1987 90hp merc

[capt silverton]

I have a 1987 90 hp merc motor that I have had checked out a couple of times and have been told it runs great and compression is good on all cylinders. The problem it gives me is while underway I can not get on plane it rev's up as if the prop is spun until I lower rpm's and then it continue at slower speed. Prop has been changed twice, is there something else I should be looking at?

 

[racerone]

Measure the transom height.-----Motor might be mounted too high.

 

[capt silverton]

I have a 1987 90 hp merc motor that I have had checked out a couple of times and have been told it runs great and compression is good on all cylinders. The problem it gives me is while underway I can not get on plane it rev's up as if the prop is spun until I lower rpm's and then it continue at slower speed. Prop has been changed twice, is there something else I should be looking at?

Mercury Marine Tech Forum | I have a 1987 90 hp merc motor that I have had checked out a couple of times and have been told it runs great and compression is good on all cylinders | Facebook

I have a 1987 90 hp merc motor that I have had checked out a couple of times and have been told it runs great and compression is good on all cylinders. The problem it gives me is while underway I can...

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[racerone]

Is this a 3 cylinder motor ?---Or inline 6 ?------Stop running this motor until you sort this out.----A plugged carburetor leads to serios damage.-----Wrong prop ?----Water logged hull?-----How did it run for you last season?

 

[capt silverton]

Is this a 3 cylinder motor ?---Or inline 6 ?------Stop running this motor until you sort this out.----A plugged carburetor leads to serios damage.-----Wrong prop ?----Water logged hull?-----How did it run for you last season?

Yes it is a three cylinder, I have had a shop check the motor out it runs good until you put a load on it, compression is good, prop has been changed and is correct. Check out the video. It acts as if the prop is spun but it is new.

 

[fitz73222]

looks like a 1984-1985 6 cylinder in the video

 

[racerone]

See post #2 ----Or do you not want to answer the question?

 

[capt silverton]

See post #2 ----Or do you not want to answer the question?

I'll have to check on that measurement I don't know it's height. Also the serial number is # A149919 to be accurate on the motor.