Help: 2010 200hp Pro XS

[btribby]

I am in need of help of trying to diagnose some issues on my motor that popped up over the weekend. To start, I live a LONG way from any Mercury mechanic, which is why I am trying to diagnose the issue(s) and fix myself.

I have a 2010 200hp Opti Pro XS on a BassCat Pantera 2.

The first issue I noticed was at full throttle I could feel the boat surging a bit. I began to watch the rpms and they were bouncing around, approx 100 to 150 rpms. I also could not get full power, about four to five mph slower than normal. I was running long distance, ~45 miles. At times it would work itself out, there would be no lunge and I would be back to full power and speed but then go back to lunging. Oddly enough, If I back off the throttle just a tiny bit the boat would quit lunging and increase speed and rpms.

The second issue are hard starts. Which I've experienced in hot weather before. But, these kept on getting worse throughout the week but were more prevalent later in the day, each and every day. The final day the hard starts began from the beginning. I would keep the key turned and it would wind probably eight to ten times before firing up. Sometimes it took two or three of these eight to ten winds to get the engine turned over. I would engage the gears and proceed to warm the engine up at basically idling speed until the thermostats kicked in. Then hammer down. It was really bogging down, like it wasnt getting fuel then suddenly I could hear/feel it be back to normal and off I went. The last day of the trip, these problems were more and more prevalent until the motor wouldnt start. I primed the bulb and it would start, then immediately die. That was happening over and over. I engaged the "choke" and had the throttle engaged and it started right up. Put it back to neutral and into forward and again it was bogged down, like it might die and then return to a normal feel/sound and off I went.

40 hours ago, I replaced the spark plugs and main fuel filter. My first guess is this is an air/fuel filter issue. But, any ideas and thoughts on where to start would be much appreciated. Thank you.

Serial Number: 1B801620

[castforcash]

Need to post your serial number. Explain exactly how you gapped your spark plugs and what plugs did you use? Some of your post is confusing. There is no choke on a optimax motor. Also, you said you started it in gear, that's not possible as the neutral safety switch will not allow the motor to start while in gear. What octane gas are you using? Are you priming the bulb before every start up? Do you use any fuel additives, ie. quicken, quick care in every tank of gas?

[btribby]

Need to post your serial number. Explain exactly how you gapped your spark plugs and what plugs did you use? Some of your post is confusing. There is no choke on a optimax motor. Also, you said you started it in gear, that's not possible as the neutral safety switch will not allow the motor to start while in gear. What octane gas are you using? Are you priming the bulb before every start up? Do you use any fuel additives, ie. quicken, quick care in every tank of gas?

Thanks for the serial number reminder.

- I ordered the spark plugs directly from mercury. I believe they are NGX (I ordered and installed them 13 months ago so I dont recall exactly). I gapped them with a gapping tool I purchased at an auto parts store. I gapped them to what is posted in this Mercury Forum. Im not going to go look it up now, but if I recall its .032-.033. I understand how important installing the proper gapped plug is. Im 100% confident I did everything right with the plugs.

- I know there isnt a "choke". Im brain dead today and didnt really know what its called. I overpassed putting it into gear to be able to rev it in neutral by pushing in the button at the bottom of the shifting lever.

- I always use 87 octane gas and every tank gets quickleen and quickare. The last tank of the season gets ethanol free 91 octane, quickleen/kare and quickstore.

- I have never had to manually primed the bulb before yesterday.

[SilverFox579]

You will read over and over here, and for good reason, pump the bulb prior to every engine start. Short version of why is today's "fuel" tends to vaporize in the lines and the pulse fuel pump, which supplies liquid fuel to your VST, cannot process vapors. Being it is a diaphragm pump it must have liquid fuel to function.

Spark service interval is 100hrs OR annually whichever comes first. Yes, a plug can cause what you're experiencing. Must ALWAYS use a wire gauge to set plug gap, never ever use feeler gauges. Your engine should have NGK IZFR5G plugs gapped .032" - .033". Oil, Battery, Spark Plugs, Fuel and Fuel Additive Recommendations

Should not rev your Optimax in neutral, doing so will set neutral overspeed faults in the PCM.

While there may be other factors causing your run issue, I would install a new set of properly gapped plugs first and make it a habit to pump bulb prior to every engine start and see if that helps.

[btribby]

You will read over and over here, and for good reason, pump the bulb prior to every engine start. Short version of why is today's "fuel" tends to vaporize in the lines and the pulse fuel pump, which supplies liquid fuel to your VST, cannot process vapors. Being it is a diaphragm pump it must have liquid fuel to function.

