Mercury Optimax 150 troubles

[eod-weissman]

I have a set of Optimax 150's on a Military Zodiac V-Lift RHIB and one is having troubles. The exact nomenclature from the engine is A 2001 Mercury Optimax 150. Model 150CXL OP serial OT393416. As soon as you start the engine it will run, sputter and die. If you put it in Neutral at a higher RPM (around 1000 +) it will keep running but will be rough and somewhat jerks. Anything lower and it runs exceptionally rough and will eventually die. The higher the RPM the better it runs. When running the boat, the good engine at full power/throttle (a bit above 5200 RPM) the other engine in the same time full power/throttle (only 2200 to 2500 RPM) is jerky and lacks any power it had. I have checked the plugs and they seem fine with the exception of #3 & #4 which seems to have more oil on them then the others. I have also changed out all the fuel/water seperator filters. The boat hadn't been run for about 2 months but before that time it ran fine. The nearest Merc dealer here in Japan is about 4 hours away and there is a slight language barrier between us. So if ANYONE can lend me a hand it would be greatly appreciated. Thanks

 

[tuber]

Re: Mercury Optimax 150 troubles

Always happy to help the military, was active for ten, been a reservist for 12. The #3 and #4 plugs are a clue, they're oily from lack of spark. Do the motors have seperate batteries? Check the battery for the 'bad' motor, charge it to the max then run the boat, charging circuit for same,alternator should have more than 14 VDC with motor running less than 13 VDC would be an alternator problem, can read the voltage for this just going across the battery.This could easily be a problem with 2 problems. Then try plug wires, wires go bad easy, laying against the block with bad insulation=no spark. If you can run the motor at night with the cowl off you'll see very fast if the plug wires are shot, looks like the 4th of July.If any wires are against a metal surface use a non-conductive device to move them away with the motor running. Distributor/mag cap, and rotor, check coil(s).

 

[orca]

Re: Mercury Optimax 150 troubles

G'day. the Optimax should have a self diognostic system that will help sort out any problems. If you have a multi function guage are any of the lights on. If you have smartcraft guages then they should highlight any problems. Does the motor have platinum plugs if not then fit some. Check all wiring connections, Pull all connections apart, visually inspect, clean and re fit. Pull your plug leads away from the cylinder block(Difficult on these motors, not a lot of room to move). Have the motors been removed and refitted, if so were the oil hoses fitted correctly. Let us know how you get on. Good luck.