Just joined this forum today. Searching for info.
I have an older boat with a 75 hp 4 cylinder Mercury Mariner engine.
I purchased the boat from my Father, & he purchased it new in mid to late 80's. It hasn't seen much use in 30 years, & was stored inside. Possibly never used at all some years, & maybe 4 or 5 tanks of gas on other years.
The engine seems to run great on the muffs in the driveway. It fires right up, instantly once warmed up, but it stalls at idle, & won't troll at low speeds, when out on the lake.
I have bypassed the oil injection, & been mixing 2 cycle oil at 50:1
Seems hard to find any info on these larger horsepower Mercury Mariners.
Carbs were removed, & found that the air fuel mixture screws were not set equal.
top carb was screwed out 1 full turn, bottom carb was screwed out to almost 1.75 turns.
Any idea where the screws should be set.
Heard that they behave differently when adjusting with muffs than when actually on the lake.
I cant find a model number, on my motor but there is a Mercury SN starting with Letter A, & 6 digits.
Spark plug currently in it is an Autolite 2872.
I am not sure if it uses a resistor or or inductive resistor.
I believe that the correct plug should be a NGK BUZHW-2, & that they have been discontinued.
Not sure how important the Inductive resistor is, & if it could be causing problems, or more likely my air fuel mixture screw being out of adjustment.
I plan on taking a screwdriver & trying to adjust the air fuel mixture on the lake.
Canada Day Stat holiday tomorrow, so hoping someone has some info for me.
Thanks
Calvin
I have an older boat with a 75 hp 4 cylinder Mercury Mariner engine.
I purchased the boat from my Father, & he purchased it new in mid to late 80's. It hasn't seen much use in 30 years, & was stored inside. Possibly never used at all some years, & maybe 4 or 5 tanks of gas on other years.
The engine seems to run great on the muffs in the driveway. It fires right up, instantly once warmed up, but it stalls at idle, & won't troll at low speeds, when out on the lake.
I have bypassed the oil injection, & been mixing 2 cycle oil at 50:1
Seems hard to find any info on these larger horsepower Mercury Mariners.
Carbs were removed, & found that the air fuel mixture screws were not set equal.
top carb was screwed out 1 full turn, bottom carb was screwed out to almost 1.75 turns.
Any idea where the screws should be set.
Heard that they behave differently when adjusting with muffs than when actually on the lake.
I cant find a model number, on my motor but there is a Mercury SN starting with Letter A, & 6 digits.
Spark plug currently in it is an Autolite 2872.
I am not sure if it uses a resistor or or inductive resistor.
I believe that the correct plug should be a NGK BUZHW-2, & that they have been discontinued.
Not sure how important the Inductive resistor is, & if it could be causing problems, or more likely my air fuel mixture screw being out of adjustment.
I plan on taking a screwdriver & trying to adjust the air fuel mixture on the lake.
Canada Day Stat holiday tomorrow, so hoping someone has some info for me.
Thanks
Calvin