73 merc 150 stalls when engaged in gear

[gumball]

I have a 1973 merc 150 which dies if the idle is set where it is supose to be i have to raise the idle up to about 1100 so the motor will not stall but i hate that due to the slamming in gears, i had a tune up done 2 months ago at our nearest boat shop. but the problems still persists, the only thing i have done to the motor is put a new water pump in and that was done before the tune up. the engine runs fine at wot and normal idle but when u put it in gear it dies. please help. if you need any more info please let me know.

 

[gumball]

Re: 73 merc 150 stalls when engaged in gear

the inline 6 has great compression on all cylinders also, runs like a champ just not when engaged in to a gear. could this have anything with the spark advance?

 

[Clams Canino]

Re: 73 merc 150 stalls when engaged in gear

Do a search on this forum for a post I did. Search on "timing and synch". Get a $20 timing light and run through the whole process. make sure your carbs are clean and that all 3 idle needles have the proper effect when adjusted.<br /><br />Make sure it's propped to make better than 5500 WOT. Too much prop can make it hard to put in gear too.<br /><br />Once you are SURE nothing is wrong or misadjusted. It comes down to old and tired reeds and reed blocks. Try to get it to idle down at least under 1000, then master the art of bumping the throttle a moment as you stab it into gear - to get it over the hump. If you've got one that has to idle a little high, use an aluminum prop to minimise lower unit abuse.<br /><br />Also use a can of Mercury Power Tune as directed to eliminate any sticky rings.<br /><br />-W