How JustAnswer Works:
  • Ask an Expert
    Experts are full of valuable knowledge and are ready to help with any question. Credentials confirmed by a Fortune 500 verification firm.
  • Get a Professional Answer
    Via email, text message, or notification as you wait on our site. Ask follow up questions if you need to.
  • 100% Satisfaction Guarantee
    Rate the answer you receive.
Ask Noel Schembri Your Own Question
Noel Schembri
Noel Schembri, Marine Technician
Category: Boat
Satisfied Customers: 1954
Experience:  Advanced technical diploma
Type Your Boat Question Here...
Noel Schembri is online now
A new question is answered every 9 seconds

Engine is a 2004 Yamaha 150 TXRC, 2-cycle (425 hrs). Problem

Customer Question

Hello. Engine is a 2004 Yamaha 150 TXRC, 2-cycle (425 hrs). Problem started with dashboard digital readouts: First noticed boat speed over water was way higher than GPS-derived speed. Then tach failed (0 rpm). Engine running strong. About 10 minutes after tach failed engine abruptly went to about 1/2. speed (hard to be precise as tach failed). Engine sounds great, no misses or smoke; just 5 knots when I was going 10. Throttle did not seem to affect rpm and left throttle set for 10 knots. Headed home with engine sounding great but tach reading 0. Engine would surge periodically. Tach would begin working and went to cruising at 25 knots (3400 rpm). During this time, throttle would work. Then engine would abruptly slow to 5 knots. Sometimes surge for seconds, sometimes run well for minutes. Tach readout varying all over through actual rpm pretty constant until surging back to throttle setting. Noticed today that batteries seem to be slowly dropping in voltage (12.8 to 12.4 overnight) although nothing is turned on (main battery switch is left on). Engine is not missing. Plugs are good as is fuel and filters (no water in fuel). Pretty sure problem is electronic as first indication were errors in the electronic dashboard readouts and engine runs smooth and quiet although dies when set at idle. Sure appreciate any help - Al
Submitted: 2 years ago.
Category: Boat
Expert:  Noel Schembri replied 2 years ago.

Hello my name is ***** ***** I will assist you. I have to agree with you that the problem is electronic related. I suggest you first start by checking all the wiring connections both at the dash (gauges / ignition switch etc) and at he other end on the engine. Remove and apply some contact cleaner to it and replace and see how it goes. Keep me updated.