My boat run slowly. 120HP,2.5L,1989

[liusigou]

My engine can run with maximum speed of 33 miles a week ago. But it run rough with maxinum speed of less than 10 miles yesterday. What happened my engine?

 

[alldodge]

My engine can run with maximum speed of 33 miles a week ago. But it run rough with maxinum speed of less than 10 miles yesterday. What happened my engine?

We don't know, your going to need to do some testing

Suggest
Do a compression test

How long have you owned the boat?

 

[liusigou]

Today I did a cylinders pressure testing. They are 130, 130,100, 130. Last year the third was 120. Can it be fixed?

 

[alldodge]

Not bothered by the one at 100, could be anything and not really be a factor when running

That said, if your gauge is accurate then the motor may just be getting tired

Is the timing set correctly, is timing advancing and if so how much?

How do the plugs look, all the same or different?

 

[liusigou]

They are nearly the same. I only took pics of three.

 

[dubs283]

First two plugs are the same, third is different

When was the last full tune up?

 

[liusigou]

I replaced the gasket of timing distribution which led to the invalid of timing. Then I redo the timing and it works. Should I reset the timing?

 

[liusigou]

First two plugs are the same, third is different

When was the last full tune up?

Yes. The third plug was loosen when I was in the lake last fall. And I bought one and put it back. Then it works. I owned this boat for four years. And have not yet had it tune up

 

[kenny nunez]

How much slop does the rotor shaft in the distributor have?

 

[alldodge]

I showed these to pics to the wife and she has never done any motor work and she sees a difference

 

[liusigou]

Should I replace all the spark plugs?

 

[alldodge]

Should I replace all the spark plugs?

I would
MR43T

 

[liusigou]

How much slop does the rotor shaft in the distributor have?

Do you mean there are some mud in the head of spark plug?

 

[liusigou]

Ok. I will replace the spark plug tomorrow and run it again

 

[alldodge]

How is the distributor cap and rotor?

 

[liusigou]

Are they ok?

 

[liusigou]

I have replaced the spark plug and motor runs more smoothy. Thank you everyone.

 

[nola mike]

First two plugs are the same, third is different

When was the last full tune up?

They are nearly the same. I only took pics of three.

Do either of you see an electrode in #1? Assume that's what AD was pointing out?

 

[dubs283]

I do not

Possible that was a reason for poor runnability

Based on the other pics of cap, rotor, points, etc I'd say OP is due for a full tune up

 

[Scott Danforth]

lots of oil on the plugs - that indicates blowby
the one plug is missing its electrode indicting
there are bits of aluminum on the electrodes indicating the timing is off
being points, you have to set dwell before you set timing. so file the points, set dwell to about 30 degrees, then set timing.