Boost pump, fuel pump, primer ????

[Dbro172]

All of my flying to speak of has been in Cessnas. In the carb models I recall a primer to assist starting a cold engine. In the FI models of which I mostly fly there is a fuel pump used to start a cold engine (and in emergency procedures). But never a boost pump

I recall flying a piper once (i.e. low wing) that required a boost pump on take off and landing..... What is normal in an RV. For a carb? For an injected? Do I need a primer and a boost pump? Just a primer? If I go FI will I need just a fuel pump?

Trying to decide on an o-320 or an io-320.

[BobTurner]

In a high wing aircraft with a carb, gravity is usually sufficient to get the gas to the carb. No pump needed.
In an aircraft with fuel injection, a pump is usually needed to get the fuel under sufficient pressure to spray thru the injector nozzles.
In a low wing aircraft a pump is needed to pump the gas up to the engine.
If you have a carb a separate primer line is needed. If you have FI the fuel injectors can do double duty as primers.
If you need a pump, standard procedure is to have two pumps in case one fails. Most installations use a mechanical engine driven pump, and a back up electrical pump.
Although there are exceptions, most installations recommend running both pumps anytime you are so low that you might not have time to turn on the back up should the mechanical pump fail. Most pilots turn the back up off once they are at a safe altitude.

[mannanj]

What Bob says is right.

Some have an irrational fear of hot starts in an injected engine. Once you get the procedure down, it's a non issue.

With an injected engine, you can save on fuel by going lean of peak on the egt temps. Much harder to do on the carb, if at all.

The injection is just a more efficient way of doing things in my opinion.