Hello, this is my first post<br /><br />Can you help me solve a mystery with my 98 honda 90HP 4 stroke engine? here are the description of the symptoms:<br /><br />When I am cruising at 3000 3500 rpm, the engin runs smoothly for a while, but very soon, if I power up to 4000 or more the engin looses power runs only on 3 or 2 cyls and appears to be starved for fuel.<br /><br />This problem happens sporadically but more an more often. When we come back from a fishing trip after having run for 15 min one way; if we suddently power up to max speed; if we run the engine for a long time at 4000 rpm.... <br /><br />Frequency of the pbm has increased. It used to happen every now and then but has become worse. In the past, all we had to do was to iddle, pump the little pump that is between the fuel tank and the engine a few times and the pbm would be solved. This made us believe the pbm was linked to insufficient fuel reaching the engine. But that was not it as pressing on the fuel pump now does not resolve this pbm any more. <br /><br />Strangely enough, when the engine runs on 3 cyls for a long time, and that we have the engine up to 3000 rpm (i have to get home!) it has happened that the engine suddently starts to run correctly again... and then after 10 min of heaven, starts running poorly again...<br /><br />I don't understand it<br /><br />I have tried and changed many things with my mechanic, but the pbm has not yet been solved: <br /><br />1) i have changed both fuel pumps becuase the previous owner had run the engine without openting the fuel vent on the fuel tank. The fuel pumps were shot (apparently). The pbm continues<br /><br />2) I instaled a fuel filter between the fuel tank and the engine to remove the dirt in the fuel tank. Pbm continues<br /><br />3) We changed all spark plugs.. Pbm continues<br /><br />4) we removed, took appart and cleaned the 4 carbs (they were clean), changed the internal fuel filter (it was very dirty : sand, water and even glass pieces) but the pbm continues<br /><br />5) our mechanic contacted the honda company who told us to unplug the electrical contact for the engine trim that is on the engine (not on the controls) due to some interference, the engine ran great for 15 minutes, but then the pbm comes back..<br /><br />6) we hooke the fuel tank directly to the engine, bypassing the fuel filter and making the distance between the engine and the fuel tank much shorter, but the pbm continues. <br /><br />I have heard that a source might be a faulty contact with the oil or water temp.. DO you have any other ideas, have you heard about this before? Have you experienced the same?<br /><br />Thank you very much<br /> <br />Jan
