The International Cessna^® 170 Association

The '48 still needs a fuel pump when a O-300 D is installed, or does that requirement go away?

First guess is yes, the plane would still require a fuel pump.
The '48 needs a fuel pump because of the fuel line routing, no? That wouldnt change with a different motor.

The fuel pump must be used with any engine listed in our STC in a 170 though the instructions do not specifically say that. What the STC says in general is you install a 0300 C,D or E as if you were installing a C-145 using all the same accessories and installation techniques except where the later 0-300 is different. And the differences are principally the 6 bolt flange requiring a different prop and the angle starter on the D and E engines.

We know the reason for the fuel pump was the size and routing of the fuel lines and that is not changed with the 0-300 install and so the need for the pump is just as necessary as if ever was.

Bruce Fenstermacher wrote:The fuel pump must be used with any engine listed in our STC in a 170 though the instructions do not specifically say that. .....

I know what you meant...but that isn't what that says. "Our" STC does not require a pump "for any engine listed in our STC". You explained it later in your response but, just to clarify....

The PUMP is an AIRFRAME (fuel system) requirement. Changing the engine-model (from one C-145/O-300 to another) does not alter that need for a pump in '48/ragwing models.

In other models of 170....if no pump is previously required....then none is req'd with replacement -145/O-300 engines either.

Thanks guys....this helps....the fuel pump on my O-300 A is only a year old and the O-300 D obviously does not currently have one installed, so at least the money I spent on the fuel pump won't go to waste.