no intake

[lam412]

I have a 1997 merc 60hp tracker with 90# compression in all 3 cylinders but no intake in no.3 cyl Why? Any help appreciated.

 

[Faztbullet]

If the cylinder is not pulling fuel you have either a carb or reed problem.....

 

[lam412]

Thanks. I checked both are good.

 

[lam412]

What else could this be if these two things are OK?

 

[Silvertip]

How did you check the carb??. Did you try spraying a fuel/oil mix into that carb?

 

[lam412]

When running and I put my hand over all carbs it chocked, but # 3 no intake.

 

[racerone]

What happened when you had the motor running last ?----Was this a sudden failure at full throttle ?----Have you looked for a hole in the block ?

 

[lam412]

actually yes but i backed off and it ran at half throttle then quit. I got it running at home but it popped and backfired. I went through the carbs, checked the reeds they are like new even switched them around. then realized there was no intake on #3. all three cylinders have 90# compression. Im stumped!

 

[Chinewalker]

Maybe bottom seal blew out. Crankcase pressure and vacuum are needed to draw fuel. If the bottom crankshaft seal tears or rots out, it won't draw fuel.

 

[lam412]

well first of all how do you check? and wouldn't all cylinders be dead?

 

[racerone]

No , because each cylinder has it own crankcase and is seperated from the others !

 

[lam412]

OK. I have the engine at the point I'm looking at the crank shaft. Would I be able to see the seals?

 

[Chinewalker]

The lower main seal would be in the bottom end cap. Not visible from the reed plate area... Make sure you exhaust all other options before digging in, as you'd need to pull the powerhead to get to it.

 

[lam412]

first of all, thank you. second, what other options do i have?

 

[Chinewalker]

With the carbs off and the reed plates in place, spin the motor over and see if the reeds in the bottom cylinder actually move. They will vibrate with each piston stroke. If they don't move at all, or if you can't hear air moving in there, it's likely the seal is shot.

 

[lam412]

Thank you. I appreciate the help. I'll try it.

 

[lam412]

Can you tell be where to find this seal?

 

[Chinewalker]

If you meant where can you find it in the motor, it is in the lower bearing cap at the base of the crankshaft.

If you meant, where can you find one to purchase, likely get it at a Mercury dealer, or any of the various online sources that deal in OEM parts.

 

[lam412]

i'm pulling the powerhead and i have disconnected all lines,fuel,elec.,linkage,etc. i also pulled the six large mounting bolts. Do i have to disconnect anything else?

 

[Silvertip]

Did you pull #3 plug to see if there is a hole in the piston?