Yamaha Fuel Pump?

[Patman]

Just how important is the spring and seat in a fuel pump?

I inspected my fuel pump for varnish and bad diaphragms, but found nothing wrong except the spring and seat were mising. The Yamaha schematic and my repair manual shows these parts in the assembly.

This motor had run fine for nine month and then developed a rough idle problem in the 1,000-2,000 rpm range while under a load. The motor is a 1989 Yamaha 40hp tiller model.

I have replaced the fuel pump with a new one and also adjusted the idle/air carburetor screws from 2 turns out to 1 1/4 turns out as suggested by another person. I have yet to run the motor under a load.

Thanks!

Patman

[fishkisser]

Originally Posted by Patman

Just how important is the spring and seat in a fuel pump?


Thanks!

Patman

All the parts in a fuel pump are nessesary to make it preform properly ...
2 turns out or 2 1/2 is a starting point for adjustments on your carb ...
all of them usually have a "sweet spot", to find it will take some fine tuning under load ...
Good Luck ...Barney