93’ 20 hp Evinrude loses prime at low idle

[PickerelSlayer]

Motor is a 1993 20hp Evinrude.
the motor runs great at WOT and mid throttle, but after trolling with it for about 15-30 mins the motor dies out and the primer bulb is soft

Sometimes i can catch it and prime the primer before it dies out .

Im assuming I have a air leak, question is how can I narrow down where the leak is?

-Bought gas tank and hose 2 years ago(not gonna rule it out yet)
- checked for obvious splits of holes in gas line( engine side and gas tank side) but couldn’t find anything

 

[Joe Reeves]

You state the primer bub goes soft....... The Fuel Primer Bulb is hard only when you prime the engine... During normal running, the fuel primer bulb is usually just laying on the deck or motor well in a horizontal position. Now, in that position, even when running full throttle, the fuel level will drop to the halfway mark which is normal and the bulb will of course be soft. This is the nature of the beast so to speak and does not affect the running of the engine.

If a air leak existed, by the same token, you would have a fuel leak... and if you didn't notice it, I think you would surely smell it.

Your problem sounds more like the fuel pump diaphragm has perhaps stretched and is simply not able to pump as long at a low rpm as it once did. A rebuild or replace situation I'm thinking.

 

[PickerelSlayer]

Thank you for the quick reply Joe. I will purchase a fuel pump rebuild kit and get back to you with results.