83 Merc 50hp-barely does 15mph--

[jfrost1920]

Hey guys. This is my first boat and first motor and Im at a loss. I have a 16ft 1985 Monark bass boat. It has an 83 merc 50hp motor. With just me and 1 battery and a half tank of gas, no gear to say, will only run about 20 or so mph. Thats a good day. sometimes I cant get it above 12 and barely on plane. My dad has an 01 merc 50hp and his will do 30-35 pretty easily. With 3 guys in it!!! and all their gear!!! Thats my first question.

My second is that the motor dies now when I put it into gear. Not right off the ramp but after awhile of fishing it has a bad time. It will start, but when I put any throttle on it, it dies. then its real hard to get started again. It will run fine until the next time I have to start it. I always get it going but sometimes it takes 10mins or so and its scary at night when your far from the ramp. . Its got 125 compression on all cyl. new plugs, fuel lines to the motor and primer bulb. clean fuel filter. What could be wrong with this?

 

[MercBravoIII]

Re: 83 Merc 50hp-barely does 15mph--

check the spark, if its good then i would move directly to a plugged up carbuerator. it sounds to me like the carb though, the hard start is defenitly a key idication, you can get it rebuilt or cleaned, your choice, check your spark first, if so make sure the fuel gets to the carb, if it does then most likely have a clogged carb

 

[Barnacle_Bill]

Re: 83 Merc 50hp-barely does 15mph--

If the motor has sat for quite a while before you got it you need to read this.
http://forums.iboats.com/showthread.php?t=158086

 

[jfrost1920]

Re: 83 Merc 50hp-barely does 15mph--

Thanks. It looks to me like their might be some fuel leaking from where the lines go to the carbs. The fuel lines go from the filter to the carbs and then split--one for the top and one for the bottom carb. Right at the T is where it looks like the leak is coming from. Its enough wherever its leaking to pool up in the bottom of the motor underneath the carbs. and saturate all the wires and hoses with fuel/oil mix. heres some questions.


Question 1: Would this alone cause the problems im having?
Question 2: What kind of clamps do I use on the new fuel lines if i switch them?
Question 3: Can I just spray some automotive carb cleaner in the carbs? Either spray it in and let it sit or spray it in while its running?

I can trim a house or operate a PATRIOT missile like a pro but when it comes to car/boat motors I dont know anything!! Thanks alot guys

 

[bigred69]

Re: 83 Merc 50hp-barely does 15mph--

#1 Possible but not likely. Sounds like idle circuit in carbs are gummed up.

#2 If the hoses are not soft and pliable. Replace them. A hard line is not easy to reseal once it starts leaking. Zip ties can be used for clamps. their are special ones that can be purchased for fuel hose.

#3 No. The carbs must be disassembled and all of the tiny passages cleaned and inspected.

 

[jfrost1920]

Re: 83 Merc 50hp-barely does 15mph--

So me being smart enough, just not experienced enough, can I take the motor apart and clean and rebuild my carbs myself? I have a manual for the motor. Is it something that if I take my time and take pictures, I could get it apart, cleaned and rebuilt without much trouble? Or is this something I should definately seek profession guidance for? Ive been looking at it and Im not really sure if this is in an amatuers skill level. I just need some people to either say go for it or youll do more damage and will cost more than if you just have a pro do it. THanks alot.

 

[jfrost1920]

Re: 83 Merc 50hp-barely does 15mph--

When I squeeze the primer bulb, gas was leaking Major where the fuel line goes into the top carb. There is like a swivel adapter for the fuel line to connect to the carb and i just tightend the screw on that. Instantly stopped the leak. Now you can squeeze the primer and nothing happens. unless you squeeze it really hard and alot. Then gas shoots out the bottom carb, out of the butterfly valve in the front. But only when I squeeze it really really hard. Any ideas. Thanks for the help