2005 utopia 200hp merc will not go over 3500 rpm

[Carlhere]

Folks
Could really use some help. My 2005 Utopia 200hp merc efi m2 I think it says on there. It sat for about 2 years. The other day went for a ride and the engine sounds like it want to shut down or starving for fuel. It will just barely come up on plane. If you apply full throttle from a stop it will rev up completely and in 3 seconds later it want shut down or sounds like it is breaking up. I have replaced all the fuel after draing the tank completely and used fresh fuel. I have installed new spark plugs and fuel/water seperator. I have check the fuel pressure and air pressure at the injector rail giving me about 80 psi fuel and just about equal for the air pressure. The pressure seems to hold when attempting to raise the rpm and remains at this pressure even when the engine starts to act up about 3500 or a little more. The engine starts with no problem, idles with no problem and runs very smooth unless trying to go about 3500 or above. A mechanic attached a computer to the engine. It has 123 hours and he checked all the cylinders to confirm they were firing and said all was good. It feels like a starvation of fuel. Maybe i'm wrong and its an ignition problem.
But i would appreciate anyones input or if anyone experienced this sort of issue with some feedback
Thanks Carl

 

[Dr Honda]

When you checked the air an fuel pressure... was that with a load? Or... I should say... did you check the pressure when the engine was trying to die?

The ignition doesn't normally fade like that. It's more common to be a fuel issue when it drops off.

 

[Carlhere]

The pressure of fuel and air was check at the dock at about 1200 rpms . The guages were fluxuating/needles between about 70 and 85. We moved away from my dock on the lake and started more rpm the needles started to be steady at about 80 psi for fuel and air nearing about 3000 rpm. We started hitting about 3500 rpm and the engine started to loose power and cutting on and off like is was starving for fuel. The unusual thing is the air and fuel pressure stayed up there. Additional thing I want to post here is that I also checked the charging system and that is about 14 volts.

 

[bhatch21]

Could it be the Mercury Throttle Guardian system limiting the spark? I think it's supposed to kick in around 2500rpm, but if's it's going bad you never know what it may do. Dr. Honda can tell you which wire to disconnect to disable it.

 

[Carlhere]

Hopefully Dr Honda will see this thread and could explain how to disable the Mercury Throttle Guardian system

 

[Dr Honda]

Nope....

I SEE NOTHING !!



LOL.. (sorry)


I was just thinking of that myself.

The throttle guardian is a device to keep the engine from reving too high in reverse, and neutral. It also put's the engine into "Limp Mode". AND.... it's known to fail, and cause issues. (FYI, mine is disconnected)


It's not on any of the wireing diagrams... so it's a "Hidden" device. But... if you look into the helm... you will find a little black box. One of the wires is black with a yellow trace... and it will connect with the kill lanyard, or into the key switch. Disconnect it, and go for a ride.

 

[Carlhere]

Good Morning Dr Honda
I have went into the helm. There were 2 wires on the lanyard so it was not there. Anyway I have had the lanyard disconnected for years. I looked onto the ignition switch. I have found the black wire with the yellow trace but have not found any kind of black box connected to it following the harness as far as I can. Anyway I have cut the wire about 6 inches from the ignition switch. I started up and went for a ride and had the same issue as before. Just a note.....there is also a yellow wire with a black trace connected to the ignition swich. Is it possible that would be the one I should have cut? Is cutting the wire 6 inces from the ignition switch sufficient? Or must I find this black box that I dont see in the helm anywhere?
I want to give you some additional input. Or the dash board fuel guage there is a red light with a little oil can next to it. For years the light did not work. Yesterday I found a ground wire with a heat shrink kind of hanging below the starter on that side. These wires branch off to the oil reservoir sendinding unit on top. They also have a blue wire that goes to each side of the fuel injector rails.
So here whats happening. I found a fault under the heat shrink and the ground did not connect from one side to the other. I corrected the problem.....Now the oil light lights up on the dash board the way it should when you turn the key. But the red light does not shut off even after starting the engine. I have by passed the sending unit on top of the oil reservoir and the light continues to stay on. Is there anything else that would keep the light on and give this warning?? I have also by passed the sender at the bottom of the fuel/water seperator.
Still cannot go over 3500 rpm and have the same issues
Any thoughts?

 

[Dr Honda]

NO DO NOT DISCONNECT IT FROM THE IGNITION SWITCH !! That allows the CDI to drain down, when the ignition is shut off.


You need to find the Guardian. If that's the problem... and it's still hooked up... then cutting the wire at the key won't make a diff. (Unless it was removed by the previous owner)



OK... Just to make sure... do you have the optimax engine? That would be a DFI, not an EFI. I just want to know, so I know what manual to look at.

 

[Carlhere]

Hi Dr Honda
This is a 200hp Optimax Jet drive seadoo. On the air cover it also M2. Cant find anywhere anything saying DFI or EFI
I am the original owner of the boat and never had a guardian removed. I check as far as I can see inside the helm until the wires disappear in the gunnel. I cannot find this black box you're referring too.
I will reconnect the black wire with the yellow trace.
Also the red light continues to be on inside the fuel guage next to the oil can .
Just to re-update the engine does not shut off after 3500 rpm and runs smooth upto that point until I reach 3500 rpm. after that it starts breaking up and the rpm drops like its running out of fuel. If I pull the throttle back to 3500 0r below there is no issue

 

[Dr Honda]

OK...... So, you just stated your real problem. With the oil light on... and the "Stuttering" after 3500 RPM....


The engine is in limp mode. (since it's an optimax)


Figure out why the light is on, and your RPM will come back