Think fuel problem

[bjg024]

89 force 50. Ran out of fuel and switched tanks. Boat was still running when I switched tanks. Went to take off and it started to stall out. My primer ball got really hard I could not get it to turn over. I have gas to the carb good spark. Tried cranking it over in the driveway and it backed fired on me. Any suggestions on where to start?

 

[gm280]

Is it possible the second tank had bad gas in it? Sure sounds that way. Smell the gas and see if it smells like gas or something else. Could also picked up some trash in the second tank. :noidea:

 

[bjg024]

Don't think it's bad gas I just filled the tank up

 

[Nordin]

Does it back fire when you crank it? Or does not fire when cranking?

If it back fires it sounds like the flywheel key is shared. Bad fuel does not give back fires.
Back fires is spak (ignition) at wrong time.
If no fire at all check for spark for both plugs. You can have spark at both plugs with a shared flywheel key, but no fire at all because the spak is total out of TDC.

 

[jerryjerry05]

If the flywheel key isn't sheared?
​Then check the fuel.
Do a compression test.
Check for spark.

The backfire could be excess fuel built up.

Sometimes when you pump the ball and it gets hard and the motors hot.
It can cause the float to lock and no fuel gets through.

Try tilting the motor as you try to start.

Went out fishing and the motor wouldn't start for NOTHING!!!
I tried this and that and still nothing.
I got frustrated and decided to run on 1 motor(have twin 85's)
Well during that time I moved from spot to spot.
I got the keys mixed up and grabbed the wrong one.
It started while in the up position.
For a while after that it was the only way it would start?
Finally it stopped needing the tilt.

 

[bjg024]

It only back fires when I hold the choke on to try to start it. I think something is blocking the fuel from getting to the plugs

 

[bjg024]

When I hold the choke down it fires right up. As soon as I let of on the choke it dies

 

[Jiggz]

Sounds like a clog carb jet. Or it could only be firing on one cylinder. To check, keep it running by holding the choke and then pull each plug wire one at a time. The wire that doesn't affect the rpm of the engine is not firing.

 

[jerryjerry05]

You check the flywheel key?
Do a spark and compression test.
Clean the carb.