2020 Merc Pro XS V8 200

[fuelleak]

Serial # 2B741447. Motor has been missing since spring. The worst part was it had a tendency not to start at most inconvenient times like winning bag and you need to get to weigh in. Turn the key and zero. It was sporadic so first appointment everything was working for mechanic of course. That was finally fixed as mechanic found bad module and replaced. That took 2 months. He didn't address the miss though on first and second visit though. Took a month again to get in for next appointment for miss. Mechanic is now saying that its the spark plugs and that the plugs are not available for 3 weeks. This motor has been a real gem so far. Told my partner I would look for plugs for him. Don, do you have those plugs in stock?

[EuropeanAM]

We normally stock the LKAR7C (8M0135348) spark plugs- see Rhonda's post (pinned at the top of the Forum) for Parts Information, Ordering, Etc.

Don't overlook the plug wires- inspect every inch of them for signs of leakage or damage.

[fuelleak]

Thanks Don! We'll take a look at the wires too.

[fuelleak]

Update: after Mercury mechanic and Mercury themselves beating there heads against the wall with this 200 V8 miss since March it looks like the mechanic has finally found the source of the problem. The trim position sensor was getting wacky readings from 4500 rpm and up. Mechanic had to hook computer up while helper drove boat above that rpm to see on his laptop erratic readings of said sensor which in turn was shutting spark down to a number of cylinders causing the miss.. Kinda of a guardian mode type of thing as sensor was thinking motor was over trimmed and possibly lacking water pressure. This is what I was told by service manager today. They found the sensor at another dealer and it is on its way. What a bizarre deal and what a PITA this new motor has been!

[DaveTTN]

Hope that takes care of it.

[Buck456]

Update: after Mercury mechanic and Mercury themselves beating there heads against the wall with this 200 V8 miss since March it looks like the mechanic has finally found the source of the problem. The trim position sensor was getting wacky readings from 4500 rpm and up. Mechanic had to hook computer up while helper drove boat above that rpm to see on his laptop erratic readings of said sensor which in turn was shutting spark down to a number of cylinders causing the miss.. Kinda of a guardian mode type of thing as sensor was thinking motor was over trimmed and possibly lacking water pressure. This is what I was told by service manager today. They found the sensor at another dealer and it is on its way. What a bizarre deal and what a PITA this new motor has been!

This is not the only v8 merc is beating there heads against the wall over. I hope it works out for u and it's fixed.

[fuelleak]

Buck456, what are the other issues? My personal motor has run extremely well, 2019 250 Pro XS. It did strand me with a voltage regulator failure once and my 20 hr, oil change had a chit load of water in it. I have changed it 4 more times at a total of 113hrs just to make sure that water issues was a fluke, seems it was. Lot of fresh oil for a 113 hrs. It has basically run flawless and pushes my Falcon 205 to 73 loaded with 2 people. So far its behaving like a Toyota.

[Buck456]

Buck456, what are the other issues? My personal motor has run extremely well, 2019 250 Pro XS. It did strand me with a voltage regulator failure once and my 20 hr, oil change had a chit load of water in it. I have changed it 4 more times at a total of 113hrs just to make sure that water issues was a fluke, seems it was. Lot of fresh oil for a 113 hrs. It has basically run flawless and pushes my Falcon 205 to 73 loaded with 2 people. So far its behaving like a Toyota.

Mine is kind of a long story, but in short I've had an intermittent miss since I first got it wet in March. This is the 6th (or 7th) trip back to the dealer. When it's not missing it runs amazing. It can go a few hours and run flawless to running so bad I can barely get on plane. Mercury is supposedly "on it". At this point I have zero faith in Merc or the motor. Mine has been running more like an old Chrysler my mom had when I was a kid.

[DaveTTN]

Mine is kind of a long story, but in short I've had an intermittent miss since I first got it wet in March. This is the 6th (or 7th) trip back to the dealer. When it's not missing it runs amazing. It can go a few hours and run flawless to running so bad I can barely get on plane. Mercury is supposedly "on it". At this point I have zero faith in Merc or the motor. Mine has been running more like an old Chrysler my mom had when I was a kid.

Well that sucks. Mine has ran like a top except for the one shift position sensor/actuator failure that left me and my family stuck on the water at 54 hours on the motor. Hopefully that is the only gremlin and it’s smooth sailing this point forward.

[fuelleak]

Mine is kind of a long story, but in short I've had an intermittent miss since I first got it wet in March. This is the 6th (or 7th) trip back to the dealer. When it's not missing it runs amazing. It can go a few hours and run flawless to running so bad I can barely get on plane. Mercury is supposedly "on it". At this point I have zero faith in Merc or the motor. Mine has been running more like an old Chrysler my mom had when I was a kid.

Buck456, yours sounds like my partners motor except I think my partner got his ironed out. Good Luck brother!

[EuropeanAM]

Guys- While I understand that you're all trying to help "fuelleak"... please keep in mind that there is a STRICT "One engine per post" policy here in the forums. Reading back from the last post (to respond) becomes more than confusing when you have multiple people talking about different engines.

Thank you for your cooperation.

[2dwoods]

I bought the last 2stroke I could find in mid 18 I wish I would have got the 4 stroke but maybe not, of course I know there's a bunch that's probably been flawless