Genset Surging Code 14

Dustdevil · 10-02-2016, 07:57 PM

Seneca has a Quiet Diesel QD5500 on board. Took a day trip yesterday to the lake, and the generator started fine, but after 5-10 minutes it started surging, then 5 minutes later it just shut down. My message panel isn't displaying messages now, so I had to rely on the Onan codes to figure out why it was shutting down. It was Code 14, which is over-frequency. This indicates it's running fast, but it was actually momentarily sputtering, then speeding back up, and I think maybe even over-speeding a bit when it would catch back up. Looks like the over-speed sensor was the first to trigger the shutdown.

I read up on it, but most of what I was finding had to do with gas generators, and most of the problems seemed to be with the carburetor varnishing up. Since the diesel doesn't have a carb, I pretty much knew that wasn't it. Besides it sounded a bit like it was starving for fuel, then catching back up when enough fuel would trickle through to let it run properly for a few seconds, before stumbling again. I suspected a fuel filter clog.

So, I took a chance and picked up a new fuel filter, and changed it out. Sputtered for about 15 or 20 seconds, then smoothed right out and purred like a kitten. Ran it for an hour or two with the AC running to provide a load, and it ran perfectly. It's got maybe 150 hours since the last fuel filter change. It's a short shift for what was a new filter 150 hours ago, but I'd much rather this than dirty fuel clogging fuel injectors and wearing out the pump.

Just wanted to post this for anyone running into this problem and wondering where to start to troubleshoot the thing. I'm about due for an oil change also, and I'll get that done in the next week or so as well, once I can find an Onan oil filter and a new air filter as well. Hope this helps someone down the road who may need it.

abarkl · 10-02-2016, 08:42 PM

We had the Onan Marquis Gold 5500 gas for 10 years in our first motorhome and whether it was a failing fuel pump when it was hot (known problem with the Onan gas fuel pumps) causing surging, or from lack of use or the recommended monthly exercise of two hours with a 50% load, we had to replace the carburetor twice when it became gummed with varnished fuel.
Our last two motorhomes have had the Quiet Diesel and they seem to be a little more forgiving.
If it could always just be so obvious and a simple fuel filter change.

Dustdevil · 10-02-2016, 09:43 PM

Yeah, I got off easy this time. Although, I do think the diesels have fewer potential problems, at least in theory. No ignition issues, no carb. Little to no varnish.

mike837go · 10-03-2016, 06:01 AM

Quote:

Originally Posted by Dustdevil

Seneca has a Quiet Diesel QD5500 on board. ...snip...

So, I took a chance and picked up a new fuel filter, and changed it out. Sputtered for about 15 or 20 seconds, then smoothed right out and purred like a kitten. Ran it for an hour or two with the AC running to provide a load, and it ran perfectly. It's got maybe 150 hours since the last fuel filter change. It's a short shift for what was a new filter 150 hours ago, but I'd much rather this than dirty fuel clogging fuel injectors and wearing out the pump.

Just wanted to post this for anyone running into this problem and wondering where to start to troubleshoot the thing. I'm about due for an oil change also, and I'll get that done in the next week or so as well, once I can find an Onan oil filter and a new air filter as well. Hope this helps someone down the road who may need it.

Yeah, Diesel fuel is like that. One bad load or some water and you're out a filter.

Helps to keep a set of spares on hand and the tool(s) to swap 'em out.

Dustdevil · 10-03-2016, 07:43 AM

Quote:

Originally Posted by mike837go

Yeah, Diesel fuel is like that. One bad load or some water and you're out a filter.

Helps to keep a set of spares on hand and the tool(s) to swap 'em out.

I was thinking this morning that it wouldn't be a bad idea to go ahead and buy my next spares right now and just keep them in the motorhome. Rotate them in next year, and then buy new emergency spares at that time.

Oh, and diesel fuel is notoriously dirty. So a bad load of fuel can either disable the injection system or the filter. I'd much rather it clog a filter than wreck the whole system.

mike837go · 10-03-2016, 08:05 AM

Quote:

Originally Posted by Dustdevil

...snip...
Oh, and diesel fuel is notoriously dirty. So a bad load of fuel can either disable the injection system or the filter. I'd much rather it clog a filter than wreck the whole system.

That's the whole idea!

The ULS I've been buying for my daily driver (the station serves OTR trucks too) has been very clean and dry. Almost nothing in the can when I swap elements every 20,000 miles.

The #2 I use in the tractors.... YUK!!! Too many hikes back from the field! and 1 no-start. In 2015 I rigged the pump to draw 4" off the bottom of the tank and there is a visible filter With a drainable water trap between the pump and hose. No fuel issues since then! (spare element and wrench on the windowsill 15' from the tank)

Dustdevil · 10-03-2016, 08:27 AM

For sure. I had a Chevy pickup with a Duramax for 13 years, and the OEM fuel filter was the next best thing to useless. Best thing I did was purchase a kit with a 2 micron Cat filter as an auxiliary. It was large enough it only needed to be replaced once or twice a year. But it was an absolute filter, where everything 2 microns or larger was removed. I'm a believer in filtration, and that especially includes the high pressure fuel systems in the modern diesels. Went out of my way to get the OE on the Onan, though. Some reviews seemed to suggest they were really the best choice.

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