fuel pump test

[allaboard]

how can I provide a fuel pump test on yamaha 40 2 stroke?

Do I need a gauge?

[99yam40]

yes a fuel pressure and vacuum gauge would be needed , but you can just replace if it is leaking or has been many years since replaced.

What problems are you having?

[allaboard]

motor just run properly when squeezing the primer ball.

Where should I connect the gauge? in the fuel line before the fuel pump or between fuel pump and carburettor?

What are the reference values for a good working pump?

[rodbolt17]

need 4PSI minimum output with less than 4"Hg at the intake.
myself as a pain as it is to cut in a guage I would simply replace the pump.

by pumping the fuel primer and it works either the pump is bad OR there is an air leak between the primer and the pump intake.

[allaboard]

thanks a lot

[rodbolt17]

don't mean to be smart but think about it.
your comment"motor just run properly when squeezing the primer ball".
that just told me fuel was avalible at the primer yet not in the fuel bowl.

now lets get it to the shop.
I will also assume its oil injected.
now I am going to remove the oil tank,Tee in a fitting,take it to the water,test run it, if pressure fails now I remove the oil tank again,move the Tee to the suction side and retest at the failure RPM and load.
now its back to the shop to remove all this test stuff.
this is done at 90 dollars an hour and you have already told me the problem.
so right now I have been dinking on your engine for about 1.5 hours and NOW I tell you, you need a fuel pump.
takes 15 min to change it and the pump is about 50 bucks.

that pump does not live forever and should be changed about every 3 years of use.

so now I have 1.75 hours in your rig at 90 bucks an hour and a 50 dollar pump.

as a technician I just made a decent gig.

as a professional I just ripped you off.

in that same time I could have stripped the carbs,cleaned them cleaned the engine filter and replaced the pump.

[robert graham]

I replaced my 5 year old pump(but still working fine) with a new one and kept the old one in my boat tool box for a spare down the river somewhere....you gotta figure at 4 or 5 thousand RPM's how many times that little plastic diaphragm is gonna flex before it fails....I wish everything in my life worked as well, and was cheap and easy to replace as that little fuel pump...just another reason to hang onto these old simple, 2 stroke outboards!.....good luck!..