150 Hp 2 stroke Optimax will not run at low idle.

[lmbr]

Just recently got this one. Will start and run at fast idle but when I reduce it, it dies. Had a mechanic tell me that a Optimax will do that but it has a part to allow it to keep running. Any help sure would be appreciated. It is a 2011 model 150 Optimax.

 

[Faztbullet]

Compression and spark test needed

 

[racerone]

Agreed.-----But test air pressure and inspect that BIG $$$ air compressor too.

 

[lmbr]

The man I purchased this motor is a Mercury mechanic at a boat dealer and he told me he had completely reworked this engine and everything was good. He said the problem I am having is caused by a switch located close to where the throttle linkage attaches to the motor. I previously sprayed the area with WD40 and worked the throttle back and forth and everything worked then. Now, a couple of weeks later, it is back to doing the same thing. Otherwise, the engine runs great.

 

[racerone]

Take it back to the mechanic.-----Should be able to fix this in minutes.

 

[lmbr]

I got the part Installed it—still the same problem. The fuel filter canister looks like it hasn't been changed in a while. Should I check the fuel system? It will try to start when the throttle is not advanced but not start. Will start when I open it enough so it starts at 4000 rpms. I can then slowly reduce it until I get to 1000 - 1200 rpms and then it dies. The first time I took it to the lake it did this but after many restarts, I was finally able to get out on the lake. On return to the ramp, it was still a little hard to keep running.

 

[alldodge]

The man I purchased this motor is a Mercury mechanic at a boat dealer and he told me he had completely reworked this engine and everything was good.

Don't know the motor but sure sounds like the mechanic was lying

 

[QBhoy]

have you ruled out the fuel quality and fuel delivery means ? tank pick up, fuel connector fitting etc etc ?
Also the fuel fine strainer in the fuel rail ? Sometimes called the HP fuel strainer screen or similar ? It is like a wee insert that sits in the fuel rail that supplies the injectors. Not too familiar with the Optimax, but almost sure they likely have one of these, like the rest of the modern injected 4 strokes that size certainly do.

 

[lmbr]

have you ruled out the fuel quality and fuel delivery means ? tank pick up, fuel connector fitting etc etc ?
Also the fuel fine strainer in the fuel rail ? Sometimes called the HP fuel strainer screen or similar ? It is like a wee insert that sits in the fuel rail that supplies the injectors. Not too familiar with the Optimax, but almost sure they likely have one of these, like the rest of the modern injected 4 strokes that size certainly do.

As soon as it warms up some I plan on starting to go through the fuel system to make sure everything is clean and OK

 

[racerone]

Do a compression test.---Post the numbers here.

 

[lmbr]

Do a compression test.---Post the numbers here.

Finally quit raining. Did compression test. Results: Starboard side top 71#, middle 72#, bottom 71#. Port side top 81#, middle 76#, bottom 85#. Neediness to say I was shocked since the mechanic I bought it from told me he had gone thru the engine and fixed everything that was needed.

 

[racerone]

Does not sound promising.---But try another gauge first.

 

[QBhoy]

Agree. Try another good gauge. Be a hell of a thing if those figures were right and accurate.
Was that a warm test

 

[jimmbo]

Deleted

 

[lmbr]

Was not a warm test since starting is a problem. Heard from the mechanic and he assured me that he went thru the engine and that it had 95 - 100 psi on all cylinders. Both oil tanks are full and sealed. There is not a low oil alarm. If the oil injector pump was not working, would there be an alarm? I'm wondering if there is no oil being mixed with the fuel and damaging the cylinders. Is there a way to check that. (I have ordered a repair manual but it won't be here until next week.)