2011 df225

[chasenfins]

Ok, about stumped. So coming in from 40 miles offshore Sunday about 3 to go before I hit the inlet the engine would reduce from 4000 rpms to 2800-3000 when the bow would hit the back of a small 2' wave. I've never had the engine reduce rpms that drastically on a load. So got home, checked fuel filters, all clear. Drained vst into a clear container and fuel looks and smells great, free and clear from debris and water. Hooked up the inline fuel pressure gauge and have 36psi at key on and maintain while running. Key off fuel pressure drop test was good staying well above the minimum 25psi in 5 minutes (so no leaking bushing on the hp pump). Pulled spark plugs and though they looked slightly worn they didn't look too bad, but replaced anyways since I was there.

Anyone got any ideas what else could cause that? Gonna power trial Wednesday but I'm not convinced that the plugs were the problem though everything else checked out.

[artdf175]

almost sounds like a sensor is faulty or loose wiring that is causing the engine to temporarily go into a safe mode condition
I assume no alarms sounded
to be safe have a dealer scan your engine for fault errors, if any errors they should show up here

ok here is one more thing to check - read sticky I posted on the "white wire" situation
any interruption in voltage to the ECM creates a big problem in a hurry
check all power connections Suggest starting at the battery the secondly the white wire
Art

[chasenfins]

No, no alarms. I checked battery cables at both ends, they're tight. Thought about the white wire issue but didn't lose anything on the dash or actual power. I'll double check it though just to rule it out. The sensor theory is what I was leaning towards but with so many and not having SDS yet just about impossible to diagnose. Besides oil pressure, what other sensors cut speed back for safety?

[Murray]

Check out the sticky at the top of the page.

http://www.suzukioutboardforum.com/f...agnostic-codes

[chasenfins]

There's no check engine light, or any blinks. Once I get SDS I plan on checking for any inactive faults, maybe something tripped a code real quick but no lights have been on while running it.

[artdf175]

I don't have the manual for your engine
but if I remember correctly there are a couple of faults that don't trigger a code that will put the engine into safe mode

[chasenfins]

So here's an update. Found the fuel fill hose was destroyed thanks to Sea Hunt and their rigging. The foam in the hull was compacted on it and the chemicals in the foam counter with the hose. So fixed that.... new fill and vent hoses. Went out on a test run and AGAIN....5200 cruising for about 10 minutes and bam! RPM dropped back to 2800, fuel priming bulb never went soft and no faults. It fills like its losing fuel. Bought a few adapters and checked the hp pump, it's all in spec. Can't find a test procedure for the low pressure pump. Any one know one? Crazy thing is I don't think it is the LP only because the engine idles and trolls fine, doesn't miss a beat. But need to rule it out.

[artdf175]

did you happen to look at the inline fuel filter pre LP pump?
It should be full and no air

[chasenfins]

Not while running. It was full when I removed the VST this past weekend. But when the SDS software gets here the week, I'm gonna hook up the laptop and run it with the cover off and I'll watch for that. Gonna take a small portable tank and run off it one trip too and see if the different hose and tank makes a difference as well. Something has to give, watch it be something small and stupid.

[artdf175]

The reason I ask is because I recently had a problem of running along a bump a wave and engine cut back from over 4000rpm to 4000 - back off and run back and would kind of lug down and not go over 4000.. until I turned it off a restarted. would then run ok for a bit until another bump . repeat
I went through all connections thinking it was a wiring problem. Then noticed fuel filter was only half full. after replacing the water/fuel filter and various other parts of fuel hoses -- found the fuel bulb was leaking air. replaced it and problem solved.
have no clue why the 4000 rpm limit, maybe that was all the fuel the engine could get to run, but then again, why would it run normal for some period after restarting?
your comment about the engine dropping back after bumping a wave sounded like my problem to some degree.
Art