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

#1

P

peteclark3

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:

IMG_0615.jpgIMG_5041.jpgIMG_2051.jpgIMG_9310.jpgIMG_0142.jpg


#2

I

ILENGINE

Sounds like a slight misfire. Could be inherent misfire of the spark plug. Could be ignition module, Could be fuel related. Could even be a slightly sticky valve resulting in that sputter.


#3

Boudreaux In Eunice La.

Boudreaux In Eunice La.

I would run it on a load for a while to see if something is plugged somewhere. I know you said it was new, but maybe something in the fitting on the tank or a screen in the tank.

Maybe just try and move the govenor arm by hand a few times to see if it's not sticking a lil bit ~!~!

Hope this helps Mon Ami ~!~!


#4

R

Robsinno1

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
Click to expand...

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.


#5

Boudreaux In Eunice La.

Boudreaux In Eunice La.

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.
Click to expand...
How expensive was the carb ???? OEM or ebay chinese ??


#6

Boobala

Boobala

I have the same Gen. but with a 10 HP Tecumseh, and it sounds exactly like yours, even sputters a lil bit more BUT I have no problems with mine, it performs as it should, try running it with a load on it for awhile, plug in a medium wattage elect. space heater (1500-1750 W.) and see if it smooths out after 10-15 min run time... as long as it's putting out I wouldn't be too concerned, I often think its the Gen. itself creating a varying load output ...???? .. I've had mine for 6 yrs now gets used every year during Hurricane season :thumbsup:

ebay117.jpg...ebay119.jpg


#7

R

Robsinno1

Boudreaux In Eunice La. said:
How expensive was the carb ???? OEM or ebay chinese ??
Click to expand...

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.

Attachments







#8

sgkent

sgkent

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.


#9

R

Robsinno1

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.
Click to expand...

Thanks for your advice, unfortunately this generator's carburetor is gravity fed; there is no fuel pump.


#10

Boudreaux In Eunice La.

Boudreaux In Eunice La.

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.
Click to expand...

Gaskets have to be just right..... especially if there is a vent hole or a hole for a primer system style carb.. Yes I make my own larger gaskets and some small carbs also but if they have the holes in them I buy them from my distibuter in 10 packs..... Not worth the hassle....

If you got a cheapo carb and it came with the wrong gasket then the carb just might not be the one you need for your engine .... Just a thought.......

Try what Boo Boo said and 1 more guy said and run it with something that will pull a good load on the Genny ......

Let us know Mon Ami ....


#11

Boudreaux In Eunice La.

Boudreaux In Eunice La.

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.
Click to expand...

I see 2 different carbs in the pictures... Original one is on the left and new on the right... Look at the bowl vent on the old one...... Way different than the new carb..........


#12

sgkent

sgkent

many think these carbs are gravity fed but if one looks closely they will often find a diaphragm or series of channels that use the pulses between strokes to pump fuel into the stream or bowl. Also places carbs like this can fail are some carbs have set metering to comply with EPA and CA-ARB standards. If those are loose or tightened too much it can crush the metering jet tips into the passage. Also I found one article on that engine on a generator where someone found that if the air cleaner bolts are over tightened it causes issues like that. Good luck finding the cause - hope you resolve it.


#13

Boobala

Boobala

IF... you're interested, you can find a boatload of carburetor info in these videos, as well as a myriad of other small engine operating items.......

https://www.youtube.com/user/TheRepairSpecialist/videos


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