Please help with 75 hp Johnson

[cenrique]

I have been having problems with this outboard since day 1, seems like this engine has not been used in more than a decade. The symptoms it is having is that it looses power and seems to be running in only 1 cilynder on full speed , but this does not happen all the time, for instance i took it to the river last month and it worked fine and yesterday i took it to the ocean and it started giving me problems. Also when i start the engine with the warm up lever up all the way it takes a minute for the engine to accelerate. I have changed water pump, compression is 120 on each cilynder, carbs have been rebuilt supposely by this guy that knows some about outboard, also i have changed coils, control cables, spark plugs and wires. I am so frustrated, please any ideas?

Thanks

cenrique

 

[bannerd]

Re: Please help with 75 hp Johnson

Are both plugs firing properly? You could test this pretty easily.

Also how old is the gas?

 

[seasprite]

Re: Please help with 75 hp Johnson

check your fuel tank for restrictions and see if it is vented properly if there is dirt or debrie in the tank if there is you might be redoing the carbs check the screen at the fuel pump if don't have an inline fule filter.

 

[cenrique]

Re: Please help with 75 hp Johnson

Are both plugs firing properly? You could test this pretty easily.

Also how old is the gas?

Gas is new but i have not checked if both plugs are firing, how do i test this?

Thanks

 

[cenrique]

Re: Please help with 75 hp Johnson

check your fuel tank for restrictions and see if it is vented properly if there is dirt or debrie in the tank if there is you might be redoing the carbs check the screen at the fuel pump if don't have an inline fule filter.

I have installed inline fule filter this year thinking that that might fix the problem but nothing. One think i checked is the fuel tank vent was closed do you think that could cause that kind of problem?

 

[seasprite]

Re: Please help with 75 hp Johnson

Its possible because as fuel pump takes fuel out of the tank with no vent it puts the tank under a vacuum then your fuel pump has to try to over come the draw of vacuum eventually your fuel pump won't be able to supply enough fuel for proper operation and the motor will starve for gas and run lean because you can't get the fuel you need to the cylinders. Hope this was your problem be a simple fix and cheap Let us know if this works.

 

[tashasdaddy]

Re: Please help with 75 hp Johnson

what 75 it makes a big difference?

 

[cenrique]

Re: Please help with 75 hp Johnson

Its possible because as fuel pump takes fuel out of the tank with no vent it puts the tank under a vacuum then your fuel pump has to try to over come the draw of vacuum eventually your fuel pump won't be able to supply enough fuel for proper operation and the motor will starve for gas and run lean because you can't get the fuel you need to the cylinders. Hope this was your problem be a simple fix and cheap Let us know if this works.

I started the engine yesterday and it was running fine, but i have not tried it in the water yet, hopefully this was the problem, i will let you know guys.
Thanks again for the help.

 

[cenrique]

Re: Please help with 75 hp Johnson

what 75 it makes a big difference?

It is a seahorse 75 hp 3 cilynders.