20 Most Recent Mercury Mark 75 Outboard Boat Motor (Mercury Marine) Questions & Answers

Looks like this;
Product Line Year H.P. Model Number Model Description MERCURY 1985 7.5 1007205 7.5 /9.8 H.P.

Mercury Mark 75... | Answered on Jun 09, 2019

Good Morning John,
Please replace The fuel Pump Diaphragm.
It Comes In a Kit Should solve Your Problem But needs To Be Replaced If It Hasn't Already Been Done,
It will be a good starting Point to solving Your Problem.
Regards Gordy

Mercury Mark 75... | Answered on Mar 14, 2019

Good Morning,
From What you have Explained This Is Normal The cooling System Is Joined To the exhaust System So Water Will Come Out through the Exhaust And Pass Through the Proppeller.
Hope This Helps You

Mercury Mark 75... | Answered on Mar 14, 2019

Good Day
The Carburettors Need Servicing And float Levels Adjusted correctly

Mercury Mark 75... | Answered on Nov 02, 2017

Sounds like the impeller in the lower half of the gearcase is dead. Find a qualified technician.

Mercury Mark 75... | Answered on Nov 06, 2014

pending on how old your engine is coz the price of the full system is lots and mite be more than what your engines worth so check on price of engine with it fitted !

Mercury Mark 75... | Answered on May 29, 2014

Take out filler plug and turn upside down

Mercury Mark 75... | Answered on Oct 05, 2013

Most of those early 6cylinder mercks were dual coil fired on a dual points system with one coil firing 3 cylinders and the other firing the remaining 3 cylinders. They later came up with an electronic IR shutter system for running a switch box. Neither system was something for the average back yarder to be fooling with. The belt drive was critical for clearances and settings.

SO- check to see if it has power to the ignition (about the only thing you can fix) and if it does- find some old timer Mercury guy to fix it for you.

Mercury Mark 75... | Answered on Oct 11, 2012

That serial number was produced during the years of 1988 through 1990.

Mercury Boating | Answered on Oct 21, 2019

Take out the spark plug. Hold a drinking straw up to the spray nozzle and shoot the fog into the spark plug hole.

Mercury Boating | Answered on Sep 30, 2019

Depends on the HP of the motor. The long shaft will only ad a few lbs. See this link for motor specs on weights.


Mercury Boating | Answered on Sep 25, 2019

Best not to do it as you will get maybe 2 mph. Also, I believe it is ******* to modify 1996 and later motors.

Mercury Boating | Answered on Sep 09, 2019

That cylinder isn't firing. Bad plug, or no spark to that cylinder. Swap the plug to another cylinder and check again. Then swap the coil to another cylinder.

Mercury Boating | Answered on Aug 22, 2019

Wow, a 40hp is FAR too small for a 16 foot anything except a bare aluminum Jon Boat with one person and a tank of gas!

90 to 110 hp is the recommended. I was guessing 70 to 90.


WOT is normally 5000 to 5,500 WOT, but yours is struggling with the weight. There should be a coastguard regulation sticker in the boat with the Max HP that hull can take. You should have that motor or 10hp less.

The manual indicates 5,000 rpm for timing.


Mercury Boating | Answered on Jul 24, 2019

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