fuel pump poor idling

[Arronh]

Hello. I have a 79 15hp, 15r79e. I had to change fuel lines from the fuel pump to the carb. The new fuel line is blue, and I can see through it. With the new line, I noticed that there's air coming from the fuel pump outlet. So, I bought a fuel pump rebuild kit....and there's still air. I gave the fuel pump the blow test like it said it the manual. It passed the blow test. Could air be getting in from the the fuel line that goes into the fuel pump input? Also, could the air in the line be affecting the low idling?

Thanks

 

[Chris1956]

Yes to both questions. Check all the fittings in the fuel line, filter and tank.

 

[Crosbyman]

possibly but much like a vapor separator on modern ETEC or older FICHT

air in the fuel should just rise to the surface inside the carb and just exit out the vent hole leaving just fuel to be drawn by the crankcase vacum via LS and HS jets /needles

if air actually gets sucked in the fuel inlet it is not from the fuel pick-up but more likely a poor joint...along the way to the pump inlet .

bulb to pump inlet is easy enough as fuel would "urinate" out a bad joint .......when pumping the bulb

from tank to bulb leaves few possibilities

 

[Arronh]

Update. Found a zip-tie hose clamp that wasn’t clamping at all. Putting an actual hose clamp on fixed the air issue.

The idling issue turned out to be that the idle adjustment knob, part number 387272, is broken. I was trying to idle it at a level so low that it would never be able to idle. I ended up figuring that out by looking at my other Johnson. Since I spent so much time trying to get it to idle low, it now idles perfectly.

Thank You

 

[Crosbyman]

great knews ..... thanks for your feedback it helps others fixing their problems