Air in fuel line (is this normal)

[kevinclark93]

I have a 96 150hp. I recently drained the tank and carbs due to water in the gas. I have now notice an air bubble in the clear T where the fuel line and oil lines meet. Is this normal to have an air bubble in the line and if not what is the best way to get rid of it. The motor runs fine, it was very hard to start yesterday, normally cranks right up, but i may have flooded it.

This is a great forum and has already saved me hundreds of dollars thanks for the help.

 

[capslock118]

Re: Air in fuel line (is this normal)

No, that's not normal.

Usually has something to do with a loose line somewhere and air is getting sucked in.

I'll go into my '90 135hp service manual later this evening to write out what mercury would have you do if no one else gives you the steps by then.

 

[kevinclark93]

Re: Air in fuel line (is this normal)

That would be a huge help. I am almost certain the air is there because I probably did something wrong after i drained the tank and refilled it. After draining I have air in everything.

 

[j_martin]

Re: Air in fuel line (is this normal)

An air bubble in the oil line is no big deal. When you're tinkering around at idle, there's not enough oil flow to push it out. One high speed pass will push it on out through the fuel pump. It just got there when you were cleaning out the fuel lines.

If air is coming in from the bayonet, you have a small leak somewhere between there and the fuel tank sucking in air. That can cost you a piston if it's not dealt with.

Hope it helps
John

 

[capslock118]

Re: Air in fuel line (is this normal)

In my v6 135hp service manual:

Problem: Air Bubbles in Fuel Line
Possible Causes:
low fuel
loose fuel line
fuel pump fitting loose
a hole or cut in fuel line
fuel pump anchor screw(s) loose
fuel pump filter cover anchor screw loose
fuel pump filter gasket worn out
fuel pump gasket(s) worn out

corrective actions relative to possible causes outlined:
fill tank
check and tighten connections
tighten fitting
check condition of all fuel lines and replace any found to be bad
tighten all screws evenly and securely
tighten screw securely
replace gasket
rebuild fuel pump