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1987 mercury V6 150hp black max

N

Nvandoorne

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So I bought this boat a few years back, full knowing it had a hurt motor.

But I'm stubborn and it was a good deal.
The boat is a 18ft pro craft and it has a 150 V6 merc 2stroke

The motors problem is. When you get the boat in the water (and run the outboard under load) it doesn't have the power to get the boat on plane the best I have ever got was 4000rpm on the tach..


The work I've done is.
-removed the oil injection and set the motor up to run on mix gas.

-Replaced thermostats
-replaced impellar
-rebuilt mechanical fuel pump
-rebuilt carbs with gasket kits
-Rebuilt pop it valve
-

The previous owner had a 2stroke mechanic look at it and he was certain it was a crank seal. But wasn't comfortable doing the repair.

When i take the boat out on the water. I'll hold the choke and the engine just start to bog out almost immediately.

Thanks
 
Spark,compression and fuel,at the right time is what it takes for a engine to run.Did you check your compression,do so and post results,does your spark jump a 7/16 gap on a open tester.Remove your spark plugs and inspect,do they all look the same.
 
Compression is 110 on all cylinders.

Ive replaced all brand new plugs. Tried swapping a new ignition coil in place of each orignal coil.
Made no difference with the outboard.

I’m hesitant to take the power head off and do the crank seals like a previous mechanic said it was the problem.

Mostly because i feel its more fuel related then a vacuum problem..

Correct me if im wrong. But when i have the boat on the lake and i get it up as fast as it’ll run. Ill hold the choke in and it starts to bog

Ive tried priming the fuel bulb. But that doesnt help either
 
Does your spatk jump a 7/16 gap?Do a cylinder drop test,with the motor running pull the plug wires off one at a time and see how the motor responds.
 
The prop is the original that was paired with the motor for that boat from the manufacture. I know the history of the boat. It has less then 100 hrs since new back in 87.


It runs good on the garden hose or with the bottom end in a garbage can.
Tach reads up to 7000rpm when theres no load on the boat.

Once the boat goes in the lake and you are working the motor. It refuses to get up to half power.

Sounds hurt.

But sounds good when testing at home.


All the spark plugs had good spark when i bench tested.
But i havent pulled plugs off while the boat is preforming in the lake..

My only intention for this boat to is burn gas and go fast when i take it out, why I havent bought a newer motor for the boat. But it’s deff coming to that decision time.
Boats been looked at by mechanics over the last 20yrs in hopes of fixing this issue.

Im just the 3rd stubborn owner that is hoping he is the lucky one to fix it.


Which brings me back to the crank seals…
 
I’ve rebuilt the carbs. Rebuilt the mechanical fuel pump.
Replaced the cooling system parts (impellar, both thermostats, and popit valve)

New fuel lines and water cooling lines. Hose clamps on all connections.
Checked the fuel tank that it gets proper ventilation.
No fuel pump inside tank.

Removed direct oil injection system and plugged with the merc delete plug.
Premium fuel mixed at 50:1

New battery cables and inspected wiring.


Previous owner replaced stator and cdi with no luck. I have original parts in my garage.

Like i said. The first mechanic figured it was a crank seal.

From what ive experienced testung the boat on the lake. I would lean to the fuel side. But

When i had a friend pumpin the priming bulb it flooded the engine
And when i push the choke in durring opperation it floods it aswell.

But im out of ideas.
 
Its a fiberglass boat, no leaks that ive found. Stays dry in the below floor storeage.
Previous owner removed the floor and rebuilt it.

Possible the prop could be wrong. But im more inclinded to thinking its mechanics related
 
Nvandoorne said:
I’ve rebuilt the carbs. Rebuilt the mechanical fuel pump.
Replaced the cooling system parts (impellar, both thermostats, and popit valve)

New fuel lines and water cooling lines. Hose clamps on all connections.
Checked the fuel tank that it gets proper ventilation.
No fuel pump inside tank.

Removed direct oil injection system and plugged with the merc delete plug.
Premium fuel mixed at 50:1

New battery cables and inspected wiring.


Previous owner replaced stator and cdi with no luck. I have original parts in my garage.

Like i said. The first mechanic figured it was a crank seal.

From what ive experienced testung the boat on the lake. I would lean to the fuel side. But

When i had a friend pumpin the priming bulb it flooded the engine
And when i push the choke in durring opperation it floods it aswell.

But im out of ideas.
Click to expand...
Hi
I bought a hydro sports 1983 150 mercury black max.
I replaced everything
Stator , trigger, cdi boxes , fuel pump, everything, mine done the same thing, same exact symptons.
You say if you squeeze primer bulb the motor floods .
Does bulb stay tight ? Or does it get soft after a few minutes?
 
What model Procraft as I knew a lot of the R&D guys at Procraft/Astro, HydraSports,Stratos,Bullet, Venture and Ebbtide. Sold and set up & raced a lot of these models
 
Its a 17.8 procraft.
Ski surf boat, real low rider.
Straight windshield across both driver and passanger seat

Not sure on the model of the boat itself. It looks like an older stratos.
 
They all bark and roar on a hose.----7000 in neutral means nothing and can damage the motor.-----Sounds like it is running on 4 of 6 cylinders.-----Mark TDC for each cylinder on the flywheel.----Use timing light to check where each cylinder fires at idle.----And if there is a blocked carburetor you could be damaging this motor.----Stop running it until you determine the issue.
 
I’ve taken a temperature gun while on the water to see if any of the cylinders were cooler then the others…

But were all relatively the same..

Maybe i should go n replace all 6ignition coils..
 
Some 20 years to find a lack of performance issue ???-----Maybe the wrong prop for the boat.----What pitch is the prop ?----Do some testing !!----Does spark jump a gap of 3/8" on each lead , yes or no ?----Does each plug fire at the correct time ?-----Pull plug wires of 1 at a time with engine idling.----Report what happens.-----Reed valves checked ?
 
Nvandoorne said:
I’ve rebuilt the carbs. Rebuilt the mechanical fuel pump.
Replaced the cooling system parts (impellar, both thermostats, and popit valve)

New fuel lines and water cooling lines. Hose clamps on all connections.
Checked the fuel tank that it gets proper ventilation.
No fuel pump inside tank.

Removed direct oil injection system and plugged with the merc delete plug.
Premium fuel mixed at 50:1

New battery cables and inspected wiring.


Previous owner replaced stator and cdi with no luck. I have original parts in my garage.

Like i said. The first mechanic
Click to expand...

Nvandoorne said:
And the primer bulb stays firm to squeeze while the motor is running.
Click to expand...
With motor off

Start by removing the carb silencer cover push trottle wide open and look into each carb one at a time while squeezing the bulb and see if gas is running out of any of the carbs.
Mine was on the verge of flooding all the time due to a leaking float needle , I had rebuilt carbs and dissasembled them a few times after changing everything.
Went from 35 to 53 mph.
Squeezing the primer should not make it flood out unless something is leaking, carbs , fuel pump diaphram.
Can you post a pic of fuel pump and the carbs?
 
Should be a 20P Turbo or 21P Quicksilver..That is not a hull for speed, that why they are nicknamed "Slowcraft". Good ride but not fast
 
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