Spark service interval is 100hrs OR annually whichever comes first. Yes, a plug can cause what you're experiencing. Must ALWAYS use a wire gauge to set plug gap, never ever use feeler gauges. Your engine should have NGK IZFR5G plugs gapped .032" - .033". Oil, Battery, Spark Plugs, Fuel and Fuel Additive Recommendations

Should not rev your Optimax in neutral, doing so will set neutral overspeed faults in the PCM.

While there may be other factors causing your run issue, I would install a new set of properly gapped plugs first and make it a habit to pump bulb prior to every engine start and see if that helps.

I have never heard of priming the bulb before every start. Interesting. I will replace all fuel lines and the priming bulb. It won’t let me attach any photos. But I have a circular gapping tool and I am using the plugs you mentioned. I gapped them to the appropriate space. I will take the plugs out and inspect them, probably replace them. That would be great if that’s the fix.

[06 SB]

It has been a long time since I worked on that motor but spark plugs never lasted more than a year. It would get finicky with 11-12 month old plugs. You may want to look into the condition of the spark plug wires. I replaced the fuel lines and bulb but would be worth doing again. I would do a compression and leak down check and also test the compressor too.

[castforcash]

I have never heard of priming the bulb before every start. Interesting. I will replace all fuel lines and the priming bulb. It won’t let me attach any photos. But I have a circular gapping tool and I am using the plugs you mentioned. I gapped them to the appropriate space. I will take the plugs out and inspect them, probably replace them. That would be great if that’s the fix.

Is this the type of gap tool you used?

Screenshot_20210724-141753_Chrome.jpg

If it is and you used it to open the gap by prying against the center electrode then you most likely damaged your plugs.

[Bryanmc57]

Is this the type of gap tool you used?

Screenshot_20210724-141753_Chrome.jpg

If it is and you used it to open the gap by prying against the center electrode then you most likely damaged your plugs.

+1

[SilverFox579]

This is what I use, there are other styles with wire gauge,

FB301A.jpg

[castforcash]

I use something similar to this, but I use side cutters to grip the electrode when adjusting the gap.

Screenshot_20210725-100449_Chrome.jpg

[JOE54]

just watch that pad on grnd strap

[EuropeanAM]

Definitely start with the basics, and catch up your needed ANNUAL Maintenance. You would probably not have purchased spark plugs direct from Mercury, since they don't sell to consumers (would have to come from a dealer).

Definitely pump that primer bulb firm before EVERY engine start. ESPECIALLY important when temps reach 60F or higher.

[btribby]

Definitely start with the basics, and catch up your needed ANNUAL Maintenance. You would probably not have purchased spark plugs direct from Mercury, since they don't sell to consumers (would have to come from a dealer).

Definitely pump that primer bulb firm before EVERY engine start. ESPECIALLY important when temps reach 60F or higher.

What needed annual maintenance are you seeing that I have no done?

[06 SB]

Here is a sticky that Don keeps for your question. Just go over the list and anything that has not been done in the last 364 days needs to be addressed.

Recommended Annual Maintenance

[btribby]

Anyone have the part numbers for the 3/8 and 5/16 fuel lines as well as the primer bulb? Thank you.

[EuropeanAM]

Unless you want a 100' roll, you'll want to contact a dealer (Rhonda, in our Parts Department can sell you what you need, just let her know what lengths).

[btribby]

Unless you want a 100' roll, you'll want to contact a dealer (Rhonda, in our Parts Department can sell you what you need, just let her know what lengths).

Thanks Don. Once I figure out how many feet I need I will give Rhonda a call. I appreciate all your help.

[btribby]

Fuel lines have been replaced
Priming Bulb replaced
External fuel pump replaced
Fuel filter replaced
Spark plugs replaced and properly gapped

That did not fix the problem. It starts but I can't get more than 600 rpms and when its in neutral it runs really rough.

Took it to a mechanic and had him run a fuel and air pressure test. Air pressure checked out fine. But fuel pressure was only 5psi.

Took apart the VST and replaced both pumps.
Cleaned out the VST but there was little to nothing to clean.
Put it back together.

Same problem. 600 rpms. Rough in neutral.

Conducted a spark test in my driveway with earmuffs hooked up. All six cylinders had spark.

Any thoughts on where I should go next?

[06 SB]

The hard start would have me checking the compressor.

[EuropeanAM]

Engine would not run AT ALL with 5 psi of fuel pressure. That test was not done properly, it's a pity that you replaced fuel pumps for that. Hopefully they were OEM Mercury/Quicksilver components.

Is the engine running poorly when you try to accelerate, or when NO THROTTLE IS APPLIED? Keep in mind- you should never apply throttle when the engine is in neutral.