1978 140 hp mercury power problems

[aps71285]

Idk chris i dont think it was a lean condition or overheating. I think i just pushed it too hard

 

[cuenta619]

Idk chris i dont think it was a lean condition or overheating. I think i just pushed it too hard

5k rpm is In the range how many turn out had the carbs mix screw

 

[Chris1956]

Just so you know, the carb mix screw only affects the motor up to 1200 RPM or so. At that point the main jet (bottom of carb, under the brass plug) controls the mixture. If that jet is clean, the high speed mix should be fine.

 

[cuenta619]

Just so you know, the carb mix screw only affects the motor up to 1200 RPM or so. At that point the main jet (bottom of carb, under the brass plug) controls the mixture. If that jet is clean, the high speed mix should be fine.

Good info.
Thank sr. Everyday I learned more read your post
Exelent.

 

[Faztbullet]

. Cyl 1 is down to 90 psi and 3 is at 30.

Trigger went bad....Distributer trigger can do some goofy and unexplainable things when going bad. Learned this years ago at Mercury school

 

[aps71285]

Idk how to get a pic uploaded of the spark plug but something definitely came apart inside. Ill keep tyring to up load oic

 

[Chris1956]

Check around the entire crankcase. If a bearing or rod failed, you will see the exit wound.....

 

[cuenta619]

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Idk how to get a pic uploaded of the spark plug but something definitely came apart inside. Ill keep tyring to up load oic

what kind of spark you were using
US like this in the pic.

 

[aps71285]

Yes how did you upload that pic

 

[aps71285]

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This is what the #1 and #3 spark plugs look like. The stuff on the wnd appears to be aluminium but its stuck on there it doesnt wipe off

 

[aps71285]

Chris1956 will parts off of my 140 interchange with an 1150?

 

[Faztbullet]

This is what the #1 and #3 spark plugs look like. The stuff on the wnd appears to be aluminium but its stuck on there it doesnt wipe off

That aluminum throw off from piston dome erosion due to preignition, take a knife and it will pop off plug as a cast disk. Depending on 115 year model a lot of parts will interchange...

 

[aps71285]

Timing issue Fazt?

 

[cuenta619]

you're talking about
the maximum spark advance ??
I can't go out and test the motor by bad weather here in fl.
explains a little more to not make the same error.

 

[Faztbullet]

No since testing it as its a goner......

 

[aps71285]

Pulling it apart today to see what broke. I will post pics asap

 

[aps71285]

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[aps71285]

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[aps71285]

That is piston 3. It is scored on the side pretty bad, and looks like the top was melting. What caused this? Also that piston is only a 2 ring piston and the rest have 3. Is that normal. Its also the only one stamped .015 on the top.

 

[Faztbullet]

Like I said bad trigger, eroded dome from preigniton