Hard start and half throttle

[Dick Bacon]

I have a 1988 Mercury 70hp three cylinder. When started cold, I have to crank a long time to get started. Then when started, I can only get about half throttle when throttle is pushed all the way. This will continue for about 10 minutes. The motor will start to surge back an forth like it wants full throttle. Sometimes the alarm will go off.Then, all by itself, full throttle kicks in and its fine for the rest of the day. Next time I used it, same thing, whether its the next morning or next weekend.

Some say I have a sticking inlet needle in one of the carbs. Maybe a anti-siphon valve ? Any help ?

 

[oldman570]

Re: Hard start and half throttle

I have a 87 merc 70 HP and I've found out that it is doing as yours. They seem to be cold blooded when equipped with the Commander control wher you have to push the key in inorder to choke it. If I push the botton on the control pivot and move the lever about half way forward I don't have to choke it as often till it warms up. Might want to give it a try.
Oldman570:facepalm:

 

[BonairII]

Re: Hard start and half throttle

It's better on your motor if you let it warm it up for a few minutes(even when it's running well) before mashing the throttle down.