1979 150 Mercury Hard to start

[Shadoe]

1979 150 hp Mercury is hard to start, but runs fine after starting. Starts back good for five or ten minutes after shutting off. 15-20 minutes later is as hard to start as it was the first time.

 

[bmurray]

Re: 1979 150 Mercury Hard to start

check to see if the primer bulb is staying hard. If not replace it.

 

[kevlar3000]

Re: 1979 150 Mercury Hard to start

Is that a V6 or an lnline? I replaced the Stator in mine this spring for the same reason. It will either come down to weak spark, or fuel problems. Run good gas and oil, make sure all fuel lines are in good shape. Rebuild the fuel pump, a very easy 10 buck job you can do in 15 minutes. Have you had the carbs rebuilt recently? Needle valves, stuck floats, can all be a problem. How is the engine as a performer? You should be running at least 5500-5800 rpms to keep that engine happy. Anything lower usually likes to eat your pistons. Have you done a compression test on that motor? If it is tired she won't hesitate to let you know. <br /><br />I have no idle or starting probs now that the spark is nice and strong. Start on the obvious stuff and move on from there.

 

[Shadoe]

Re: 1979 150 Mercury Hard to start

We've replaced the spark plugs, the others were fouled terribly. Am changing the fuels lines, put a new primer bulb on it, but its not staying hard for some reason.<br />After replacing the spark plugs it hit on the first crank but I haven't tried it out yet. The boat has been sitting for years, with no use. It may have had bad gas in it, I drained it.<br />The marina said it sounded like a dirty carb.<br />I'm working on it, and greatly appreciate your help.

 

[kevlar3000]

Re: 1979 150 Mercury Hard to start

I would definately rebuild those carbs. You may have a stuck float. Old gas will do everything it can to eat your engine so I would get that out of the tank. Don't run her hard until you get the fuel flowing right. Fuel starvation ( plugged jets ect) is agony on those old pistons. My guess is you have more fuel related problems than spark, just a hunch.

 

[kingdingy]

Re: 1979 150 Mercury Hard to start

On my mercury, I have to hold the choke button down while I turn the key or else it wont start. $100.00 at the boat mechanics shop told me that. Thought that might be relevant here.