Air in Fuel Line

[XJMikey]

I have an 81 Chrysler Sea King 7.5hp. I have a problem with air in the fuel line. When I did the carb kit on it I put a clear fuel line on it from the diaphram pump to the carb. When I run it I notice that after a couple minutes there are air bubbles developing in that clear fuel line. All of the fittings, fuel line, and pressure bulb are new. I also replaced the diaphram and gaskets in the pump about 6 months ago. I do not see any leaking fuel or hear any sound of air suction anywhere on the line from the tank to the motor. Eventually the air bubbles turn into a big gap of air filling up half of the fuel line and thus killing the motor due to lack of fuel. If I squeeze the bulb a few times it will clear the air out and will be full of fuel all through the line, then it starts all over again filling with air. I ran it with the cap of the gas can off to make sure it was vented and it still did this.

Any ideas?

Mikey

 

[bustermin]

Re: Air in Fuel Line

does the primer bulb get firm? it almost sounds like the check valve isnt working. also this is kind of a long shot but do you know what rpm it is at idle, if im not mistaken your pump works off of vacume, so if your not idleing high enough it may not create enough vacume. did you make sure there was no blockages to the orifice behind the diaphram? more than likley the problem will be with somthing you touched, double check your carb adjustments.

 

[XJMikey]

Re: Air in Fuel Line

The bulb doesnt seem to be staying really hard, but you can tell it has pressure in it. Is the check valve you are talking about in the bulb? Also, it still gets air in the line at both idle and high speed.

Would a blockage cause it to have air in the line?

The motor runs perfect when it has fuel. It purrs along at idle and sounds great at WOT. pretty impressive for the age of the motor actually. Just this darn air problem

 

[Phoenixfirewalker]

Re: Air in Fuel Line

id say try a new bulb and get rid of the clear tubbing once the problem is solved
also check the fittings and ties

 

[bustermin]

Re: Air in Fuel Line

yes the check valve is part of the bulb. i know they sell new primer bulb lines at Walmart, but if you can avoid it and i would get a quality one from a marine store as i have heard of the ones at Walmart are not the most reliable.

 

[XJMikey]

Re: Air in Fuel Line

Got a new bulb from the local marine dealer and put it on. Same problem, but I did notice something with the fitting/connector that connects the fuel line to the motor. Before I hooked up the gas line I squeezed the bulb and air came out the fitting. I pushed on the inside of it with a screwdriver to re-seat the innerds of the fittig and squeezed the bulb again. No air came out that time. Pretty sure that fitting may be causing my headache with letting air in by possibly not seating correctly. Sits good at first with no air bubbles but I am thinking the vibration of the motor may jiggle it to the spot where air may get by. Ordered a new fitting and will try that out. Trial and error sure sucks