itself out. I don't have a tachometer but it sounded a little low in the RPM range. It held the load but I need to check the RPM to make sure I don't need to move up the governor spring.

That is my story and it took a while to get there. If I had to do it again I would just take the 4 bolts to get the carb off and pull the fuel filter from the side of the carb and prime to make sure there is plenty of fuel getting there. then I would pull the bowl off and clean the needle and seat and try again. it isn't real hard but I think I will buy some carb gaskets next time I am in to get an oil filter so I don't have to worry about tearing one the next time I am in there.
 

krehlert

Still kickin and screamin
If you can get your hand on a voltmeter with frequency (Hz) it should be running around 60-63 Hz. This is the same as engine rpm but measured in the electric way.
 

viking4545

Member
My generator would sometimes run and sometimes not. Other times it would prime up, run for an hour or so, then die, wait a couple of hours and it would start again. I read somewhere that there Onan had a bad run of fuel pumps, and as it turns out I had one. Since it was replaced I havent had a problem.
 

fmurray3

Member
Finally got tired of tring to figure it out and took it to the Cummings warranty shop they check it and said the fuel line was clogged, blew it out and it's run great since (10 minute job and I spent hours on it). It seemed to be getting fuel when I checked it but then I'm just an ex-cop so what do I know about generators. Like they say sometime it's better to let the pros do it.
 

Luckyhat12

Active Member
Finally got tired of tring to figure it out and took it to the Cummings warranty shop they check it and said the fuel line was clogged, blew it out and it's run great since (10 minute job and I spent hours on it). It seemed to be getting fuel when I checked it but then I'm just an ex-cop so what do I know about generators. Like they say sometime it's better to let the pros do it.

I actually thought the same thing so I tried to blow back in mine and all it did was pressurize the system and make it spit back on me.

If you had seen all the stuff that I have gotten out of my tanks you would understand why I feel this is a viable issue. I have had the valve replaced on my grey tank because there was metal and junk in it. Had it out for cleaning twice before the replacement.

I feel that there is still an obstruction in mine but it is running so I am going to go with it. I do think I will be blowing out the line again in the future. I just did too many steps at one time to officially narrow it down to one item.
 

blackfin

Member
My generator had 2.8 hrs when it would run for a few seconds and stall finally got to where it would not start, but I could prime the system and the generator would run. I also changed the low pressure fuel pump after checking the filters and now am up and running...at least for now.
 

Luckyhat12

Active Member
Well. I can prime it, then try to start it and it only runs half speed and not enough to trip the power transfer switch. Then I can stop it, prime it for at least 30 seconds and start again. This time it will either sputter and do the same thing and I can stall and re-prime or it will kick off and run. Once it is running it runs but I still think it isn't at full power. I am going to try to get a replacement pump before the warranty is out and see if that fixes it. I may also put a one way check ball valve near the tank to keep the fuel in the lines after it is shut off. They aren't that expensive now that I have been looking.

Chris
 

Bob&Patty

Founders of SoCal Chapter
Chris, just for grins and giggles, take the fuel line off and look thru the hose both ways. I have seen fuel lines come apart inside and a flap of rubber almost or fully shut off fuel flow. Just a thought. Bob:D
 

Luckyhat12

Active Member
Thanks Bob. I thought about that too but the fuel line runs from the back of the camper all the way to the front of the camper. It is about 40ft of fuel line.

I had the same thing happen on a boat twice actually. Once on an outboard motor from the fuel pump to the carburetor and again on an inboard. The inboard was a much more difficult fix though.

Thanks for the suggestion. I think if I get to that point I will just take the whole thing out and replace that hose. It is less than a year old so I am betting that there is a pump issue before the hose unless it is routing and causing an air bubble to be trapped in there allowing the fuel to flow back toward the tank requiring significant priming each time.
 

Bob&Patty

Founders of SoCal Chapter
Chris, your welcome. BTW, if you have to replace the fuel line, maybe you might replace it with better stuff. Braided stainless might be a better line. But cost:eek:?? Have you ever considered putting another fuel pump inline? Up to you. Bob:D
 

Luckyhat12

Active Member
So you guys want to laugh. It has been almost a year since this thread and I am still having issues with my generator. I have run it the hour every other month or so and I didn't think much about it because the last time I had to run it all weekend was when I was in Indianapolis for the motorcycle races.

My camper was in the shop for a lot of the spring and I told the dealer that I had a fuel pump issue with my generator...... they checked the carb and said that the adjustment on the carb wasn't working anymore and told me I needed a new carb... I said no, it is the fuel pump. They said that if my fuel pump was running it was pumping. What a crock. The pump runs.. it doesn't pump well. So we went round and round and I told them just to not touch it because I thought they were being idiots and it just made me mad.

Fast forward a while now when I am prepping for another long trip...

So I go out and my genny runs for a bit and then stalls out, I put a load on it, and it runs and then stalls out. When it is running it is running great so me and that whole carb issue just don't jive. So I start troubleshooting, my genny always takes priming more than once to get it to start (read fuel pump issue) and then when it starts, it runs rough till it can get a good vaccuum and pull fuel in and then it starts to run better. So I go out, prime it... it runs... then quits. For giggles, I put a hose on the carb drain and open the drain screw... NADA drop. So I hit the primer button... it won't even fill the carb bowl. So I start to trouble shoot some more... I pull the fuel hose off the carb and stick it in a bottle and prime. It trickles a bit and then changes sound and starts to flow so I am thinking it may not be the fuel pump. So I pull the carburetor and take the fuel filter off and pull the float bowl and make sure that the needle and seat aren't stopped up because I am thinking that if the needle is stuck that it could be causing enough pressure buildup to make the fuel pump start bypassing and not feeding anymore. I get it apart and clean it up and make sure it isn't plugged and put it back together. I have to prime it 3 times to get it to fire back off (read still think fuel pump issue) and the pump changes sounds again and fills the fuel bowl on the carb and the genny starts. Runs great... for about 20 minutes and dies. At this point I am thinking that the stinking needle and seat can't be stopped up again so just for giggles, I stick the piece of fuel line back on the carb bowl and open the drain.... once again, NADA gas there.

I didn't like the clamp that was on the fuel line at the filter on the side of the carburetor so I left it off and was going to replace it with a better clamp before I ran it much. When it died again, I pulled the fuel hose off the carburetor and hit the primer button.... STINKING FUEL PUMP WOULDN"T EVEN PUMP FUEL WITH NO RESTRICIONS.... I TOLD THEM IT WAS A FUEL PUMP ISSUE BUT NOOOOOOOOO.

So now I am looking for a fuel pump so I can get my genny working like it was supposed to over a year ago. I think I am going to mount a pusher pump back at the tank so it doesn't have to suction fuel 40 feet before it gets to the fuel pump and causes it to burn the new pump out.

That has been my biggest issue the whole time... an intermittent fuel pump that pumps when it wants to and doesn't when it opts out. .... Maybe this will help someone else with their problem diagnosis.
 

FLOYD PHILBROOK

Nevada Chapter Leader
Cyclone-fuel systems

Electric fuel pumps are made to pump fuel not suck fuel for any distance. they have a backflo valve built into them, buy if running over a few feet will not work. Most vehicles have them built into the tank or right outside 0f the tank as a pusher. Hope this helps you. FLOYD PHILBROOK
 
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