Continued Onan Issue

[FLRosebud]

I'll try and make this as short as possible, as it's been discussed here before. We have a 2006 National SeaBreezeLX on an F53 chassis. Onan 5500 Gold. First 3.5 years I owned the MH genny ran perfect, no issues. At 1000hrs I wanted to change the spark plugs. One I was not able to get because the plug was too close to the frame (poor design, but I digress). So took it to our RV repair shop, and they had to drop the genny about 2" to get the plug out. However, since then we've had issues with the genny stopping for no apparent reason, both in the driveway or on the road. The code is 36, which says generator stopped with no electrical input, meaning a fuel issue. So I've changed out the fuel pump, blown out the lines, experimented with full gas tank down to 1/4 of a tank, driving and parked. Also did a carb clean per a youtube video, which made it purr like a kitten when it's running. Have had discussions with other National owners who are friends of mine. Still will shut off, sometimes in 30 minutes, most times after a few hours.

Was at the Tampa show yesterday, and talked to a couple of the Onan guys. They were not techs, so wasn't that productive, but one of them said he felt like it might be vapor lock. He then showed me a 4000 they had there, and there was an air diverter around the fuel line going into the carb. Dang, mine doesn't have that. So now I'm wondering if the fuel line was insulated, and when the shop finished with the spark plug (I had them change the fuel filter and oil while it was there as well since they were working on it) they left it off. As of right now there is no insulating sleeve on the fuel line. Should there be one? Is my solution this simple?

Any thoughts?

Al

[craigd853]

Originally Posted by FLRosebud

I'll try and make this as short as possible, as it's been discussed here before. We have a 2006 National SeaBreezeLX on an F53 chassis. Onan 5500 Gold. First 3.5 years I owned the MH genny ran perfect, no issues. At 1000hrs I wanted to change the spark plugs. One I was not able to get because the plug was too close to the frame (poor design, but I digress). So took it to our RV repair shop, and they had to drop the genny about 2" to get the plug out. However, since then we've had issues with the genny stopping for no apparent reason, both in the driveway or on the road. The code is 36, which says generator stopped with no electrical input, meaning a fuel issue. So I've changed out the fuel pump, blown out the lines, experimented with full gas tank down to 1/4 of a tank, driving and parked. Also did a carb clean per a youtube video, which made it purr like a kitten when it's running. Have had discussions with other National owners who are friends of mine. Still will shut off, sometimes in 30 minutes, most times after a few hours.

Was at the Tampa show yesterday, and talked to a couple of the Onan guys. They were not techs, so wasn't that productive, but one of them said he felt like it might be vapor lock. He then showed me a 4000 they had there, and there was an air diverter around the fuel line going into the carb. Dang, mine doesn't have that. So now I'm wondering if the fuel line was insulated, and when the shop finished with the spark plug (I had them change the fuel filter and oil while it was there as well since they were working on it) they left it off. As of right now there is no insulating sleeve on the fuel line. Should there be one? Is my solution this simple?

Any thoughts?

Al

Hello and sorry for your issues. The answer to your question is yes this could be the issue. First, I assume when you have the generator running you do have the side cover installe correct? Mine has a squirrel cage on the bottom of the unit and it will not cool properly if the side panel is not on the generator. I'm sure others will be along here shortly to offer some more advise, good luck and let us know how it turns out.

[wopachop]

Is the float bowl running dry? Or maybe the solenoid is closing and shutting down flow?

Next time it happens drain the float bowl to see if indeed your carb is running out of fuel.

[FLRosebud]

Originally Posted by wopachop

Is the float bowl running dry? Or maybe the solenoid is closing and shutting down flow?

Next time it happens drain the float bowl to see if indeed your carb is running out of fuel.

Good idea. When you say solenoid do you mean fuel pump? The line goes from the tank to the filter to the fuel pump to the carb.

Al

[FLRosebud]

Originally Posted by craigd853

Hello and sorry for your issues. The answer to your question is yes this could be the issue. First, I assume when you have the generator running you do have the side cover installe correct? Mine has a squirrel cage on the bottom of the unit and it will not cool properly if the side panel is not on the generator. I'm sure others will be along here shortly to offer some more advise, good luck and let us know how it turns out.

Yes, the cover is on. I've not seen a squirrel cage under the genny. I'll have the RV over later this weekend, so I'll take a look.

Al

[craigd853]

Originally Posted by FLRosebud

Yes, the cover is on. I've not seen a squirrel cage under the genny. I'll have the RV over later this weekend, so I'll take a look.

Al

What kind of temperatures outside are we talking about when your generator shuts down? I believe one of the people who respnded explained that you should check the float bowl to see if there is gas in the bowl when this happens. This would definitely tell you rather you have vapor lock or a fuel pump issue. On my onnan 5500 the squirel cage is under the metal cover on the bottom side looking at it from underneath. Not going to swear to it but I believe there should be several small breathing hole and the squirrel cage is right behind this. Sorry I cant be of more help but my onnan is a little bit newer than yours.

[wopachop]

Originally Posted by FLRosebud

Good idea. When you say solenoid do you mean fuel pump? The line goes from the tank to the filter to the fuel pump to the carb.

