2000 50HP 4 Stroke - Reving Problem

[rickwoz]

Hello All,

When I start my motor it starts to over-rev immediately. No idle, just keeps hitting the over-rev limit. The throttle is at minimum speed position.
Any suggestions ???

Thank you and Happy New year !
Rick

[Harper]

Well, I gather from reading your other posts on this same subject that this has been going on for two years now? Or has not been going on, but the motor has again sat unused for two years?

Have you actually looked at the throttle body to see the position of the throttle plate, to see if it's stuck open? The parts diagram isn't clear about whether there's an IAC integral to the throttle body, and it's impossible for the motor to rev to limit without some source of extra air getting through the intake. It doesn't take a huge opening in the throttle body or elsewhere, since there's no load in the engine, but there has to be some way for intake air to be getting in besides a properly positoned throttle plate.

So check for any large vacuum leaks, damaged or disconnected vacuum hoses, check the throttle plate opening, etc, and get back to us. Don't wait two years this time to respond to suggestions.

[rickwoz]

Hello,

I'm back.
Just replaced the fuel vapor separator and injectors. All new.
Start the engine and it revs to 3k then back down a little over and over.
Throttle is all the way back to neutral,position. It should be idling. Now what ??
What controls the rpm in this engine ? I have a video of what is happening, but it's not hard to understand what
my problem is.

Thank you.
Rick

[Moonlighter]

IAC valve.

IAC stands for Idle Air Control.

From that name, can you guess what it does?

It is the thing that controls the engine at idle speed. Many, many engines in cars etc use an IAC valve for this role. Google and you will find out much more info about IAC valves.

It seems likely that the IAC on your engine has failed. The symptoms you described are typical. Often that is accompanied by a fault code. But not always.

If I recall correctly, these are made for Suzuki by Mitsubishi. Locate the part on the engine and see if you can find a part number on it.

You then have 2 options, to buy the genuine Suzuki marine part, or to use that stamped on part number to source a quality Mitsubishi part from a Mitsubishi car dealer with the same part number. Some people have used aftermarket no-name IAC valves but they seem less reliable, but are cheap. Some parts suppliers will supply the Mitsi branded parts too because they fit multiple brand cars.

If you go to the top of this forum and click on the “Buy Suzuki Parts” and then, using your engine details, you will be able to locate your engine and find the genuine part required.

[rickwoz]

Problem SOLVED !!!

I'm an idiot !!!
A hose way down in front of and under the 'separator' was NOT connected.
Figured it out by reviewing sensor descriptions in service manual.

Thank you everyone for your responses.
Rick