I have a 2009 evenrude H.O. 150 that I am truble with. the problem I am having is that at high RPM's the engine will momentarily drop very low in rpm but then quickly shoot back up to the normal rpm that I am running at. This is a new boat to me so I dont know how the old owner treated it but I have not read lined it. the problem starts happening arround 4000 RPMs but dose not happn at all or less frequently at lower rpms - 3000 rpms or so. I have changed out the sparkplugs with the correct champion plugs for my year and model, gapped and indexted them correctly and that did not help my problem, I am now thinking that it is fule related thinking maybe the high pressure pump is going out, I have the equipment to test fule pressure comeing off this pump as well as EvDiag to see if my engine is thorwing any codes but have not yet been able to test these two things because I havent had a weeked free from college recently. My question is has anyone had a similar problem or have any ideas other than the high pressure fule pump that I could potentally trubleshoot and get my boat working again? Thanks!
It has to be determined if it is a fuel or electrical (ignition) related problem first.
Monitor the electric pump fuel pressure and the engine running parameters when the motor acts up to look for any abnormalities. The factory service manual is recommended for procedures and specifications. You can order one from your dealer.
"There is never just one thing wrong with a boat";
-- Travis McGee, main character in a book series by John D. McDonald
The factory recommends that a properly trained technician service your Johnson or Evinrude outboard motor. Should you elect to perform repairs yourself, use caution, common sense, and observe safety procedures in the vicinity of flammable liquids, around moving parts, near high-temperature components, and working with electrical or ignition systems.
The information offered here is only general in nature and should not be construed as complete factory approved procedures, techniques, or specifications. Always use the proper service manual for your motor, up-to-date service literature, the correct tools, and have an understanding of how to proceed with troubleshooting and repair methods. If you are unsure or uncomfortable with a procedure, a situation, or a technique, enlist the services of a factory trained technician.