Community Forums

Sixgunz · 08-23-2007, 11:15 PM

Check the output "brushes" on your unit. I truly have no idea what they do, but on our 5500 Marquis Gold, they have failed and, from what our RV repair guy tells us, is a common occurrance. Apparently, they get dirty and don't allow the output voltage to exit the unit.

bowats · 08-24-2007, 07:32 AM

Sixgunz, did they have to remove the genset from your camper before replacing the brushes? I am getting fault code 27 which indicates no AC output. Thanks for any more info.

Sixgunz · 08-24-2007, 11:09 PM

No, in fact, it's only around a 5 minute fix. Apparently, these brushes are on the right side & are very easy to clean. Basically, you remove the cover & either remove the brushed & blow them out with air or just blow air through where they sit.

Sixgunz · 08-24-2007, 11:22 PM

On a different note...there are mulitple "jets" in your carburetor which function for various throttle levels.

If you're getting output voltage (and if it's running for 20 seconds, your'e getting output voltage), a jet has gotten clogged from (in my opinion) carmelized gas, which is prohibiting the genny from running at a certain RPM because the jet for that range is completely clogged. It's not a hard fix, but you need to know Onan carbs. You're basically taking the carb off & cleaning out 1 jet.

On a motorcycle or ATV this jet (which is believe could be at fault) is called the "pilot" jet. I have no idea what it's called on a generator, but pilot jets usually have extrordinary small holes (a sewing needle will not go through) & they get clogged easily. This usually occurs when gas in the genny fuel lines sits for long periods of time because there's gas also in the jets of the carb. and carmelize (basically solidify) where it is, thereby blocking & clogging the jet. This is why it is important to run your genny everynow & then, so the gas gets circulated (not to mention lubricate the internal components of the gen with oil).

Fuel stabilizer will extend the period you can go without running your gen (it helps prohibit the carmelization of gas), but don't compeletely rely on it.

peter griffin · 08-25-2007, 04:06 PM

on many new onans the fuels filters 2 dry out. Replace both and plugs check oil, make sure you have enough gas in chassis tank and then start playing with adjustments...

Good Luck...

bowats · 08-26-2007, 11:14 AM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Sixgunz:
No, in fact, it's only around a 5 minute fix. Apparently, these brushes are on the right side & are very easy to clean. Basically, you remove the cover & either remove the brushed & blow them out with air or just blow air through where they sit. </div></BLOCKQUOTE>
Sixgunz thanks. Pulled the brush block cleaned with contact cleaner and blew out everything else. Problem gone. I appreciate your comments as they saved me a trip to the shop.

jrnutpaul · 09-06-2007, 03:08 AM

The generator runs OK now.
I had to replace the battery negative lead because of corrosion and it fixed the generator running problem.

Of course a new air filter,oil filter,fuel filter,plugs,oil,sea foam cleaning and valve removal and soaking didn't hurt either.
Thanks for all the suggestions and help,

Paul

hotrod 32 · 09-06-2007, 11:59 AM

I had a similar situation with an Onan running like you describe. The owners manual said to cycle the switches on the side of the generator off and on. I did this and mine was fine. It was hard to believe because I would have sworn it was a dirty filter starving for gas situation but this cycling worked for me.

Sixgunz · 12-17-2007, 09:25 AM

Since my original post, I have found, and cleaned, the brush block twice on my Onan 5500. The gen will start, then run for between 5 and 20 seconds, then shut off. The light (on the gen & on the switch) flashed three times in sequence.

The brush block on the 5500 is on the upper left side, if looking at it from the front. It's in the rear of the unit & sits on top of a domed, vented metal thingie (the stator housing). The brush block is held on with 1 10mm screw. The part of the block you can see has two wires attached to two spade terminals on the back of the block. The rear of the block is around 1 1/2" square (the part you can see).

With the generator off, unscrew the 10mm screw (be careful it doesn't drop down-it takes a magnet to retrieve it). The brush block then simply pulls away from the stator housing. At some point, you have to pull off the two wires from the spade terminals.

The two brushes are spring-loaded in two form-fitting chambers (lightly loaded) and look like two magnets, 1/2" x 1/8" by 1". They won't come out of the block. Once the block is out, clean it off with contact cleaner & wipe the surfaces with clean cloth or paper towell. Then blow out the stator (with air) where the block was inserted. Viola...reverse instructions to put the block back in.

I don't think any of this is redundant, but if it is, I apologize in advance. It's so easy to do & so common, I wanted everyone else to know about it.

gunny · 12-17-2007, 12:51 PM

<BLOCKQUOTE class="ip-ubbcode-quote"><div class="ip-ubbcode-quote-title">quote:</div><div class="ip-ubbcode-quote-content">Originally posted by Sixgunz:
Since my original post, I have found, and cleaned, the brush block twice on my Onan 5500. The gen will start, then run for between 5 and 20 seconds, then shut off. The light (on the gen & on the switch) flashed three times in sequence.

The two brushes are spring-loaded in two form-fitting chambers (lightly loaded) and look like two magnets, 1/2" x 1/8" by 1". They won't come out of the block. </div></BLOCKQUOTE>

3 flashes indicate that there is another code, read your servce manual to get to it and see what it is.

Brushes can be replaced in the brush holder.

Had a customer who dropped one of the screws, went to the store and got another rather than fishing out the one he dropped. It ran about a week and then the smoke came out. That magic smoke that makes generators work, once gone, they no longer make voltage. New stator for a 6,5 NH, a new bearing, labor to remove the genset, dissasemble (this thing has had numerous salt water baths from road spray in the winter so corrosion was an issue) ended up costing just over $2,200.00

Sounds like you are a mechanically inclined involved genset owner. Folks like you end up being the ones who get to brag about how many thousands of hours they have on their machine. A little maintenance goes a long way.

Sixgunz · 12-17-2007, 11:50 PM

As I recall, the first time this happened to me, I looked up that light flashing sequence & it meant there was no output voltage, which was due to a lack of a clean contact between the stator & the brush surfaces...I'll recheck it though to be certain.