Answer
Jun 01, 2024 - 01:47 AM
The RPM drop in your 2000 Mercury 200HP outboard could be due to a few reasons. It's often related to fuel or ignition system issues that become more pronounced at higher temperatures. Here are some potential causes and solutions:
- Fuel Starvation: At higher RPMs, the engine requires more fuel. If there's a restriction in the fuel system, it might not deliver enough fuel, causing the RPM to drop.Make sure the fuel filter is clean and the fuel lines are not kinked or obstructed.
- Ignition System: A failing ignition system can cause performance issues when the engine is under load or at high temperatures. Components like the stator might be failing, and you would need an ohm meter with a DVA adapter to test it.
- Spark Plugs: Worn or fouled spark plugs can lead to misfires, especially at higher RPMs where the demand on the ignition system is greater.Replacing old spark plugs could resolve this issue.
- Additives: Using fuel additives like Marine Sta-Bil can help if the problem is related to fuel quality.These additives stabilize the fuel and can prevent issues related to bad gasoline.
- Check Valve: If there's a check valve in the fuel tank vent system, it could be malfunctioning and causing a vacuum in the tank, which restricts fuel flow. Removing or replacing the check valve might help.
- Fuel Pressure: Ensure that the fuel pressure is within the specifications for your engine. A fuel pressure gauge can help you determine if the pressure is too low when the engine is hot.
Unfortunately, it's incredibly hard to troubleshoot issues online without being able to run tests of any sort. Luckily, you should be able to find the information you are after and the corresponding troubleshooting/replacement procedure in this 1992-2000 Mercury Mariner 200HP EFI Outboard OEM Service & Repair Manual.
