2003 Mercury 200 DFI stalling during midrange RPMs

Hey All,

I was out today and during some light chop while cruising at around 4000 RPMs the engine fell down to 2500 RPMs and then stalled out.
It started right back up and idled fine. While accelerating there was some hesitation and once I got about 4200 it ran fine. Again I came back on the throttle to under 4000 and the same thing happened. The engine again started right back up and idled fine. I was able to cruise back to the dock at close to wide open with no issues. Once I was back inshore, in calm water, I was able to replicate the problem.

While replicating the issue, when I pushed the choke in via the key, the engine maintained whatever rpm I was at.

I thought it was the water seperator, but it had no water in it.
I checked the plugs, all 6 were oily but not fouled.
I use the boat frequently and put non ethanol in it.


Any help to start troubleshooting would be awesome.
Serial on the motor is 0t761047

Your engine is carburated it is not a DFI.

When was the last time the fuel pump was rebuilt?

Thanks for the clarification. I have had the engine for about a year and have not rebuilt the fuel pump. I just looked at the pump and it looks like it was removed at some point but I have no idea.

So this morning I changed out the water separator and inline filter and noticed a small amount of sediment in them. Changed out both and ran the boat for about 100 miles. I could not replicate what happened yesterday but it was like a lake today.

Just rebuilt the fuel pump. The gaskets looked worn and the check valves felt brittle. No debris or build up in the pump itself.