Help for problem with Merc 75

darnold

Seaman Apprentice
Joined
Jun 30, 2001
Messages
30
I have a mid 70's 7.5 hp Merc which I bought used a couple of years ago. After I replaced the plugs and water pump it ran well until the 2nd time out this season when it stalled after slowing down after a couple hours of intermittent running while fishing. All attempts to restart have the motor starting then dying. The fuel line bulb pump is soft after this happens and the engine restarts after bulb is pumped,only to die again. Seemingly a fuel problem. Filter is clean. I think that I probably need a new fuel pump (it is built into the carb). I have taken the carb off and there isn't any problem with the fuel pump diaphragm that I can discern. I found a small leak in the fuel hose going to the carb. Any suggestions or insights. I am not a mechanic but am a sort of do-it-yourself sort. I am wondering if I should rebuild the carb (the kit costs almost $60) or get new gaskets for the carb (haven't located a source yet) or get it to an outboard mechanic or use it as a mooring anchor (just kidding, it is a great old engine, but I guess there is a limit to how much more $ I want to put into it.<br />I just found this board and am very impressed by the knowledge and generous sharing of it which occurs here! Thanks for any ideas on this.
 

Bear

Lieutenant Commander
Joined
Mar 1, 2001
Messages
1,627
Re: Help for problem with Merc 75

"I found a small leak in the fuel hose going to the carb."<br />Get a new fuel hose and try again. If fuel is leaking out, air is leaking in when the engine is runnig.<br />She is worth that much anyway, right?
 

darnold

Seaman Apprentice
Joined
Jun 30, 2001
Messages
30
Re: Help for problem with Merc 75

Thanks. I have replaced the fuel hose and taken the carb off the engine so I need to get a new gasket kit or rebuild the carb entirely. I guess that is probably what I will go ahead and do. Any words of advice on the rebild process would be much appreciated.
 

darnold

Seaman Apprentice
Joined
Jun 30, 2001
Messages
30
Re: Help for problem with Merc 75

An update. I rebuilt fuel pump (which appeared ok, anyway) and replaced fuel line and put carb back on engine. Carb appeared clean. Problem persisted until I just allowed it to run at high speed and backed off idle needle then reset it. Problem got much better. Then ran engine while using carb cleaner shot through throat. Engine runs great now!
 
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