Suggestions Needed for Mercury 150 EFI

[Tennessee T]

I am the original owner of a 1997 Mercury 150 EFI, serial number 0G478627. Amazingly, after 23 years of club tournament fishing, this engine still runs and performs great. However, over the last couple of years, it is getting to where it can be more difficult, at times, to start than others. Sometimes it fires right up on the first try, other times and worst case scenario, it takes 3 tries, none of which requires lengthy cranking.

The only thing outside of routine maintenance, i.e. replacing water pump impellers, lower unit gear oil, spark plugs, fuel filters, and greasing the pivot points, that I have done to this engine is rebuild the pulse pump in the fuel system in 2007. Knock on wood, I have not had to make any repairs to it. It is also worth stating that I am very content with this engine and the boat that it powers, so I have every intention of keeping this engine, and boat, for many more years. Also, I am mechanically inclined and feel very comfortable around my engine. I do have a Mercury service manual for this engine to help me along.

I have three questions:

1. Considering the age of this engine, what would you recommend doing to it to fine tune it to be the best it can be and to prolong it's longevity? To be clear, I'm not looking for higher performance upgrades here, just keeping it stock. I want to consider anything and everything.
2. What could be the possible causes of the sometimes difficult starting that I described above?
3. I would like for someone to confirm for me that I have the correct service manual. The part number of the manual that I have is 90-824052R3. The only reason I ask this question is, for example, in the section titled "Timing, Synchronization, & Adjusting", the only EFI models that it references are the 150, 175, & 200 XRI's and the 150 and 200/225 Pro Max/Super Magnum. I am a little confused as to why I don't see 150 EFI listed.

Thanks in advance and I look forward to hearing the responses.

[JOE54]

fiber reeds for safety mabe injector service q kleen and qcare always,may need good tune up with all sensors tested and verifiedtpi adjusted and linkages set up I like BR8HS-10 plugs also, manual is correct xri is same engine as efi fancy name, GOOD LUCK TOMMY

[Tennessee T]

fiber reeds for safety mabe injector service q kleen and qcare always,may need good tune up with all sensors tested and verifiedtpi adjusted and linkages set up I like BR8HS-10 plugs also, manual is correct xri is same engine as efi fancy name, GOOD LUCK TOMMY

Thanks Joe54!

[JOE54]

yea man

[Grandpa]

I have the same engine 150efi that has been sitting idle for 10 years, i am just now starting the process to safely get it back in service.

[leonreno]

Is this the motor where the idle stabilizer can be removed if it
starts causing problems? Maybe that could be his problem?

[JOE54]

sure could be

[Tennessee T]

Interesting...I'm going to have to educate myself about the idle stabilizer. Is it an electronic component or mechanical? And would it be better to repair/replace it as opposed to removing it all together?

[leonreno]

Search on here for info, bunches here. It’s an electronic box that is supposed to help idle and shifting. Many people remove it and then set the timing manually.

[Tennessee T]

Thanks leonreno. I have already been searching and found lots of information about the idle stabilizer. To be honest, I'm not real comfortable removing a component that Mercury felt was necessary for the operation of this engine. I have found a test procedure for the idle stabilizer in my service manual and will go through that first. If it tests bad, my plan A would be to replace it, assuming it is still available and it doesn't cost an arm and a leg, plan B would then be to remove it.

[Tennessee T]

fiber reeds for safety mabe injector service q kleen and qcare always,may need good tune up with all sensors tested and verifiedtpi adjusted and linkages set up I like BR8HS-10 plugs also, manual is correct xri is same engine as efi fancy name, GOOD LUCK TOMMY

Joe54...what gap do you recommend on those BR8HS-10 plugs?

[EuropeanAM]

Thanks leonreno. I have already been searching and found lots of information about the idle stabilizer. To be honest, I'm not real comfortable removing a component that Mercury felt was necessary for the operation of this engine. I have found a test procedure for the idle stabilizer in my service manual and will go through that first. If it tests bad, my plan A would be to replace it, assuming it is still available and it doesn't cost an arm and a leg, plan B would then be to remove it.

You can get rid of that stabilizer with ZERO problems. Mercury installed it because they did not know what type of boat the engine would land on, let alone what prop pitch it would have. It is very conceivable that some engines were as low as 10-11 pitch, others nearing 30 pitch. But ALL of them needed to be able to idle out of the box.

Hence an Idle Stabilizer Module was used (it could manipulate timing to stabilize idle speed).

If you stick with roughly the same prop pitch- it is not needed (the engine can have a complete Sync-n-Link Procedure completed, and then run just as well, or perhaps even better).

[JOE54]

Joe54...what gap do you recommend on those BR8HS-10 plugs?

.035

[Tennessee T]

You can get rid of that stabilizer with ZERO problems. Mercury installed it because they did not know what type of boat the engine would land on, let alone what prop pitch it would have. It is very conceivable that some engines were as low as 10-11 pitch, others nearing 30 pitch. But ALL of them needed to be able to idle out of the box.

Hence an Idle Stabilizer Module was used (it could manipulate timing to stabilize idle speed).

If you stick with roughly the same prop pitch- it is not needed (the engine can have a complete Sync-n-Link Procedure completed, and then run just as well, or perhaps even better).

Thanks EuropeanAM. After reading your explanation, I am now seriously considering removing that stablizer. I had already planned on doing a full Sync-and-Link Procedure, along with injector service, VST and fuel system cleaning, and replacing OEM reed valves with carbon fiber ones, and a few other things to make my engine as good as it can be. I will be calling your shop soon to discuss your services.

.035

Thanks again Joe54!

[Tennessee T]

You can get rid of that stabilizer with ZERO problems. Mercury installed it because they did not know what type of boat the engine would land on, let alone what prop pitch it would have. It is very conceivable that some engines were as low as 10-11 pitch, others nearing 30 pitch. But ALL of them needed to be able to idle out of the box.

Hence an Idle Stabilizer Module was used (it could manipulate timing to stabilize idle speed).

If you stick with roughly the same prop pitch- it is not needed (the engine can have a complete Sync-n-Link Procedure completed, and then run just as well, or perhaps even better).

Don,

I am beginning the process of removing my idle stabilizer and am wondering if I also need to remove the Idle Stabilizer Shift Kit, or do I leave that in place?

[EuropeanAM]

I would leave that in place for now (it does have some benefit in that it can make it easier to shift out of gear).

[Tennessee T]

I would leave that in place for now (it does have some benefit in that it can make it easier to shift out of gear).

Okay. Thanks again Don!!