Mercury to Johnson fuel tank.

[carleton]

I changed the fitting to the Mercury tank to run my Johnson motor but I can't get it primed.When I squeeze the ball I can here air pushing from the motor end of hose.It is a old tank that I don't know if it is flawed.What can I do to correct this problem?
carleton

 

[Will Bark]

Re: Mercury to Johnson fuel tank.

The only thing I can think of is are the arrows on the primer ball pointed to the motor?

 

[carleton]

Re: Mercury to Johnson fuel tank.

Yes the arrows are right.

 

[Daviet]

Re: Mercury to Johnson fuel tank.

Sometimes one of the check valves in the primer bulb will stick, try holding the primer bulb in a vertical position, fuel flow towards the sky, and try pumping the primer bulb. Make sure the hose is attached to the engine.

 

[carleton]

Re: Mercury to Johnson fuel tank.

That did the job.

 

[Daviet]

Re: Mercury to Johnson fuel tank.

Glad you got it fixed.

 

[carleton]

Re: Mercury to Johnson fuel tank.

Now I am ready to get it started.Is there a place I should set the two buttons going to the carb?

 

[Daviet]

Re: Mercury to Johnson fuel tank.

You are going to have to tell us what engine we are working on, model number?

 

[carleton]

Re: Mercury to Johnson fuel tank.

It is a 4W71D

 

[Daviet]

Re: Mercury to Johnson fuel tank.

OK, the top one is the low speed needle valve, static setting is 1 1/4 turn out from lightly seated. The bottom one is the high speed needle valve and the static setting is 3/4 turn out from lightly seated. You will have to fine tune both of them with the engine on the boat in the water. Adjust the slow speed needle to get the best idle while under way and then open it another 1/8 turn. With the engine at wide open throttle, adjust for best rpm, and then open it another 1/8 turn. These adjustments have to be made with the boat in the water and not tied to the dock.

 

[carleton]

Re: Mercury to Johnson fuel tank.

Well now I have to asked what the compression should be on this motor?It doesn't seem to have much.

 

[Daviet]

Re: Mercury to Johnson fuel tank.

They don't list the specs for compression, but I would think somewhere around 65-75 psi. More important it should be within 10% of each other. Has the engine been sitting for awhile, might have some stuck rings. See if you can get it started and try a decarb on it and see if it helps.

 

[carleton]

Re: Mercury to Johnson fuel tank.

I don't know the history on the motor but I would guess it has been sitting.Is there a product that can be sprayed in the spark plug holes to free the rings?

 

[Daviet]

Re: Mercury to Johnson fuel tank.

You can do a decarb using sea-foam, run a search, several posts on it. I don't know if spraying anything through the plug hole will do a complete decarb, guess you could try it.

 

[carleton]

Re: Mercury to Johnson fuel tank.

.Now it it will rev up full throttle and run wide open for 30 seconds then idle down on its own and stop running.Any ideas what needs to be done?It only runs when the choke is closed almost all the way.
carleton