mercury 850 no power and stalls when put into gear

[jvoldarski]

i have a 75 mercury 85hp and i run into an issue usually after i drive it for a while i lose power and then i cant get the boat over 5-10 mph and it then becomes occasionally hard to start and usually stalls when i put it into gear. i can usually get it to drive by putting it into gear and very slowly increasing the throttle but at full throttle it doesnt go anywhere near the max speed i know the motor capable of. i have already replaced the trigger and all the fuel lines in the motor but that does not seemed to have helped at all. also when this was happening last year after it sat for a while it would be able to go full speed again but when i took it out this year it ran full speed for a while then cut out and i tried it the next day and it still wouldnt go full speed.

 

[jvoldarski]

Re: mercury 850 no power and stalls when put into gear

i plan on buying a coil and a fuel pump kit, let me know if you think that would help i dont really have money to throw parts at this.

 

[chum1]

Re: mercury 850 no power and stalls when put into gear

Sounds like an intermittent loss of power, possibly a couple cylinders dropping offline? I would check spark under a load. Best bet is to troubleshoot one system at a time and repair/replace parts as necessary if you want reliability.

 

[bktheking]

Re: mercury 850 no power and stalls when put into gear

Test your stator, I just went through this on a 76 850, red wires ohmed out off the map. Your stator is more than likely heating up and dying out.

blue and blue white disconnected should ohm out to r x1000 5.7-8.0- I got 6.x

red and red white disconnected should ohm out to rx1 56-76, I got 150.

Blue controls spark at idle, red controls spark at high speed, the boat wouldn't come out of idle that I was working on. The new cdi stator I installed ohmed out to 50 on the red wires.

Otherwise could be the switch box or water instrusion into the cylinders but your stator might be the culprit.

 

[jvoldarski]

Re: mercury 850 no power and stalls when put into gear

went to test stator and there are only 2 yellow wires coming off of it so does that mean its only for charging and wouldnt be my problem?

 

[Moody Blue]

Re: mercury 850 no power and stalls when put into gear

You have a battery CD ignition system and the stator is only used to charge the battery. Will not affect operation of the motor as you described

Is it possible that the vent on the fuel tank is not opened up? Running at idle would be OK but the engine would starve for fuel at higher RPM's.

 

[jvoldarski]

Re: mercury 850 no power and stalls when put into gear

The vent was the first thing I checked so I know for sure it's not that plus I can drive sometimes for a good hour before I have a problem

 

[jvoldarski]

Re: mercury 850 no power and stalls when put into gear

The vent was the first thing I checked so I know for sure it's not that plus I can drive sometimes for a good hour before I have a problem

 

[lakerouge]

Re: mercury 850 no power and stalls when put into gear

I'm having exactly the same issue with exactly the same engine. I was wondering if you ever figured it out.

Any info would be great!

Thanks