Gunk in Onan Marquis 7000 carb

Dave H M wrote:

96Bounder30E wrote:
I would love to take some of the crud in the picture above and put it in a baby food jar full of Seafoam and seal it up......I wonder what it would look like a week later?

great idea 96, I got the seas foam but not the crud. :h

Anyone have any carburetor Gunk they would like to donate in the name of curiosity?:B

The only new parts I put on the carb was the vacuum line going from the choke diaphram to the carb body. I just took everything apart, cleaned the metal parts in the sonic cleaner, and cleaned the rubber and plastic parts with alcohol/acid brush. I figured if I broke something I would just fork out the $180 for a new carb. I did see a rebuild kit for $80 but for a $100 more buy the new carb. The only thing that didn't do well was the paint on the bowl in the sonic cleaner. It left a funky pattern on it :)

96Bounder30E wrote:
I would love to take some of the crud in the picture above and put it in a baby food jar full of Seafoam and seal it up......I wonder what it would look like a week later?

great idea 96, I got the seas foam but not the crud. :h

I have a friend that works in a parts house, he convinced me to try mechanic in a bottle, I followed the directions and my Onan 4kw gen works fine now, it would not even start prior to this..Wally world stocks Mechanic in a bottle now too.

I would love to take some of the crud in the picture above and put it in a baby food jar full of Seafoam and seal it up......I wonder what it would look like a week later?

New Blue, as far as "rebuilding" the carb, what did you do? When I replaced the carb on our Onan Marquis 7000 there was no bebuild kit. And after taking the old one off I really didn't see anything to do other than an o-ring or two. The carbs on these things in my opinion are pure junk. Went to the Onan shop in Idaho Falls, ID. to get the new carb and when I asked the parts guy if he happened to have that particular carb number in stock his answer was "I better have 3 or 4 of them on the shelf because we go thru them". Sure enough he did. But now the soon to be boat anchor will start 3 out of about 8 times (cold start) as it should. The other times it chokes, pukes, loads up, back fires thru the carb twice after several push on the start button. Usually when a load turns on like the AC, etc. it will fart once or twice then pick up. No smooth transition. While we sit in Yuma for five months it gets started every month and a load put on it for about 30 minutes. I've used regular Sta-bil, Marine Sta-Bil, and Seafoam. Every time I see a Honda or Yamaha genny start I just cringe.

seafoam is good, I use it occasionally. I use stabil everytime I fill. Learned that many yrs ago with a Merc outboard. Expensive repair. I always fill it with stabil added and run it long enough to get fresh fuel to the carb. Done deal, no issues. My 3500w Honda sits for yrs at a time always starts on 2nd or third pull. The Onan always starts.

What you just have on that shop towel is more gelled stuff than I've seen in any carburetor. That must be years of accumulation.

Reddog is right about storage and how fuel (or the lack of it) works. There can be exceptions, though. During one winterization of equipment, I serviced 125 small engines. All had there tanks filled with Stabil mixed into the fuel. The following Spring, all of them started except 12 engines. All of those Kawasaki engines had gelled fuel in the primary jet. It is sometimes how the carburetor is built, particularly, how it is vented. The following year, those Kawasaki engines were stored without fuel and the following Spring, they all started and ran perfectly.

Some of the guys have introduced their SeaFoam (or whatever cleaning agent) into the carb by disconnecting the flex fuel line, letting it drain, and filling it with some cleaner. Then start it, run a minute, shut off to let soak, repeat.
But, you worked a near-miracle once. Why not tear it down and clean it again? I had a gunked-up carb for an ONAN BFA that I couldn't clear out. Had to send it to a shop with ultrasonic and they fixed it. If you already have that technology, go ahead and take another run at it.

I don't think this stuff made it past the fuel filter. The secondary fuel filter has a 12 micron rating. This is gas that gelled in the fuel bowl itself. The genset is on a race hauler (trailer) with a 15 gallon tank. I think my only option is to add Stabil because draining 15 gallons each time would be a pain.