McRider1962
New member
I am new to forums, please forgive my ignorance to rules or places this should be posted...
Please help!!!
I have a 1984 Mercury OB 75HP 4cyl; Ser#6503669.
History: bought used boat 2 months ago. I knew it needed a lot of work. I rebuilt carbs; new fuel lines all the way to tank (built-in); cleaned out tank vent; rebuilt triangle fuel pump; replaced wires and plugs; 1 & 2 cylinders were not firing and figured out it was the switchbox (replaced) all 4 cylinders firing strong. I set timing best I could based on information that I reasearched. All 4 cylinders have 140 PSI of compression +/- 5PSI
My motor starts easy and runs great on the trailer, in fwd; neutral; and reverse.
Here is my problem:
As soon as I put it in the water and put it in gear it dies. I was able to mess with the screws and idle bolt enough to get it to sort of idle. I was able to finally throttle up but it is not running correctly...acts like it is starving for fuel. I had to run the two low speed mixture screws about 2 or more turns to get it to idle under load. It almost acts like something is binding and holding back from idle or powering up.
I also replaced water pump and seals in the lower unit (oil looked like milk).
Where do I go from here? A "local" mercury guy says my motor is just worn out. I just can't believe with that much compression, it is "worn out" and not worth fixing??
Suggestions?
Comments?
Cures?
Thanks
Greg
Please help!!!
I have a 1984 Mercury OB 75HP 4cyl; Ser#6503669.
History: bought used boat 2 months ago. I knew it needed a lot of work. I rebuilt carbs; new fuel lines all the way to tank (built-in); cleaned out tank vent; rebuilt triangle fuel pump; replaced wires and plugs; 1 & 2 cylinders were not firing and figured out it was the switchbox (replaced) all 4 cylinders firing strong. I set timing best I could based on information that I reasearched. All 4 cylinders have 140 PSI of compression +/- 5PSI
My motor starts easy and runs great on the trailer, in fwd; neutral; and reverse.
Here is my problem:
As soon as I put it in the water and put it in gear it dies. I was able to mess with the screws and idle bolt enough to get it to sort of idle. I was able to finally throttle up but it is not running correctly...acts like it is starving for fuel. I had to run the two low speed mixture screws about 2 or more turns to get it to idle under load. It almost acts like something is binding and holding back from idle or powering up.
I also replaced water pump and seals in the lower unit (oil looked like milk).
Where do I go from here? A "local" mercury guy says my motor is just worn out. I just can't believe with that much compression, it is "worn out" and not worth fixing??
Suggestions?
Comments?
Cures?
Thanks
Greg
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