Johnson 90 hp v4 - sign of when to rebuild my carburetor

[ib18]

I have not used my Johnson 90 hp every week as faithfully as last year. Last year, I never spray the starting fluid except in the beginning of the season. This year I had to spray the starting fluid to cold start. As long as I used it in the same week, then I don't need to spray. I have been mixing seafoam with my gas/oil in my external tank to decarb. A lot of smoke coming out whenever i use my boat and Johnson 90.

So, 2 questions:
1. is it time to rebuild my carburetor?
2. should I be running my motor in the driveway more than 10 minutes to decarb? less than 10 min? what is the best and appropriate running time to decarb. Keep in mind I run the seaform when I launched my boat this year all season.

 

[ondarvr]

What year is the motor? Cleaning the carbs never hurts, but checking the choke or Primer, whichever one it has, would be the first thing to do.

 

[Fed]

I agree with ondarvr, being a 1982 model you have a primer solenoid so here's what you need to do.

1) You have to use the primer solenoid for cold starts.
2) The primer solenoid has to energize (you will hear a click)
3) The solenoid has to pass fuel through it when energized and the engine is cranking or someone is squeezing the primer bulb.
(You can check this by carefully removing the primer solenoid output hoses and watching for fuel)
4) The passage from the solenoid to inside the engine intake must be clear.
(I suspect you could check this by simply blowing through the hoses you previously removed)

A little warning, I believe the primer solenoid fuel barbs can be a bit fragile with age so treat them gently.

BTW, welcome back.

 

[ib18]

wow, thanks for the quick response. I haven't been boating much this summer. Alaska trip was really really nice, cannt wait to go back there to get more salmons.

 

[ib18]

Oh, one more question - is starting fluid bad for my Johnson 90hp motor? somebody made a comment on my youtube channel stating DONT use starting fluid because it is bad for my motor? Why is that?

 

[ondarvr]

Most starting fluid doesn't contain any oil, so while just a small squirt to start it isn't a huge issue, if you continue spray it to keep it running there will be no oil. Also it ignites easily (which is why it works so well) and the motor will frequently detonate (ping) in protest, which can cause problems.

You can buy it with oil added, so that part of it being a no no can be eliminated.

 

[emdsapmgr]

As ondarvr indicates, there is a difference between a carb starting issue (fuel primer system) and a carb running issue. A poor starting issue could easily be attributed to the fuel primer. A poor-running engine could be attributed to internally dirty carbs. Carbs probably need rebuilding if they exhibit a "lean sneeze" at idle or won't run well through the rpm range. You did not say anything about the engine not running well, once it's started and warmed up. .

 

[ib18]

As ondarvr indicates, there is a difference between a carb starting issue (fuel primer system) and a carb running issue. A poor starting issue could easily be attributed to the fuel primer. A poor-running engine could be attributed to internally dirty carbs. Carbs probably need rebuilding if they exhibit a "lean sneeze" at idle or won't run well through the rpm range. You did not say anything about the engine not running well, once it's started and warmed up. .

Thank YOU all. This was very well explained.


The engine runs flawlessly, idling very well. In DC many areas on the Potomac river are no wake zone. So, my Johnson 90 hp idle through a couple miles of no wake zone without any hicups, so I guess my carbs are in good condition. I also took it for a spin in the Chesapeake Bay at sandy Point state park today. I started the motor without spraying starting fluid, because I forgot to bring it with me - LOL. The only thing I did differently is I primed it a couple times before I turned my key to make sure I hear the primer clicking sound. I started it up today on third crank, so I am very very pleased.

 

[ib18]

Most starting fluid doesn't contain any oil, so while just a small squirt to start it isn't a huge issue, if you continue spray it to keep it running there will be no oil. Also it ignites easily (which is why it works so well) and the motor will frequently detonate (ping) in protest, which can cause problems.

You can buy it with oil added, so that part of it being a no no can be eliminated.

Thanks a lot for your explanation.

 

[ib18]

I agree with ondarvr, being a 1982 model you have a primer solenoid so here's what you need to do.

1) You have to use the primer solenoid for cold starts.
2) The primer solenoid has to energize (you will hear a click)
3) The solenoid has to pass fuel through it when energized and the engine is cranking or someone is squeezing the primer bulb.
(You can check this by carefully removing the primer solenoid output hoses and watching for fuel)
4) The passage from the solenoid to inside the engine intake must be clear.
(I suspect you could check this by simply blowing through the hoses you previously removed)

A little warning, I believe the primer solenoid fuel barbs can be a bit fragile with age so treat them gently.

BTW, welcome back.

Thanks!
I totally forgot about the primer solenoid, so I didn't use it as I did last year. I primed it a few times before I turned my key today at Sandy Point state park and engine performed flawlessly. Got it to start on my third crank without spraying the starting fluid.

 

[ondarvr]

You don't need to push it in several times, it's not a pump, it just opens a valve, as long as you keep it pushed in fuel will flow. Push and hold it in and turn the key, once started you may need to push it in a couple times to keep it running. Sometimes pushing it in and holding it in for a few seconds before turning the key helps it start faster.

 

[ib18]

You don't need to push it in several times, it's not a pump, it just opens a valve, as long as you keep it pushed in fuel will flow. Push and hold it in and turn the key, once started you may need to push it in a couple times to keep it running. Sometimes pushing it in and holding it in for a few seconds before turning the key helps it start faster.

Thanks for the tips. That explains why I was not able to start my motor in the first crank consistently. Sometimes I remember to push in and hold it a little longer and then turn the key. Sometimes I just push in hold and turn the key right away. In general it starts no more than 5 or 6 cranks cold start so far.

 

[ib18]

I was able to cold start my Johnson 90 hp with only 3 cranks at my Lake Anna outing. Thanks for the instant tips and help.You guys rock!

 

[sutor623]

I was able to cold start my Johnson 90 hp with only 3 cranks at my Lake Anna outing. Thanks for the instant tips and help.You guys rock!

Thats cool man, right there at the state park ay? Anna is my stomping ground!!