Mercury Black Max Problems

[Asmikle1]

I have a 1988 Mercury Black Max 175 that is Hard to start. I once started it wants to stall but it I give it gas and throw in gear it will run. Last few trips it is slow on acceleration but few seconds later it catches up and will run WOT. At the end of the day while trolling back to the dock the an alarm under dash sounded (constant tone) so I turned off and used the trolling motor to get to dock. Before last trip I changed the spark plugs, fuel filter, fuel pump diagram, cleaned the carbs (all three). Not sure what the problem is. No oil VRO so I use mixed fuel 93 octane. I ran a compression test and average 108 to 110 psi.

 

[Dukedog]

jus start this?.. always been "hard ta start"? when its cold and/or anytime? can be a number of things.. enrichner workin'?.. have you changed/altered linkage any?.. timin' any?.. alarm is over heat.. probably time for a pump "kit"..

 

[Chris1956]

Constant alarm is probably overheat. So rebuild water pump with a new impeller, wearplate and 2 gaskets. If lower part of pump is melted, replace that as well. If upper part of pump is melted or cracked, replace it.

Check and test thermostats. They do wear out.


Retest operation of motor with fresh fuel mix.

 

[Asmikle1]

Okay. I will start by replacing the impeller and housing. Also check into the thermostat. The motor has been hard to start for a while.

 

[Dukedog]

when you say "cleaned" tha carbs did you use same gaskets or replace ALL gaskets with new ones?.. no mater how/what tha carb gaskets (inside and out) look like they need to be replaced with new when carb is disassembled for any reason......

jan.. all wh series (whats on your motor) carb gaskets are tha same...

 

[Asmikle1]

I finally was about to take the three carbs off, clean them, and soak in carb cleaner. I also replaced all gaskets on then and the needles (all six). I did notice that the Jet is missing (#2 on photo attached) on all three carburetors. I dont know why the last owner took them off. Im looking into ordering six part# 1395-6247 (Amazon) Jet 0.090 but not sure if they are needed. Can these not being installed cause excess fuel from carbs when running or poor idle / hard start?

 

[Faztbullet]

Nope and most carbs dont have em