Primer bulb problem

Facts: 50 HP Suzuki 4-stroke outboard; 18 gal fuel tank in the bow of a 16 ft Glasspar; Approx 18 feet of 5/16th fuel line.

The primer bulb goes flat after a few minutes of running the engine. I took the gas cap off to ensure air is getting into the tank, but the bulb still goes flat. The fuel pump suction must be more than the fuel line can deliver, or the smaller bulb can deliver, or both. I figure it's like trying to suck coke thru a very long soda straw with a mushy embolism (bulb) in the middle. The bulb is going to collapse.

Question 1: Will a 3/8th line and bulb make a difference?

Question 2: Do they make a larger, more robust bulb than the low-end Moeller that they carry at West Marine?

Question 3: Is there an alternate priming mechanism (i.e., something other than a squishy bulb)?

Re: Primer bulb problem

more history please, did it ever run ok for you. did this just start? usually its an air leak or bad pump

Re: Primer bulb problem

New motor (less than one hour). New (used tank, but new to the boat), long-cruise tank in the bow. Before this I was using a luggable, 6-gal tank sitting near the transom. I had the same thing happen with the same brand of 5/16 bulb, which I replaced after proving to myself it wasn't the tank by simply dunking the fuel line directly into the uncapped tank with no bulb in the path. It ran just fine in this configuration (but I only ran this way while on the trailer, since it's not a safe practice).

The bow is light, so I am hoping the 18 gal tank will balance out the boat a bit.

Re: Primer bulb problem

so let me get this striaght if you prime engine with bulb and the remove line from in front of bulb and put it into tank it runs fine?. then your right its the bulb, is it installed right way?(sorry) had to ask. but i run an 75 hp suzuki on a 5/16 line/hose no problem. I also have run fuel delivery test i get about a cup of fuel out of pump at idle in about 10 seconds. there isn't any fuel pump test i can find in my factory manuals, so this is the best i can figure. i did have a carb problem so i tested every thing until i found problem, dirty carbs

Re: Primer bulb problem

Look in the frequently ask questions part of the forum for testing fuel system.
You have a restriction some where, maybe it is in one of the check valves in bulb

Re: Primer bulb problem

Check the check ball on the pick up at the tank. They hang up and cause greif

Re: Primer bulb problem

Ok, you have a vacuum issue. Of course it will run on the trailer with no problem.....replace the ENTIRE line with 3/8 and the bulb also. Were you running the boat at WOT for 15 minutes in gear on trailer? If not then it don't count at all. If you were then I'm stumped.