2009 iMac and external disc as start up

[AL2TEACH]

I will try to make this short
I was wondering if I can have the iMac use the external disc for starting up all the time, not just for restarts.
When I power the computer up, it must be using the empty internal disc because the screen is blank/grey.
When I power up the computer, pressing the power button and holding the option key down, the recovery disc shows up but not the external. After it restarts showing disk utilities, I close that window and it shows the start up disc window, only the external is there and already selected. I press restart and it opens with the external which is great.

The problem is when I turn it off and power back on, it never uses the external.
I was wondering if it was possible for the computer to power on using the external all the time and bypass the blank internal disc or having to press the option to get to the recovery disc.

Thanks

 

[DeltaMac]

Is your external drive an SSD, or a spinning hard drive?
The initial blank screen likely means that the externa drive is simply a little slow in responding when first booting, so your iMac likely (in a sense) ignores the external drive.
It seems that you are able to boot to a recovery system, which might be on the internal, or the external drive. It's hard to determine that from your info. It can't otherwise be trying to boot from your internal drive -- if it is actually erased, you would be getting a flashing folder/question mark (indicating that no operating system can be found) rather than a blank screen.
If you have a spinning hard drive for your external drive, you might get a more reliable boot using an SSD.
If you are, in fact, using an SSD for the external, you might consider installing that SSD inside the iMac, replacing the existing internal. The USB 2.0 bus is always going to be the "weak link" for booting on an older Mac.

 

[AL2TEACH]

external drive an SSD, or a spinning hard drive?

spinner

The initial blank screen likely means that the externa drive is simply a little slow

it stays blank for some time

able to boot to a recovery system,

it's on the internal

reliable boot using an SSD.

giving it away to people that will not be online, it will be used primarily as a photo viewer.

 

[DeltaMac]

OK... So, I have some random thoughts...
Make sure that you have tried an NVRAM reset? (Reboot, holding Opt-Command-P-R. Continue to hold those 4 keys until you get 5 boot chimes)
Consider replacing the internal button battery (low batt CAN contribute to strange boot issues on some Macs)

Why not reinstall a system on the internal drive?
That can give you the opportunity to erase that internal device, not just erasing the volume.
So, the internal recovery system would be wiped, too.
Reinstalling OS X would then make a fresh recovery system.
The complete wipe and reinstall (including an actual boot system) might (maybe) help out with your boot questions.

Finally, the internal hard drive, even though you are not actively using it for booting, may be getting enough age, or just not as reliable as it was, and now is giving you some difficulties because it is beginning to fail, and causing you problems because it is still plugged in, maybe interfering with the boot sequence.
(and is another reason to consider swapping in another drive)
Or, continue with the work-around for booting, which requires a reboot everytime the iMac is booted.

 

[AL2TEACH]

Why not reinstall a system on the internal drive?

Because it's from 2009 and probably knocking on the door, lol.

They didn't want the puter (they have a dell laptop with windows 97 on it) So, I will erase everything and see if Apple will take it for parts or something.

Many thanks to you