225 SHO (2015) loss of power/rpms

[utinator]

I have only been out on the water a few times this year, but I have noticed that I can't get the mph or rpms that I was getting last year. Right now, I can only get about 62mph/5200 rpms. I have lost about 10mph/1000 rpms. It's not the HotFoot. The rpms top out before I get the Hot Foot all the way down. The prop is still perfect. The trim maxes out. I run Ring Free, and even added fresh gas. I pulled the spark plugs, and found the lower two plugs to look a little dirty. I changed those two plugs, and it still doesn't run right. I hardly had any tackle in it, so weight is not an issue. The hole-shot seems normal. There is plenty of power in the mid-range too. It just has nothing on the top end. It's like the computer is just stopping it from going any further.

I suspect a fueling issue. I don't have a way to check the fuel psi on the water, but I do have the flow rate on the Lowrance. It maxed out around 21, I think gal. per hr. I don't know what it should be though. Since it's a 2015 motor, it's just out of warranty. I'd like to fix it myself if I can. Has anyone ever heard of an issue like this? Any ideas on what to check?

[Hchamberlin1]

Just because the hot foot is opening fully doesn’t mean the throttle is. I’d get a helper to watch the throttle on the motor and verify it’s opening fulling

[Wackyjig]

Here's what I'd check

1)Pull the cover off and have someone push the hotfoot down all the way. Verify the throttle plate is opening all the way.

2) verify the primer bulb will get firm when pumped

3) Remove and inspect fuel filter element. Might as well replace it while you're there.

4) Check your lower unit gear oil for water intrusion

5) Check engine oil level for made oil or water.

[TexasSkeeter]

I just went through the same problem with my 2020 225 sho on my skeeter zx225. It started acting up and not wanting to achieve full rpms. I took boat to dealer, they ran full diagnostics on outboard, checked and verified throttle cable, and verified engine is at full throttle. I could pop up on plane no problem, midrange was stout, upper rpms (5200-6000 just wasn't there for sustained high rpm operation. At first, the problem was intermittent, and I thought the low pressure lift pump was failing. Dealership said fuel system checked out fine. When outboard would fail to reach 5200-6000, I could pump primer bulb, run like a bat out of hell, then I would lose speed. It ended up being the little valve in the fuel cap. The fuel additives had developed a buildup and wasn't allowing the fuel tank to vent. Take boat out, run it across the lake, take fuel cap off and see if it releases any built up pressure.

[TexasSkeeter]

Dealership told me they have had several fuel systems on new boats that are having problems venting. The 2011 closed fuel system requirements are a pain in the butt. Basically the low pressure lift pumps are pulling a vaccum so hard on the gas tank that due to the tank not venting, and it won't allow air to flow to the fuel system under high fuel demand, or upper rpms for sustained operation. I pulled spark plugs too before, I discovered the fuel cap venting issue, and dealership told me carbon buildup will occur if not able to achieve higher rpms long enough to burn it out. I replaced the lower 2 plugs and everything has been fine. Sorry for long post, but maybe this will help original poster and others. I'm not an outboard technician, just a fireman, who loves to fish

[TexasSkeeter]

Also could be clogged fuel filters, fuel lines, fuel water separator sucking air. I believe, 10-12 psi is what the low lift pump should pull as far as vaccum pressure. Check fuel lines for cracks, tank for debris and fuel tank pickup screen. Also on the 2011 closed fuel system there is a vapor canister that has a check valve on it that sometimes sticks and doesn't allow proper venting of fuel system. Try running boat on a separate fuel tank and see what happens.

[TexasSkeeter]

The fuel tank has to vent and the fuel system should not have any air in the system in order for fuel to be pumped into the filters and finally into the vst, where the high pressure pump delivers fuel to the fuel rail for injectors. Good luck

[utinator]

So basically, I need a new fuel cap? I'll have to order one, I guess.

[utinator]

UPDATE:

I heard about a "gas cap mod" that might fix the gas tank venting problem. I tried this mod, and it seems to be helping. When I take the gas cap off, the tank no longer sucks in air. I can run my boat (ZX225) up to about 5800 rpms and 68 mph with the 4-blade prop that I have on there now. It's only a couple mph and 200 rpms lower than it used to be. BUT.....when I run at that speed/rpm for about 10-20 seconds, the warning horn goes off. I immediately let off the throttle when this happens, and the horn goes off within about 5 seconds.

I still think it's a fueling issue. The gas cap mod is definitely helping. I'm just not sure if it is the only problem. I'm starting to think this is a "boat" issue, and not a "motor" issue. I'll probably start a new thread over on the Skeeter board.