79' Mercury 115

[Dassault]

I have a 1979 merc 115 outboard. I use the boat for skiing only. The boat does great most of the time during the wholeshot. But a good 50% of the time the engine will hesitate or miss. I have adjusted the idle mixture numerous times. I replaced the ball and pump diaphragm, but i did not replace the check valves, could this be the problem. Replaced spark plugs also. 50:1 mix with super premium full and quicksilver. Any suggestions?

 

[Laddies]

Re: 79' Mercury 115

Ck the pluse line hoses on the fuel pump some were missing the internal springs and the lines collapes as they get older and don't punp well at idle--Bob

 

[Dassault]

Re: 79' Mercury 115

I did replace the pulse lines with normal automotive lines, but i did not place a spring in the line. I would think that they would be strong enough being new. I have replaced all fuel lines. Maybe i need to replace the jets and seats.

 

[Dassault]

Re: 79' Mercury 115

May just have to rebuild the carbs. Cleaned top and bottom carb last season. We'll see

 

[Clams Canino]

Re: 79' Mercury 115

That and make sure it's warmed up - with no thermostat they cool off FAST... <br /><br />-W

 

[Dassault]

Re: 79' Mercury 115

Well, I run the boat at about 3600 when skiing so it must stay warm. I turn around, try to go again and the boat stalls. I take off to clean out the plugs and it works again. Couple times later, it hesitates yet again. Why?!?! It is not consistent, this is weird.

 

[Dassault]

Re: 79' Mercury 115

How could it cool of in a minute or so.

 

[Clams Canino]

Re: 79' Mercury 115

If you have to clean the plugs it's prolly a carb issue. A minute or two of trolling CAN cool one of these beasts off a lot though. <br /><br />-W