RD16 Doesn’t run when tank is below 1/3

[hmai]

I have a 1955 Johnson 25hp. I believe it is a rd16s.
Motor runs like a swiss watch and its my weekly user. It is however finiky about which 2 line pressure tank i use. (I have 1/2 a dozen). I am sure it was never converted to a fuel pump and i struggle to believe all tanks are bad. When the tank gets down between 1/3 to 1/2 a tank it will.not run. Does this sound like a reed valve issue. I keep scratching my.head, because if either the tank or reed valves were bad i doubt it would run well at all.

---

Attachments:

[dougs-outboards]

"Motor runs like a swiss watch and its my weekly user. It is however finiky about which 2 line pressure tank i use. (I have 1/2 a dozen)".

Are you saying some of your tanks work and others do not?

If so, use the tank that works.

If not, my first obvious thought is a faulty fuel pick up tube inside the tank. Maybe has a pin hole in it 1/3 to 1/2 way up the tube? Visual inspection is called for. Pop the top on that and check out the pick up tube. You can slap some "schlock" (I use 847) on the tank top gasket and generously on the screws to seal it back up. After that, dunno. Maybe some other geniuses will chime in…

[chris-p]

Do the finicky tanks work fine on other motors?

[chinewalker]

Something to check… I recently had an issue with a later single line tank where the pickup tube was split for about 4 inches along the side. The tank worked fine until the level dropped below about 2/3 full and it would start sucking air.

[frankr]

Is the motor pressuring the tank? It should build to around 4-5 psi. Is not, there may be a problem with the rubber check valves on the reed plate. I’ve seen some turned to goo, Possibly non ethanol tolerant? I dunno.

[Author]

Posts