Merc 1250 (1969) stalls when throttle opened

[buttsm]

Can somebody please help me with my engine problem?<br /><br />Motor is a 1969 Mercury 1250 with thunderbolt ignition. It runs fine for about 15mins, then it will stall when I put it into gear and open the throttle.<br /><br />What I have done so far is:<br />- Had carbs stripped, cleaned and synchronised<br />- replaced plugs and leads<br />- replaced distributor, reset timing<br />- replaced fuel tank and lines<br />- replaced forward control and wiring harness<br /><br />I had somebody tell me it moght be the coil getting hot, and failing, but I don't know how to test for this.<br /><br />Also, the tacho no longer works - but that might be a separate issue.<br /><br />Can anybody help?<br /><br />thanks

 

[Clams Canino]

Re: Merc 1250 (1969) stalls when throttle opened

If your tach lead is picked off from one side of the stator, it means the rectifier is blown. If it comes off the switchbox, it means either the swithbox, tach, or wire has an issue.<br /><br />If it's the former, that means your battery is not charging and a low battery might cause the failure you speak of as the ignition runs off the battery.<br /><br />If it's the latter, your switchbox MIGHT have issues.<br /><br />You say it runs fine for 15? Does that mean you can start it, warm it up for 5 and go out and run WOT for 10 before it fails?<br /><br />-W

 

[buttsm]

Re: Merc 1250 (1969) stalls when throttle opened

thanks for that.<br /><br />The tach runs off the switchbox. <br /><br />I've replaced the rectifier and battery also. Not sure how to check to see if the battery is charging though.<br /><br />The thing runs as it should for 15mins, idles, cruises, WOT, pulls skiers out - then it mucks up.