This is a brand new MC 383 with about 22 hours... In the break in period I have run the motor passed 4000 rpms with no problem.

Last weekend while out I ran it up from idle to 4k the motor pulled strong all the way then a 4k it started popping. It sounded like a hi speed lean out and not a rev limiter sound. I tried it a few more times during the weekend and same thing every time.

We were on a trip so when running at 27-32 rpm the thing ran great no bells or whistles going off. All systems checked out. However every time I took it up at 4k pop pop and then I had to back down.

Today I pulled the water sep filter and the gas was real clean and no sediment.

Any thoughts? Thanks in advance!

fuel pump?

You need to hook up a fuel pressure gauge, a Snap on, type. If the fuel pressure is dropping off and this is a new package someone did not pre fill the filter with fuel. That should be in the canister which holds the fuel pump also.

I guess I don't understand your reply...for the 1st 20 hours I could run this thing up to redline. No problems...now it still pulls strong until 4000 rpm. So would not the problem show up before?

Your fuel pump might have been fine before. SOMETHING is not right now since you have a problem NOW. Just because it worked yesterday doesn't mean it is working today. Hook up a fuel pressure gauge and see if the pressure( fuel delivery) is keeping up.

Don't get me wrong I was not questioning the fuel pressure gauge hook up... it was the part that it was not pre filled, and that would that take 20 hours before something would show up.

Hooking up a FPG makes a good first choice.

Once the pump gets damaged, it will start dropping fuel pressure down to the point you have now. My point of using a gauge, is to keep it simple. You have a fuel issue from what you stated, so start with that. This my not be the issue, if not the pump has been eliminated.

Heck of a deal...picked up from Auto Zone a FPG testing kit. Just put a deposit down and when I return the kit, I get all the deposit back. Tomorrow we will try it out and see what gives.

Ok good luck!

Did the fgp thing today and everything is OK and within specs. Pulled all plugs just in case a plug was bad. They all looked good, same grey tan color. ??? Now I am wondering if it is time to take it in and let them do the hunting down of the problem.