New Old Stock Coleman Powermate Generator - Sputter/Miss - already tried new carb..

peteclark3 said:

Hey folks!

My son and I recently purchased a new-in-box Coleman Powermate 6250 generator. We were looking for a good, reliable generator for which we could actually find parts... this one being new in the box, garage kept for its 12+ years seemed like a good bet. Pics attached.

Upon trying to run the generator for the first time, it seems that unfortunately the years of being in the box weren't very kind to the carb. Gas immediately leaked right out of the air cleaner due to a stuck float. We unenthusiastically took the carb apart to free the float, only to see some rust / etc gathered at the bottom of the bowl; I assume due to condensation due to temperature change over the years. We did a quick clean of the carb, started it up, and it ran, but sputtered a bit, when not under load. Under load it ran a bit better, but there was still a bit of a sputter.

Soooooo... we ordered an aftermarket carb to replace it entirely, to eliminate that entirely (since every search on the topic said "carb issues")... installed the new carb, fired it up, and... the sputtering still happened. (Note, this is with a brand new spark plug too - not the one that came with it... the engine sounds the same with both, but we kept the new one in anyway).

Back to the old carb, I chem dipped it over night (removing gaskets/nonmetal items of course) and sprayed it super crystal clean this morning with carb cleaner.. the complex gasket in there still looked good and flexible. Put the carb back on, fired it up, and it still sputters... the video below is the sound it makes as of right now (taken just 10 minutes ago). Still, under load it runs a bit better, but still sputters occasionally..

It's not "intolerable" but we really would like it to run evenly when not under load, because it does exhibit similar symptoms when under load, occasionally.

At this point I'd take it somewhere, but wanted to check here first, because I tend to think they will just tell me "that's how it sounds when not under load" but I've seen YouTube videos of this very generator running when not under load, and it doesn't sputter.

Note that we of course run it with non-ethanol gas, and it truly had never been run before, the tape was original on the box, no tears, not re-taped, had no oil in it, etc.

At this point I wonder if it is something electrical... faulty low oil sensor? Needs a new magneto (I know this is rare)... ? I'm sort of getting into uncharted territory for myself here.

Thank you for any help you can provide, and if more information is needed, please let me know!

Pete

Video of the sputter: https://www.youtube.com/watch?v=7-ZAmRfCGsE

Photos with engine model numbers and such:

View attachment 34353View attachment 34354View attachment 34355View attachment 34356View attachment 34357

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Robsinno1 said:

I have the same generator and the same problem, but I have the Suburu engine. Just installed a new carburetor, fuel line, inline fuel filter, air filter, and spark plug. I also drained the tank and filled with about a gallon or so of fresh fuel....STILL SPUTTERS! Wondering if you found a solution.

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Boudreaux In Eunice La. said:

How expensive was the carb ???? OEM or ebay chinese ??

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sgkent said:

for me, the weird running issues with many of these small engines usually comes down to a degraded fuel pump diaphragm. Once they leak a little at the valve flaps the mixture is all over the place unless the engine is near full power. I put a new diaphragm in and the device will run like a champ for six months to a year, maybe 2, then the weirdness starts again depending on the design.

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Robsinno1 said:

Carburetor was $24 (not OEM...see attached photos), but I have the same problem I had before changing the old carburetor. The generator is 12 years old and I've had similar problems over the years, which I usually fixed by cleaning the carburetor and spark plug and changing the fuel. I did notice that the new carburetor looks a little different than the original on the air filter side [could not find an OEM (part #279-62304-40); only thing available is a replacement for OEM (Mikuni RGX4800)]. I also noticed a small deformity (gouge) in the intake gasket, which I had every intention of changing, but the gasket that came with the new carburetor wasn't the same. It really didn't look that bad though, and I'm doubtful about that being the problem.

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