I have a Johnson 25 hp outboard that only runs on choke. Any suggestions?

Question

I have a Johnson 25 hp outboard that only runs on choke. Any suggestions?

Answer 1

check the fuel pump diaphragm

Answer 2

if it only runs with the choke closed then you are not getting enough gas.

First: is the squuze ball  hard on the line coming from the gas tank? if not change the ball

Have you checked the screen on the gas line on the motor?

You have a carb motor so there is no adjustment on the high speed jets so it seems that you should maybe pour some carb cleaner in wih the gas. After awhile it may clean out the varnish .

Answer 3

clean the carb

Answer 4

Clean the filter, carb (main jet) and make sure the main jet is properly adjusted.  Back it out until it runs better.  Once it's running well, lean it out until you get peak rpm, then back off 1/8 turn to avoid running hot.

Answer 5

Make sure the air inlet valve on the gas tank isn't clogged.

Answer 6

Yep. it is starving for fuel. The choke is creating a huge vacume differential and is causing fuel to be "pulled" from the fuel source. If the fuel source was free flowing it would run on a regular vacuume.

Check ALL lines and hoses for obstructions. Try ANOTHER tank source. Look at all points for screens, filters, and sharp angles in the fuel lines that could cause a small amount of debris to cause a fuel blockage.

Also, DON'T overlook the fact that MAYBE you put the motor up for storage and did not drain out all of the fuel, thereby cause the fuel to dry out and gum up the small fuel passages in the carb. This will require cleaning out the complete fuel system.