Sputtering Suzuki 2004 140HP four stroke

I have twin 140HP Suzuki 4 four stroke engines one runs greats the other started sputtering in and out at wide open throttle a couple of weeks ago and now it is doing it at lower RPM ranges. Both the engine are running from the same fuel tank. When I first started having this problem I fiqured it was a fuel filter problem so I replaced the Racor filters and still had the problem. Decided to replace the low pressure filter and high pressure filter still have the problem. I boat the boat used in VA last winter and they had not yet switched over to E10 fuel down there, and when I brought the boat back up to NJ it got fuel with ethanol. When I replaced the Racor filters there was a lot sediment in the bowl. Today I brought the engine up to about 2500 rpm and it was surging between about 1800 rpm to 2500 rpm. Anybody have any suggestions on what to check next?

Re: Sputtering Suzuki 2004 140HP four stroke

There is a filter on the bottom of the fuel pump in the VST tank.
There are screens on the fuel injectors.
Drain the fuel rail and VST.
There is a high pressure fuel filter
There is a low pressure fuel filter
Boat fuel filter.

If you have Phase Seperation in your fuel double check your "new" filters.

Re: Sputtering Suzuki 2004 140HP four stroke

I will try that when I get back down to the boat one night this week. I don't think I have phase seperation of the fuel, if that was the case I would be having problems with both engines. There was not any sign of water in the fuel when I drained the Racor filters. Somebody also mentioned I might have a sticking antisyphon valve on the tank, I am going to switch the fuel supple lines to the opposite engines at the primer bulbs to try and help narrow down where the problem is. I am thinking by switching the lines if the problem shifts to the other engine it is a sticking antisyphon vavle or something between the primer bulb and the tank. If the problems stays with the orignal engine having the problem it is something after the primer bulb or in the engine.