Al

The solenoid is part of the carb. When you shut down the genny the solenoid pushes a needle into the main jet to stop gas flow. I guess even when you kill spark the genny can still ignite the fuel and stay running. So they physically plug the main jet.

Cant remember how it works. Would assume it fails to being closed. Maybe its just the electrical connection wiggling around. Gets warm after 30mins or 2 hours and wiggles enough to lose contact. Main jet gets plugged and genny stops.

If that is the case the float bowl should be filled when the genny quits running. See how much gas drains out.

[FLRosebud]

Originally Posted by craigd853

What kind of temperatures outside are we talking about when your generator shuts down? I believe one of the people who respnded explained that you should check the float bowl to see if there is gas in the bowl when this happens. This would definitely tell you rather you have vapor lock or a fuel pump issue. On my onnan 5500 the squirel cage is under the metal cover on the bottom side looking at it from underneath. Not going to swear to it but I believe there should be several small breathing hole and the squirrel cage is right behind this. Sorry I cant be of more help but my onnan is a little bit newer than yours.

Since I'm in FL the temps are always warm to hot. It's been happening at various temps. I've been an engineer in the forensics world for 16 years, so I'm used to root cause investigations, and this one it driving me crazy. The float bowl idea is a good one. I'll have the RV over here in a couple of days prepping for a trip, so I'll do a closer inspection for the squirrel cage and make sure airflow hasn't been impeded. The other thing is I seem to remember (maybe, memory is not as good as it was 20 years ago) is there was a piece of insulation on the gas line a while back when I changed the oil, and before the shop dropped the genny for the spark plug. That is the reason for my question - are your fuel hoses in the genny compartment insulated?

Al

[DeWat]

Someone just described a very similar problem earlier this week. I looked for the thread, but couldn't find it. In their case, their generator kept shutting down while they were driving with a code 36. They checked all the usual culprits, but none fixed the problem. Turned out in their case, the fuel line to the carb was not the right size for the carb barb, and was introducing air into the system while driving. I said this to ask if it is possible when they dropped the generator some to change the plug, could they have partially unseated the fuel line?

[craigd853]

Originally Posted by FLRosebud

Since I'm in FL the temps are always warm to hot. It's been happening at various temps. I've been an engineer in the forensics world for 16 years, so I'm used to root cause investigations, and this one it driving me crazy. The float bowl idea is a good one. I'll have the RV over here in a couple of days prepping for a trip, so I'll do a closer inspection for the squirrel cage and make sure airflow hasn't been impeded. The other thing is I seem to remember (maybe, memory is not as good as it was 20 years ago) is there was a piece of insulation on the gas line a while back when I changed the oil, and before the shop dropped the genny for the spark plug. That is the reason for my question - are your fuel hoses in the genny compartment insulated?

Al

Hello sir, after re reading your first post on this issue and not having this problem until after they changed the plug. It's quite possible that it could be a loose connection because you stated they only dropped the genny a couple of inches to get to the plug. I would call the people you had change the plug and explain whats going on or you could check the fuel pump connections and wiring to make sure there are no loose connections. Also you might want to check the circuit board, flip it over and make sure there are no burn marks on it. I know there is a company that can bench check that for you I'm just not sure of the name. Someone should be along here shortly and can shed some more light on the subject

[donr103]

Here is what I would do.. I would get a can of starting fluid.. and very next time it happens.. I would spray that into air cleaner... use all safety precautions.. and see if it starts.. that would tell you if electrical or fuel.. report back on your results..
Good luck and keep us posted

[tiffy2000]

The electric fuel pumps on these gensets do have a habit of overheating and shutting down. Sometimes the rubber fuel lines can have pinholes which allow it to suck air into the system. I have a 5500 and it doesn't have insulated fuel lines.

[FLRosebud]

Originally Posted by DeWat

Someone just described a very similar problem earlier this week. I looked for the thread, but couldn't find it. In their case, their generator kept shutting down while they were driving with a code 36. They checked all the usual culprits, but none fixed the problem. Turned out in their case, the fuel line to the carb was not the right size for the carb barb, and was introducing air into the system while driving. I said this to ask if it is possible when they dropped the generator some to change the plug, could they have partially unseated the fuel line?

Interesting. Actually, I've been through the fuel line and did all the connections/clamps myself, as I changed the fuel filer twice and the fuel pump once after the problem began. Took 4 months to get the correct fuel pump from Onan. I ordered an aftermarket one, and the end fitting to the carb was oriented wrong, and I wasn't able to make it fit, try as I might. The aftermarket fuel pump was smaller in diameter and lighter than the Onan, so obviously cheaper made. I still have it as a spare, as in a pinch I could certainly use tywraps to secure it for a while.

@craigd853 suggested chatting with the shop. The bad news there is the 2 guys who worked on it have both passed away in the last year, and the shop has a new owner. Oh joy, right?!? At this point maybe I change all the fuel lines and clamps with new, just to be sure. That's a cheap try.

Al

[FLRosebud]

Originally Posted by tiffy2000

The electric fuel pumps on these gensets do have a habit of overheating and shutting down. Sometimes the rubber fuel lines can have pinholes which allow it to suck air into the system. I have a 5500 and it doesn't have insulated fuel lines.

OK, that makes me feel a bit better. I would have hated for it to be something that simple considering what I've done so far....

Al