Mercury classic 50 fuel issues

[JCFERG]

1989 classic 50, 45 hp mercury, 4 cyl. 2 carbs.
The problem is that the motor starts right up and idles smooth, runs good, but will not go over 2400 rpm while in gear.

While trying to solve a possible fuel issue i tried spraying sea foam in the carbs while the motor was idling. According to the directions on the can, I was spraying sea foam into the high idling motor (1500 rpm).

Something I noticed and could be part of the problem is when I sprayed the sea foam in the lower carb I could spray for 20 seconds and just notice a slight drop in rpms. While spraying sea foam in the upper carb, the motor choked out and died within 2-3 seconds of spaying the cleaner. I was spaying the cleaner directly into the carbs using the straw adapter, putting the straw adapter past the butterfly choke.

Why are the carbs acting differently while spraying the sea foam? I think this might be related to the problem.

 

[huntxtrm]

Re: Mercury classic 50 fuel issues

same thing is wrong with mine. I tore the carbs down, there was a piece of old cork gasket from one of the bowl gaskets lodged in one of the jets. put it back to gether ran fine. I'm in the middle of a complete carb rebuild right now. I have the exact same motor just mines a 86 model. good luck. carbs are kindofa pain to get off. you gota remove the starter, then the front plate on the motor. be sure and unhook your battery first so nothing fries. Not that bad once you do it. Good luck. oh and if you get the kits and your carbs are the ones with the integral fuel pump built on the side. make sure they give you the kit with the fuel pump diaphram in it. might as well change it all while you have it apart. i have the diagrams for the carbs if you need them. with the bench adjust procedures. pm me if you need them. good luck.

 

[huntxtrm]

Re: Mercury classic 50 fuel issues

Just to let you know, i fired mine up. that fixed the problem. Also search threads started by clams canino. he posted a killer step by step on syncin these older motors. I did mine, i believe that helped also. good luck.

 

[zorak]

Re: Mercury classic 50 fuel issues

Check compression and ignition for spark on all 4 cylinders.It might be a problem with the carb but i feel its probably ignition related.If it is do a search on this forum as myself and several others had had similar issues with either a classic 50 or a similar engine.

 

[hdman97]

Re: Mercury classic 50 fuel issues

same thing is wrong with mine. I tore the carbs down, there was a piece of old cork gasket from one of the bowl gaskets lodged in one of the jets. put it back to gether ran fine. I'm in the middle of a complete carb rebuild right now. I have the exact same motor just mines a 86 model. good luck. carbs are kindofa pain to get off. you gota remove the starter, then the front plate on the motor. be sure and unhook your battery first so nothing fries. Not that bad once you do it. Good luck. oh and if you get the kits and your carbs are the ones with the integral fuel pump built on the side. make sure they give you the kit with the fuel pump diaphram in it. might as well change it all while you have it apart. i have the diagrams for the carbs if you need them. with the bench adjust procedures. pm me if you need them. good luck.

Unlike the 86 I think the 89 has a seperate fuel pump, not on the carbs.