We purchased a small DuroMax Elite MX4500E 4,500 Watt 7 HP OHV 4-Cycle Gas Generator from Amazon in Oct 2012. We have had no problems with it since purchase and have probably 75 hours on it. That is until last weekend. I was using it with our air compressor (as I have for many hours previously) and t started sputtering and coughing and then died. The spark plug cap was shattered and I assumed that it must have gotten bumped and wasn't getting a strong consistent spark. I ordered and replaced the spark plug cap and it fired right up and ran great for about 20 minutes under load then sputtered and died. It fired right up but as soon as I put any load (from air compressor to skillsaw and even a small lamp) it sputtered and if I kept the load on it it would die, if I turned the load off, it leveled right back out and ran fine.


Everything I have read states carburetor issues but I don't think that this is it, I suspect something with the windings or the actual electricity generating rather than the motor itself. Any thoughts before I either tear this thing apart or take it in for service? Thanks!


Jamison

What happens if you manually hold the throttle open when the generator is under load?

Check the high speed rpms , and make sure its running at max , speed,
But its on the engine side not the generator.
It does sound like carb trouble.

Thanks for the feedback thus far! I went out in between rain showers yesterday and was able to test some more. The genny fires right up and runs perfect under high load for about 10 minutes and then starts to bog and sputter. There is about 3/4 tank of gas in the machine. I suspect that my recent gas fill might have had some water or particulate in it and it takes some time for it to settle down and affect the carb. Does this make sense? You would think that after sitting for a couple of days any particulate would be on the bottom of the tank and get immediately sucked into the carb and prevent the engine from operating smoothly or even starting easily. Maybe more inclined to think water and the vibration of the genny makes it mix up and then becomes a problem?I am planning on shaking up good and draining some gas to see if water settles out. Any other thoughts?Thanks again!Jamison

Is there a vent on the gas filler cap? It sounds like you are losing fuel after it runs a bit. A bad vent on the cap could cause this.

Is there a vent on the gas filler cap? It sounds like you are losing fuel after it runs a bit. A bad vent on the cap could cause this.

Nothing apparent like on my larger generator where there is an actual threaded pressure relief valve. Maybe I will run it for a while this afternoon and open the gas cap see if it makes any difference.

I have a smaller generator that has a cap that doesn't look like it's vented but it is. Just be careful if you open or loosen the cap while it is running.

I have a smaller generator that has a cap that doesn't look like it's vented but it is. Just be careful if you open or loosen the cap while it is running.

Thanks, will do.