mercury 1991 75hp

[msn26753]

Sorry I dont have serial number handy right this second but I have a friend that just bought used mrcury 75.. it was acting kinda funny on the water kike it wasnt getting gas.. he noticed it was leaking alit if gas.after hooking to muffs and fired her up , we noticed it was leaking alot of gas. The tube from the enricher to the back of the carb seems to be leaking badly. We are going to change this line. I dont know if this is a vent line or fuel line. Im asduming fuel since its keaking gas from where it neets the back of carb. Does this sound like why it might be having some issues running. And what exactly is the enricher for. He stated that the oil injection diesnt work so hes mixing his gas... any help woild be awesome.. thanks

 

[CharlieB]

It takes a lot of fuel to make a lot of power. ANY leaks in the fuel system is a BAD thing. Replace hoses if need be.

With the motor level and not running, pump up the primer bulb and hold it like a firm handshake while looking for any other fuel leaks. Open the throttle and look down the carb throats to see if any fuel is leaking inside. If so then order carb kits, clean and replace the needle and seat, be sure to adjust the float height correctly and identical on all carbs.

Next disconnect the fuel hose to the carbs, crank the motor and see that you have a nice fat pulse stream of fuel, any less is a problem, maybe need to rebuild the fuel pump. Reconnect the fuel hose but add a piece of clear hose so you can watch the fuel go thru. Start the motor and watch the hose, if you see any air bubbles passing by then you know there is air leaking INTO the hoses somewhere between the fuel pump and the tank pickup tube. Find that air leak and seal it as this will not allow the fuel pump to keep the top carb full while at WOT and burning lean will melt that top piston.

Oh, be SURE to remove that clear hose once finished with repairs as it is NOT fuel rated nor approved for fuel use, only short term testing.

These few things will go a long way in helping to keep your motor relialble.

 

[Texasmark]

The clear hose is available at Lowes in the plumbing dept. Fuel takes the plasticizer out of it and it gets stiff which can leak over time. I believe it's 5/16" diameter. If I boats doesn't sell replacement hoses there are other sites on www that do if you don't have a Merc dealer handy. While you're at it, if you haven't replaced your OEM gray gas line from the tank do that too with a new squeeze bulb. They degrade over time and the inside flakes off and gets into your fuel line and clogs things up. Mine failed at 10 years.

Mark