76 merc 850

[dchris]

I'm fresh back from the lake with my 76 merc 850, which just got a new fuel pump, re-built carbs and water pump. Things started out well, it was easy to start and I could get the boat up to about 30mph. After about 30 min of running her hard at high trottle, it would just lose power and slow down to idle speed and stall. It would still restart easy and you could get the rmp up for a short bit before it would stall again. I'm not sure how to trouble shoot this. Any ideas?

 

[Chris1956]

Re: 76 merc 850

Try to pump the primer bulb to keep it runing. If the bulb goes flat, you have a restriction in the fuel line, between the tank and the primer bulb. A lot fo times this is caused by the antisiphon valve clogging.

If the bulb doesn't get flat, and the motor runs well, the fuel pump is likely bad.

If the primer stays hard, and the motr dies, troubleshoot the ignition.