1979 johnson 70 horse

smcgillis

Recruit
Joined
Jul 9, 2006
Messages
2
hi i have a 1979 70 horse johnson. it has ran fine up to today. start it up runs ok try to go and it just loads up i think. wide open the motor is blowing lots of exhaust out and i just barely move. the prop is fine. i replaced all the fuel lines the fuel the spark plugs and the vacuam line coming from the motor to the fuel pump. it is just the same no difference. what might be the chance it is the fuel pump.
 

jim_in_day

Petty Officer 2nd Class
Joined
Aug 29, 2005
Messages
175
Re: 1979 johnson 70 horse

when you say wide open, do you mean that the throttle is all the way forward and you have no rpm's or do you have wide open throttle rpms and the boat is not moving? If the motor is truly revving up and not moving, you have a spun prop. If you are getting low rpms, you have a different problem and we need to check to make sure you are getting spark to all 3 cyls
 

tashasdaddy

Honorary Moderator Emeritus
Joined
Nov 11, 2005
Messages
51,019
Re: 1979 johnson 70 horse

sprak to all 3 cylinders, and a compression check. i agrre with Jim , please clarify statement. very confusing.
 

smcgillis

Recruit
Joined
Jul 9, 2006
Messages
2
Re: 1979 johnson 70 horse

tashasdaddy said:
sprak to all 3 cylinders, and a compression check. i agrre with Jim , please clarify statement. very confusing.

well its bouging out is what my dad says. you can take off normal at slow speeds but when you go to take off to go fast it just bougs right out like it wants to die but it stays running.
 

rickdb1boat

Supreme Mariner
Joined
Jan 23, 2002
Messages
11,195
Re: 1979 johnson 70 horse

In that case, try pumping the fuel primer bulb and see if that helps. Also, try hitting the choke and see if she goes. If it goes while pumping the bulb, it's either the fuel pump or an air leak in the lines...
 

jtexas

Fleet Admiral
Joined
Oct 13, 2003
Messages
8,646
Re: 1979 johnson 70 horse

Idles fine, sounds good with no load, but bogs down when you try to accelerate? Classic symptom of fouled carbs. Rebuild with new carb kits.
 
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