OB Fuel line question

Steve Sanford

Steve Sanford

Well-known member
All~

I am lengthening a fuel line so the tank can sit up under the foredeck.

Question: Does it matter whether the bulb is located closer to the tank or closer to the outboard itself?

Thanks!

SJS
 
Steve,


Yes it matters. Locate the bulb closer to the tank. Squeezing the bulb pushes the fuel. The bulb returning to full diameter sucks the fuel. One will create more pressure when squeezing than the bulb will be sucking. Therefore the longest run should be where you create the greatest pressure.
Factory lines have the bulb closer to the motor purely for convenience. (don't put the bulb so close to the tank that it will be hard top get to)
 
I put my tank in the bow also. Had the bulb near the tank and was very inconvient for me. Moved it up next to the motor. Once you get the air out of the line first time, never had a problem. I always give it a pump or two before dropping in the water. On rough launches I start it on the trailer [I know that's a no no].
 
Once you get the air out of the line first time, never had a problem.
Click to expand...

That's why it is called a primer bulb. It only primes the fuel line so the fuel pump can pump the fuel. The bulb location in the fuel line will not affect the operation, good or bad, of the fuel pump.
 
All of mine are back by the motor, after the water fuel separators. This way you I me not only the motor by the separator.
Click to expand...

Not to say that you are wrong or it won't work, but the directions on my filter said to put the bulb between tank and filter. I have also had my bulb at the motor and that worked before the filter . This is on a 15 foot run of 3/8 (or is is 5/16?).
 
I like it close to the engine.
I pump the bulb, pull the choke, set the throttle, pull the rope. All without going to the front of the boat for the tank.
 
Steve I have an 18 foot boat that has the gas tank under the front deck. I run the hose along the inside bottom of the boat inside PVC pipe . I think it is 3/4 pipe . I put a little outboard oil on the end and feed it through. When i get enough through I attach the bulb closest to motor. this protects the hose from damage.
 
Even though you are correct, I've run them both ways & never had a problem with either.

It's more convenient for me due to enclosed tank & filter.

This way I have no hatches to open.

Disadvantage is due to salt & sun I replace the bulbs every couple of years.


All of mine are back by the motor, after the water fuel separators. This way you I me not only the motor by the separator.
Click to expand...

Not to say that you are wrong or it won't work, but the directions on my filter said to put the bulb between tank and filter. I have also had my bulb at the motor and that worked before the filter . This is on a 15 foot run of 3/8 (or is is 5/16?).
Click to expand...
 
Mine is setup like Capt Jeff and Bob Welsh. I have a 15' boat. The tank is in the bow. I ran a fuel hose from the bow to the stern inside of a 3/4" pvc conduit. At the transom and below the rear deck, the fuel line runs into a water/fuel separator. From the filter, the fuel hose runs to a bulb above the rear deck and then to the engine. This way my son can open the vent on the tank in the bow, if necessary, I can squeeze the bulb and then start the engine. Although, since the initial priming of the bulb, this has not been necessary. The bulb actually begins to collapse. I don't think this is good but it hasn't choked out the engine yet. The bulb did not do this previously to me moving the fuel tank to the bow.

Chad A
 
The bulb is usually last in line, just before the motor. Every factory rigged outboard I've ever owned was/is set up that way. On my phowler the fuel tank is over 20' (of 5/16" ID hose) away. Although it doesn't have to be done very often, since the motor is plumbed into the system without a quick disconnect, the fuel primes fine with the primer bulb at the transom.
 
mine is feeding the Racor filter, filter feeds the motor. I've done all my boats that way with never a problem.
 
You must log in or register to reply here.
Back
Top