Originally Posted by MrTsuth
I have a 1996 Maristar 225v... It ha run flawlessly all summer long. It missed about 2 weeks between use due to weather... Suddenly, the engine will not throttle higher than 2000 RPMs... I can't tell if it is flooding or starving... Or if there is some sort of safety that is limiting it.... Any suggestions on what it may be and where to begin my troubleshoot?
2000 RPM is the magic number for overheat-induced RPM reduction, especially if it runs lumpy when this happens. Make sure the impeller is good, the raw water pump cover is tight and well-sealed and no rubber parts from an old impeller are clogging the thermostat(s) or passages. If that is good, look at the wires going to the ECT (Engine Coolant Temperature) sensor. If the wires going to it have melted due to a bad engine overheat, it will tell the ECM that it's overheating, even if it's not. If the wires are good and the plug is fully engaged, measure the sensor's resistance- I have posted a chart here so many times without a mod making it a sticky that there's no reason I should have to do it again.