2012 150hp Mercury Optimax sputtering and almost quitting.

[Hefner413]

2012 150hp Mercury Optimax 2 stroke. Serial number 1B934227

You all have been invaluable and I'm needing help once again. I bought this at the beginning of the season with only 40 hrs on it (I assume it sat for a couple seasons without use). I was having issues keeping it running shortly after I bought it... and replaced the low pressure fuel pump, the throttle position sensor, fuel line and primer bulb, spark plugs (non OEM though), the oil filter and the water pump. I also checked thermostats (functioned fine) and bought a mercury vessel view. I run only ethanol free. The engine ran fine this season until the past few weeks... It has begun to sputter when the engine is first started / cold. It seems to run fine once I get it running / warmed up / above 3K rpms a bit. Then it will run fine for the day. But I have noticed that the sputtering is getting worse and worse each time I start it up for the first time for the day. I've now taken it out for the season and want to fix the issue. Any ideas of where to start? My fist thought was cleaning the carburetor. Thoughts?

[SilverFox579]

Are you pumping the bulb prior to every engine start? If not, try it and report back. NGK IZFR5G is the ONLY correct plug for this engine.

Btw, there is no carb on an Optimax, it is direct injected.

[Ranger519VS]

Not a bad idea to have the injectors serviced also visually check the reeds for cracks or chips out of the tips.

[Hefner413]

Are you pumping the bulb prior to every engine start? If not, try it and report back. NGK IZFR5G is the ONLY correct plug for this engine.

Btw, there is no carb on an Optimax, it is direct injected.

Thanks Phil. I was wondering if it was a bulb priming issue also. But it seems to do this both if it’s primed or not. And I’m going to get the correct plugs… I shouldn’t have rushed and got what was at the store. I’ll order the correct ones.
And yeah, since my post, I looked and said… hmm. No carb. ��

[Hefner413]

Not a bad idea to have the injectors serviced also visually check the reeds for cracks or chips out of the tips.

Thanks Butch. I saw another thread that mentioned the reeds. I’ll take a look. Thanks!

[Hefner413]

Not a bad idea to have the injectors serviced also visually check the reeds for cracks or chips out of the tips.

Hey Butch, I consider myself somewhat handy... But is injector servicing and reed replacement difficult or do I need specialty parts or a DDT at any point?

[SilverFox579]

If you need your injectors serviced I highly recommend you contact European Marine. Reeds aren't difficult if you are mechanically inclined. I did a pictorial when I removed my rails and injectors for service and replaced reeds you can find in the FAQ at top of forum.

Fuel Rail and Direct Injector Removal

[EuropeanAM]

+1

One thing you didn't mention: How many hours are on your engine NOW?

May be as simple as needing maintenance.

[Hefner413]

+1

One thing you didn't mention: How many hours are on your engine NOW?

May be as simple as needing maintenance.

I am at 83.7 hrs now. Thanks

[EuropeanAM]

I would pull the spark plugs and inspect them (planning to replace them with correct, properly-gapped and torqued spark plugs).

[Hefner413]

I would pull the spark plugs and inspect them (planning to replace them with correct, properly-gapped and torqued spark plugs).

Thanks! My NGK IZFR5G plugs are on their way. I've read that 20ftlb is the correct torque? But I can't seem to find the correct gap. Will I need to adjust gap for the optimax?

[SilverFox579]

There's a great FAQ at the top of the forum with topics covering almost everything you can think of. Assuming your 150 is NOT a ProXS torque is 20lb ft, gap is .032" - .033", plug gaps MUST be checked and verified even if you buy "pre-gapped" plugs (I never do).

Oil, Battery, Spark Plugs, Fuel and Fuel Additive Recommendations

[Hefner413]

Well, seems like those spark plugs were the issue. Pulled out these and replaced with the correct plugs at .032. No sputtering now. 2F9BD619-959C-486A-A97D-1769A9BF9C3F.jpeg7F6B3F67-73BA-46A2-88A3-C990010FA2F9.jpegE4E14C9E-689E-4341-B0A8-F7A87FA4B13A.jpeg

[EuropeanAM]

Oh gosh. Not sure what those plugs are, but I would definitely stick with the factory recommended plugs (only) for this engine.

[SilverFox579]

WOW!

[Hefner413]

Oh gosh. Not sure what those plugs are, but I would definitely stick with the factory recommended plugs (only) for this engine.

Yeah, I took the oem spark plug to autozone and they said this was the compatible replacement… one of the E3 spark plugs I guess. These had less than 40 hrs on them. Lesson learned. Only NGK IZFR5G going forward. Thanks again all!

[EuropeanAM]

You're lucky. More often than you would expect, "equivalent" spark plugs make for some real carnage.