275 mercury 2 stroke

[Thompson4932]

I was out in the boat running at 5000rpm just put a new prop on. Boat was on plane doing very well. Then it just dropped off to 3000 rpms by its self. Wouldn't go any higher no matter what I did. When take out of gear motor will reach the higher rpm. But it will not under a load. I know it could be a lot of things. I checked the compression its all the cylinders are with in 1 lb of each other. I would like to do the work myself to get to know this motor better. All help would be helpful.

 

[racerone]

Year / model / serial # should be posted.

 

[dingbat]

Wasn’t aware Mercury made a 275 HP 2 stroke?
Sure it’s not a 4 stroke Verado?

 

[Thompson4932]

1993 offshore OD214385

 

[Thompson4932]

Year / model / serial # should be posted.

1993/ offshore/ OD214385

 

[dingbat]

1993/ offshore/ OD214385

Interesting... didn’t know Merc made a 275 that early

 

[Faztbullet]

Check spark as sound like it dropped a bank of cylinders...will rev fine with no load also

 

[Dukedog]

not much experience with tha 3.4... but it sounds like a stator issue.. if it idles fine and goes to tha 2800/3000 rpm under load threshold as normal is what makes it sound like high side of stator.. plus what Faz says.. have you looked for an oem manual? it wiould help ya a lot......

 

[Dukedog]

Interesting... didn’t know Merc made a 275 that early

they built a 3.4 motor from '83 ta '94 with 300 and 275 ratings.....

 

[Thompson4932]

Here are pics of the motor

not much experience with tha 3.4... but it sounds like a stator issue.. if it idles fine and goes to tha 2800/3000 rpm under load threshold as normal is what makes it sound like high side of stator.. plus what Faz says.. have you looked for an oem manual? it wiould help ya a lot......

Have a repair manual and the oem book. But it doesn't say much on trouble shooting. More on how to replace.

 

[Dukedog]

(under a load) does it act normal at idle up to tha 2800/3000 rpm range???

 

[Thompson4932]

(under a load) does it act normal at idle up to tha 2800/3000 rpm range???

Yes

 

[Thompson4932]

Yes

But seems to a little rough

 

[Dukedog]

my "internet money" would guess stator but its still justa guess from tha keyboard!..... does your manual give test values of any of tha 'lectrics???

 

[dingbat]

But seems to a little rough

I suspect the stator diagnosis is correct

Had the same issue on a 200 hp Black Max. 35 miles out when it let loose. Long slow ride @ 2000 rpm

Have you done a compression check?

 

[Thompson4932]

I suspect the stator diagnosis is correct

Had the same issue on a 200 hp Black Max. 35 miles out when it let loose. Long slow ride @ 2000 rpm

Have you done a compression check?

Yes all cylinders 120,121

 

[Thompson4932]

my "internet money" would guess stator but its still justa guess from tha keyboard!..... does your manual give test values of any of tha 'lectrics???

No it doesn't even go into test the stator

 

[Dukedog]

you might look on CDI website for stator values and replacement???

tha 3.4 is an odd bird motor anyway.. not much info out there about it.. values not in tha OEM manual is strange for Merc!.. i've looked at everything i have access to and came up with "0" other than parts list... good luck with it!

 

[Thompson4932]

Thanks I have the mercury oem repair manual. It gives the part break down an part numbers. I just received the flywheel puller that they recommended. So hopeful I get this figured out. But should I change the trigger mechanism also if it ends up being the stator?

 

[Dukedog]

maybe if its not to expensive.. tha trigger is tha most dependable electric part on tha motor as for as i'm concerned!.. since i've been doin' these V6 things (since '76 but not tha 3.4).. i've never had a trigger fail!