1979 johnson 70hp wont throttle up

[hatchcraft]

I have recently purchased a 14 foot speed boat with a 70 hp johnson.Motor has not run since last year.With little work it started.Took it to the lake and would not throttle up very well all the time but every once in a while with the throttle wide open it would take off and fly accross the lake but then drop right off again??Any ideas????..

 

[ezeke]

Re: 1979 johnson 70hp wont throttle up

If ANY of the gas you are using is older than 60 days, get rid of it and clean the tank out.<br /><br />You probably have floats that are sticking, due to gummed up float bowls. You may get improvement by using carb cleaner in the bowls after draining them, but a carb rebuild may be needed.

 

[hatchcraft]

Re: 1979 johnson 70hp wont throttle up

i did clean the carbs and never started the engine until the new gas was added.Two of the carbs were not getting any fuel at all due to stuck float needles.Fixed that but that was before i went to the lake.I could not find any adjustments on the carbs,should there be??and if so could this help???..

 

[hatchcraft]

Re: 1979 johnson 70hp wont throttle up

Last night i took the three carbs completely appart and soaked them in hot water and soap.I put them together this morning and found a small piece of rubber hose(head of stick pin size)between the float needle and it's seat.Tested motor today at the lake for about three hours and it has all kinds of top end but it bogs comming off of idle.I have to back off the throttle until it starts torev up and then i can open it and it stays open.Any ideas on what this is????

 

[hatchcraft]

Re: 1979 johnson 70hp wont throttle up

I dont want to be a bother but i was woundering if any one had an answer to the above problem..

 

[voodoo]

Re: 1979 johnson 70hp wont throttle up

hot water and soap will not clean dirty carbs....you probably have crap in the low speed circuits.

 

[captain spike]

Re: 1979 johnson 70hp wont throttle up

check all fuel lines,fittings for any leaks also get a good carb cleaner

 

[Bass Runner]

Re: 1979 johnson 70hp wont throttle up

Clean the carbs with barrimans b-12, also the fuel pump may be going out.

 

[hatchcraft]

Re: 1979 johnson 70hp wont throttle up

The cleaner you speak of,is it put into the gas or do i need to take those carbs off again?.Another thing ,how much fuel should the pump push out?.I started the engine with the fuel line off to make sure it was pumping it was pulsing out fuel probably two inches or so.Does this sound normal???

 

[hatchcraft]

Re: 1979 johnson 70hp wont throttle up

I have a bottle of carburator cleaner for a vehicle.Is this ok to put into the tank??

 

[hatchcraft]

Re: 1979 johnson 70hp wont throttle up

I should have mentioned that this 70hp johnson was on a 14 foot fiberglass Crestliner so it should'nt be bogging because of what it is pushing..

 

[rglen]

Re: 1979 johnson 70hp wont throttle up

Originally posted by polly:<br /> I have recently purchased a 14 foot speed boat with a 70 hp johnson.Motor has not run since last year.With little work it started.Took it to the lake and would not throttle up very well all the time but every once in a while with the throttle wide open it would take off and fly accross the lake but then drop right off again??Any ideas????..

 

[rglen]

Re: 1979 johnson 70hp wont throttle up

I have had the same problem on a 77 70hp. try taking the cover off and during thorttle up spray the carb cleaner in the carb. Chances are it will power up the way it is supposed to. If that works you may have a problem with your low speed jets.<br />Good luck.