1976? mercury 850 problems

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huntingnemo05

Recruit
Joined
May 25, 2010
Messages
3
Hi if anyone can help me i would like some advice on my 850

the motor has spark and fuel just wont fire and run if it does fire and run it only stays running for about twenty seconds any ideas out there
 
chum1

chum1

Petty Officer 1st Class
Joined
Apr 15, 2010
Messages
359
Re: 1976? mercury 850 problems

possible air leak in fuel system or faulty diaphram in fuel pump. Could be just burning up the fuel in carburetor bowls then dying.
 
SeaKaye12

SeaKaye12

Lieutenant Junior Grade
Joined
Jul 3, 2005
Messages
1,110
Re: 1976? mercury 850 problems

One quick way to check if its a fuel issue would be to continuing to squeeze the ball once the engine starts and see if that keeps it running.

If so; you know it's fuel starvation.

Then; you'd want to check and double check everything in the path of fuel...from the pick-up in the tank to the hoses that connect to the carbs.

Look for obstructions and/or air leaks.

You have the vent in the tank open; right?

Good luck, Chuck
 
abarron

abarron

Petty Officer 3rd Class
Joined
May 9, 2010
Messages
80
Re: 1976? mercury 850 problems

How ya doing?I myself have a 850 74 model i would take it out on the lake and it would bog down and quit,my son was with me and noticed the bulb squeezed shut when it would run and start to bog,he pumped the bulb and it would pick up.Anyway it was my inboard tank trashed.I hooked it up to a 5gal tank and run SEAFOAM in it.Now it runs great! I'll ether pull the tank and clean it or install a new one.Hope this helps!;)
 
H

huntingnemo05

Recruit
Joined
May 25, 2010
Messages
3
Re: 1976? mercury 850 problems

hey guys
thanks for all the help you guys are giving me going to take the boat to the lake this weekend and hope for the best
 
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