Hi. I really hope someone can help me with this problem - we haven't been able to enjoy our boat all summer.
This is our first boat. A 2000 Princecraft Vantage pontoon boat, with a 2000 40HP Evinrude 4-stroke outboard motor. Rebuilt by the previous owner about 5 years ago.
The motor starts fine and runs great... until I throttle up to 3000 RPM. At that point the engine surges back and forth, about twice per second, with the RPM dial swinging back and forth between about 2000 and 4000 RPM.
This only happens when it's in gear. In neutral it runs just great up to at least 6000RPM.
The whole scenario is absolutely, perfectly repeatable. It's almost exactly 3000RPM every time. Every day, every week. And it runs fine in neutral, every time.
The water is flowing through the motor just fine, the prop is not fouled with weeds or anything. That just about completes my diagnostic abilities. I have changed out the fuel filter but that was before I realized how great it runs in neutral.
So here's why I can't easily take it to a certified Evinrude mechanic: The only such mechanic in our area is inland - off the water. And I lack a truck or trailer or the ability to pull my motor and transport it. My friendly neighborhood NON-Evinrude shop has offered to pull the boat out, pull the motor off, and transport it to the Evinrude shop - for a few hours labor each way, and when they can find time for it, which never seems to be now.
So ideally I am looking for information to give him, the (really nice) shop owner who does the best he can with my Evinrude.
09-06-2016 11:57 - edited 09-07-2016 07:18
Please do not race the motor in neutral. In some cases the internal engine parts could suddenly become external engine parts.
If there are Suzuki technicians available, they could service your motor as that particular 4-stroke Evinrude outboard was built by Suzuki.
Your description sounds like it has a fuel delivery problem. It could be in the boat's plumbing due to some type of restriction or air leak or it could be due to the high pressure pump or partially clogged injectors not being able to flow enough fuel to the cylinders. Plugged up fuel filters could also give similar symptoms as well has a restricted fuel pump screen. A knowledgeable tech can troubleshoot your motor to determine if the problem is fuel related or if it is mechanical or electrical.
There is no "load" on the engine when you rev it up in neutral so it does not need much fuel. In the water while pushing a heavy boat, the motor needs significantly more fuel to generate more horsepower to turn a propeller several thousand rpm to move a boat.