Engine power loss

[Mwilson18]

After a long road of troubleshooting, im still having trouble with my 1989 mercury 2 stroke 60hp outboard. My top speed is 7mph (on a 15ft fiberglass bass boat), and I just sent it in to the shop where they told me I had a spun prop, bent prop shaft, corroded carrier bearing etc., and they repaired all those lower unit issues that they found.
After a trial in the water today, there was almost no difference in speed/power. Another frustrating thing is that my boat is not equipped with a tachometer.
My ignition system is completely checked out ( i believe), I have a 3/8 spark air gap from all spark plug wires. I have changed out the power pack and spark plug wires as well just to be sure and still no difference.
The only notable thing is that I have 120psi in the top cylinder, and 140psi on the bottom two. Could this indicate something wrong with my top cylinder?

 

[Chris1956]

Your compression is fine. I think your shop is part of the problem. Bent propshafts cause noticeable vibration in the drivetrain, and corroded bearing carriers don't cause any issues at all. They probably just needed to make that balloon payment.

if your engine revs up and has a load on it, but speed doesn't increase, either your prop has a bad hub. if the engine revs up with seeming to have a load on it, the driveshaft has an issue or the gearcase has an issue.

if the engine doesn't rev up, you have some other engine issue. Dirty carb, bad ign system, timing issue...not sure.

JMO

 

[Mwilson18]

Your compression is fine. I think your shop is part of the problem. Bent propshafts cause noticeable vibration in the drivetrain, and corroded bearing carriers don't cause any issues at all. They probably just needed to make that balloon payment.

if your engine revs up and has a load on it, but speed doesn't increase, either your prop has a bad hub. if the engine revs up with seeming to have a load on it, the driveshaft has an issue or the gearcase has an issue.

if the engine doesn't rev up, you have some other engine issue. Dirty carb, bad ign system, timing issue...not sure.

JMO

I believe I found the issue today! I found that when I throttle up, it only opens up one of my 2 carburetor’s butterfly’s. When taking the carburetor’s out I found that the throttle lever linkage was snapped off and the bottom carb wasn’t opening at all. I’ve machined a makeshift linkage for it and they both open simultaneously now. I would assume this is the issue? Going to test on the pond tommorow.

 

[Chris1956]

So your shop didn't see that? Get a new shop.

 

[Mwilson18]

I was thinking the same thing, not sure how that got overlooked. Thanks for your help Chris

 

[RMClark]

Regarding the tachometer: You can outfit a tach on your motor for less than $15. Do a search for digital tachometer and take your pick. They install quickly and most also have a runtime hour meter. I put one on my Merc outboard primarily to time maintenance intervals, but the tach was useful for the break-in period.

 

[Mwilson18]

Regarding the tachometer: You can outfit a tach on your motor for less than $15. Do a search for digital tachometer and take your pick. They install quickly and most also have a runtime hour meter. I put one on my Merc outboard primarily to time maintenance intervals, but the tach was useful for the break-in period.

That’s a great suggestion. I’ll have to look into that, thanks!