1999 90hp merc 3 cyl.. no power!!

[dmosher]

Hi,
Im new here and at my wits end with my boat/motor. Heres the deal:
1973 Wellcraft 16'8" fisherman
24" armstrong bracket
1999 90 merc two stroke

All rigging, lines and wiring is brand new
fuel tank cleaned with new pickup and sending unit
new water separator
power hear just rebuilt ( had it out one time after picking it up)
lower unit rebuilt
fuel pump rebuilt
new voltage reg
new stator
new plugs and wires

still has the old trigger and coils

heres the problem:
I bought the motor on craigslist.. it ran ok, it would top out at 3200 rpm max under load (ran fine on the hose) and not get up on plane.. prop swap didnt seem to change the problem.
I took it in, ended up having to rebuild the powerhead.. new rings, piston heads, seal blah blah. Also re-rebuilt the carbs and fuel pump. the lower crank seal was bad and i ended up boring all three cyls .40 over.
I got it back and finally took it out.. it ran much smoother but still topped out at 3200 rpm at 9.5 mph and wont plane.

any ideas would be appreciated!!!!! thanks in advance!

 

[Beastieboy]

Re: 1999 90hp merc 3 cyl.. no power!!

I know you said had power head rebuilt. I would check compression again. I read thru about all the forums had to offer. Had same issue or similar sluggish. Mine is 650 went and checked compression and it was 135 for 1. 137 on 2 and flat dead on 3. Let me say this it ran fine in drive way. It idled perfect seemed a sweet motor. And even missing a chunk of number 3 piston it still kicked in and when I banked I guess gave that cylinder a lil compression and would start to go like it should have for short stints. Thought it was a fuel problem for 3 weeks. Auto parts store will let you borrow a compression gauge. Or they say rent it for 30 bucks and return money when you return the gauge.

 

[carholme]

Re: 1999 90hp merc 3 cyl.. no power!!

What is the s/n of the engine?

If you have just got the engine back from a shop, did they not do a break in and test run of the engine to determine if it was developing max rpm/full power? One would presume that you have some kind of warranty and if so, I would be acting on that pretty quickly befor attempting any kind of repairs.

Gerry