1983 Johnson 90 Not turning up Fuel Problem?

[Fully_Loaded1]

My 90 is not turning up under load. Out of gear it turns up just fine but when it is under load it sounds like it is bogging and only turns up to maybe 1500-2000 RPM. Sometimes if I hit the choke (it is a primer choke) it will pick up some RPM then fall back off. When I try and start it cold I have to keep hitting the choke when it starts to die until it warms up. Could my fuel pump be bad? Help please. Thanks

 

[Walker]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

More than likely your carbs are gunked up and need a tear down and thorough cleaning.

 

[DJ]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

More than likely your carbs are gunked up and need a tear down and thorough cleaning.

I agree.

Also, revving the engine in nuetral means nothing and it's not good for it.

 

[Fully_Loaded1]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

I have already been int the carbs. They were clean with no tarnish or gunk. I do not rev it up above 3500-4000RPM in neutral and it is for just a second to try and keep it running. I thought maybe the fuel pump.

 

[OBJ]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

Have you checked the spark yet to each hole? Each of the four sparks should jump a 7/16 to 1/2 inch gap with a hot thick lighting like spark.

Back to the fuel, take a spray bottle with some premix in it. With the boat in the water in gear, spray some premix into the carbs and see if the rpms pick up. If they do, likely you still have some problems in fuel delivery.

Did you check the jets when the carbs were apart?

Have you any fuel lines that are hard from years of use? These should be replaced.

Does squeezing the primer ball make any difference? If so, the fuel pump may have gone south.

 

[Silvertip]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

If hitting the choke/primer causes the engine to pick up, the fuel pump is suspect and probably needs rebuilding or replacement.

 

[Fully_Loaded1]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

I intend on replacing the fuel pump. However it does not seem that when I squeeze the fuel bulb there is any change. But the bulb does feel real soft and close to empty. I cleaned all jets and orfices with cleaner. The ful lines seem to be in good shape.

 

[reeldutch]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

whats the compression?

 

[Chinewalker]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

I would double check the carbs. There are lots of orifices and passages in there that MUST be spotless clean. Double check float level. Also, check the recirculation lines. One might be sucking air, creating a lean condition. The key here is the improvement when choked - points to fuel...
- Scott

 

[reeldutch]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

i agree with it thats its a fuel problem probbebly in the carbs.
it might have been running lean for a while and could have done damage on your cylinders.

a compression test will let you know if you only have to clean the carbs.

 

[Fully_Loaded1]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

Compression is between 112-114 on all cylinders. I am going to replace the fuel pump and fuel lines and f that does not work I will tear into the carbs again.

 

[Cricket Too]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

Why waste money on a pump and lines, if you haven't checked for the most likely problem, the carbs. You can't see with your eye when a carb jet is blocked, I'd soak those carbs and put kits in them first. Also check your spark as was suggested. Your gonna start working backwards, just replacing parts is gonna get more expensive than taking it to someone.

 

[Fully_Loaded1]

Re: 1983 Johnson 90 Not turning up Fuel Problem?

I got it fixed, It was the fuel pump. It had a hairline crack in it and was suckin air I reckon. Thanks for the help.