External GAs Tank on Outboard for Dinghy

[mmcguire2002]

I added an external gas tank on my 4hp, 4 stroke outboard yesterday. I took it around the harbor to test it out. It would occasionally die on me. Once I pumped the primer bulb and then started it again it would run for another 10 minutes, then require the same procedure.

Is this normal activity for an external tank? Do you have to prime the bulb occasionally while in use?

 

[The Bill Collector]

Is vent screw on the gas cap loosened....?

 

[mmcguire2002]

Is vent screw on the gas cap loosened....?

Yes, the vent screw is open during use.

 

[The Bill Collector]

Sorry, but had to ask.... The other simple item with the fuel bulb not keeping full sounds like air in the line.... possibly pin hole, loose hose clamp, bad connection. If you have a friend with same fuel supply line borrow it and run dinghy around with it...? The other thought I just had... Does your motor have an internal tank and is that vent screw closed ? I do not have this on my outboard so I'm not familiar with whether it should be open or closed when using an external tank. I now have exceeded my level of expertise and will not comment further... Good Luck !

 

[Lazy Daze]

You shouldn't have to keep pumping. Try opening the vent more, or loosen the cap - just to see if there's something wrong with the vent. Be careful not to let any fuel slosh out - depending on how loose you make the cap.

Also, make sure all the gas connections are tight - engine side and tank side. Sounds like it's running on what's in the fuel line, and then not drawing any more.

 

[Bob M]

I recently purchased a 4-stroke, 4 HP Yamaha. I was surprised to see the coupling for an external fuel tank. I purchased a new gas line for my Merc 3-gallon tank to convert it to the Yamaha connection. It worked just fine.

I was told I could lay my 4-stroke down on the tiller side of the OB or with the prop facing down. I left it on the boat prop-side down and found oil on the floor leaking out of the motor cover. Needless to say, it wasn't a pleasant find.