1995 Force 120 slow to get on plane

[the_dude]

Last trip out on my way back from the fishing grounds (about 10 miles) boat felt sluggish getting on plane, and would only top out around 28 mph, usually about 10 mph faster. I just took it out today and same thing. Fuel efficiency seems down as well. Boat feels very slow and sluggish to get on plane with not much top end speed / power. Any ideas?

 

[Jiggz]

Any signs of misfiring, i.e. idling lower than used to be? Shaking or stalling when placed in gear unless you slam the throttle? What is WOT rpm? Throttle in full horizontal at WOT? Heavy smoke? In short, need more symptoms to have an accurate diagnosis.

 

[roscoe]

Sounds like you are only using 3 of the 4 cylinders.


Compression check all cylinders.
Do you have spark on all 4 spark plugs?
Are you getting fuel to all 4 cylinders - inspect spark plugs.

Some possible causes:

Loss of compression could be broken rings, scored cylinder, or a leaking head gasket.
lack of spark could be a bad wire, bad coil, loose sparkplug wire.
No gas to a cylinder could be carb or reed valve issue.

 

[jerryjerry05]

Do the cyl. drop test.
Start the motor, pull the plug wires one at a time, replace..
Any difference?
Compression/spark test.

 

[the_dude]

Any signs of misfiring, i.e. idling lower than used to be?

low speed idle seems the same as always, fine

Shaking or stalling when placed in gear unless you slam the throttle?
No, just sluggish and lack of power. It used to go from no throttle to wide open quick, like fast enough to pop a water skier up. Now it's like 30 seconds it seems until I'm on plane.

What is WOT rpm?
I don't have an rpm gauge connected. Doesn't sound overworked but that's just a guess.

Throttle in full horizontal at WOT?
Full horizontal yes.

Heavy smoke?
No smoke at all


In short, need more symptoms to have an accurate diagnosis.

 

[the_dude]

Whats the easiest way to check compression? Is that where I should start? I'd like to start with the easiest fix and moving up if that makes sense.

 

[the_dude]

Plugs are fairly new, maybe 5-6 trips. Wires aren't.

 

[racerone]

Post your compression test numbers.----It is the easiest / most important step in trouble shooting.

 

[the_dude]

I'll try to figure out how to do that. Thanks guys

 

[the_dude]

well, I think this is bad. The second cylinder down has no compression. Other three read 90.

 

[Jiggz]

The next move is to remove the head and inspect the cylinder in question.

 

[roscoe]

With any luck, its only a head gasket.

fingers crossed.

 

[the_dude]

Second cylinder down.

 

[the_dude]

and another pic

 

[racerone]

Gasket is blown I think.-----But there are other serious problems judging by the top piston.-----This motor needs to be torn down for inspection.

 

[the_dude]

1 - 4, 1 being the top cylinder

 

[the_dude]

Gasket is blown I think.-----But there are other serious problems judging by the top piston.-----This motor needs to be torn down for inspection.

Do you say that because of the pitting or whatever that is at the end of the piston?

 

[the_dude]

I should probably mention two of the bolts were broken when I removed the head.

 

[racerone]

This motor has a few problems.----The marks on the # 1 piston look expensive to me !!

 

[Jiggz]

I hate to say this but that motor is in a very rough shape. First, the top cylinder has some scouring on it and the piston crown is in rough shape. Looks like lack of lubrication and overheating.

The #2 cylinder has gouges and at the same the piston has indication of rings catching on the exhaust ports. Cannot tell how deep the gouges are from the pics but it looks like it's still salvageable.

Definitely needs to pull out the both pistons and make further assessment on the gouges. For sure both piston and rings needs to be replaced and both cylinders to be honed at least, if not machined.