1992 692 Ranger w/ 1992 Mariner 150

[Greenhead]

We were having issues with the prop earlier and couldn't get on plane. We dropped the pitch and some blades and increased the RPMs. It now takes about 100 yds full throttle to get on plane with two guys and batteries, fuel. Top speed is 38 mph. Is this normal with this setup?

[southerncomfort1]

Not even close to how the boat should perform.My guess is your motor is not running properly and lacking real power or you have the wrong prop.What prop and pitch are you running? What is your max rpm you can achieve at WOT? Is motor running smooth from start up to WOT? I would also do a compression check on all cylinders and if that checked out ok then look at your prop, coil packs,ECU or fuel delivery issue as your possable problem.With a 150 you should be upper 40's or better I would think depending on prop used and jump out of the hole strong.

[Greenhead]

One mechanic had said that it is alot of boat for that motor. However I have seen 90's & 115's on much larger boats. It had a five blade SS 21 and now has a 17 3 blade aluminum. All cylinders are around 108 on compression test. Mechanic says all carbs are ok. Not sure what the heck is going on. Does anyone have a similar set up? How does it perform?

[southerncomfort1]

Not the exact same year or motor but I have a 1998 692 with a 175 top speed with 3 blade Raker 20 pitch prop low 50's and screams out of the hole.With a Rev 4 prop 46 on the GPS and again rips out of the hole on plane

[ChuckD]

That is not normal for that boat/motor combo. Been in a 690 with 115hp that performed better.

A 17 pitch on that motor would scream RPMs and hit the rev limiter...

I'd bet you have a motor issue. I have a comparable boat in size with a 175 Merc (1994) and I run a 23P 4 blade. The 150hp motor is the very close (same engine block) to mine.

Changed out spark plugs?

I'd find another (Mercury) mechanic for a second opinion. Something isn't firing on all 6 cylinders properly...could be something electrical, carbs, etc. Lack of power tells me carbs need some fine attention.

I'd also like to see a little higher compression reading, myself.