Hard starting 7.5 Merc?

[steam_mill]

I have a Mercury 75, 7.5 hp from the late seventies(1977?). Canadian serial number is 7106267.<br /><br />It runs well. Idles smoothly and WOT is smoth also.<br /><br />It is difficult to start. Once it starts, it will restart easily. After about <br />30 minutes of rest, it is difficult to start again.<br /><br />Here is what I've tried:<br /><br />1. Checked primer bulb. It pumps gas and gets hard. Pumped while underway. Replaced it. No difference.<br /><br />2. Checked fuel filter. It was clean but I cleaned it anyway.<br /><br />3. Checked plugs. They are new and were clean. Cleaned them and regapped them.<br /><br />4. Treated with Deep Creep. Idles even better now.<br /><br />5. When running, checked for spark. Will run with either plug wire disconnected. Nice blue flame on both plugs.<br /><br />6. No spark when it doesn't start. If I pull the starter over and over and over, it will eventually come to life and run great.<br /><br />It seems by conincidence but if I pull the motor up and drop it, it sometimes will restart.<br /><br />I'm completely stumped. If it were the powerpack, I'm thinking it will either work or not. I can run the motor for 30 minutes and it will start right back up. Wait awhile and it will not start.<br /><br />I'm thinking stator? But the spark is so good when it runs, that I'm not sure about that either.<br /><br />Fishing season is here. I need this to work.....<br /><br />Any ideas?<br /><br />Tx.<br /><br />Joe

 

[Laddies]

Re: Hard starting 7.5 Merc?

Ck and see if it is one of the 7.5 with a 2 peice chohe butterfly the springs on them get weak or break alot. and the choke won't work properly

 

[AndyL]

Re: Hard starting 7.5 Merc?

I may be off the mark here and stand to be corrected but I had an old 7.5 hp merc that would do the same. Can't remember if it was the same era as yours but the fault was traced to the power pack units. I believe there is an earthing wire sticking out of the bases that should earth to the block. If it gets corroded or falls off you have no earth hence no spark generation. These are the units that the end of the HT leads go into. Try removing one and have a look underneath it to see if there is an earthing point. It may not be the same on your motor so treat this as a guess. Eventually I had to replace both power packs and my troubles were over.<br />Andy

 

[steam_mill]

Re: Hard starting 7.5 Merc?

Andy:<br /><br />I'll try that.<br /><br />Appreciate the comment.<br /><br />Joe