2016 20hp 4stroke starving for fuel?

[howie597]

hi, I have a 2016 20hp 4stroke that seems to starve for fuel after running wide open after a few minutes, if I quickly pump the bulb it will keep going, if not it stalls. any ideas, my local shop is closed for the season. thanks

[pstephens46]

Prob going to need an exact model number.

[howie597]

it's a model F20SMHA, Serial #1059121

[fairdeal]

stating the obvious: if pumping the bulb cures the symptom,

then

- the fuel pump is not working properly

- or there is an air leak between the pump and the bulb

- or there is a restriction between the tank and pump which the additional "help" of the primer overcomes

odd little fuel pump btw.

what does the extra "cylinder" with the brass hose barbs do?

[99yam40]

I do not know but water flow would be my guess to cool fuel maybe

[TownsendsFJR1300]

Looks like it plumbs into a water jacket "outer exhaust plate":

Hose routing:
http://www.boats.net/parts/search/Ya...UEL/parts.html

Outer exhaust plate (part #8) where hoses go to:
2006 and Later F20SMHA_01 Yamaha Outboard CYLINDER CRANKCASE 1 Diagram and Parts


You have to look at both parts fisches to follow the hose barb/hoses which lead down to the mentioned plate that has an anode in it...



.

[boscoe99]

Fuel cooler. Fuel/water heat exchanger.

[99yam40]

Do I win a prize for guessing correctly?

[TownsendsFJR1300]

Do I win a prize for guessing correctly?

Yep, but I do too... I had to do some research!

Thinking about it, not much else those TWO extra barbs would do...

[fairdeal]

Fuel cooler. Fuel/water heat exchanger.

doesn't seem much transfer surface - but must have an effect, or they wouldn't bother with it

and perhaps another possible "failure mode" for the OP :

if the pump housing is not cooled as designed, due to insufficient water flow

could that result in "vapor lock" -

(fuel "boiling" on the suction side of the pump)

[howie597]

thanks

thanks for the input, i'll check for air leaks/blockage before I take it in for warranty, I heard the earlier ones had a vapor lock problem

[cpostis]

thanks for the input, i'll check for air leaks/blockage before I take it in for warranty, I heard the earlier ones had a vapor lock problem

I'd check to be sure you have water flow through that cooler. Regarding size, your motor should draw only about 5.3 oz per minute gasoline near max output.