Should there be power to the external fuel pump with key on but engine not running?

 

It's always best to mention the year of the vehicle, but sounds like you may have an 86-88 which has 2 fuel pumps. The internal or Fuel Send Unit or Low Pressure Pump or LPump (and) The external pump or Rail Pump or High Pressure Pump or HPump.

The pumps at Key on should only come on for about 2 seconds. It's easy to hear the HPump but about inpossible to hear the LPump unless you test them separately. So if you hear nothing at all - the first easier things to do:
1) check the intertia switch behind the passenger side kick panel. Lots of people remove it and or bypass it. I took mine apart and cleaned it and tested it 10 times to be sure.
2) swap around the relays under the hood on passenger side. Make sure to remember which one swapped so you know the bad one if something else happens. There is a way to test each one you;ll have to look that up.

There's a few more things to check but those 2 are first and easiest.

 

Actually is a 1990 B2. 2.9 EFI.
Has new in tank pump, removed the external pump gave it a flush, new fuel filter, new plugs. The truck starts and runs. but only for about 10 seconds. going to remove fuel regulator and give it a once over

 

Swapped out fuel regulator. Swapped out relays. Bypassed inertia switch. Still no go. At my wits end

 

1990 doesn't have an external fuel pump. B2 owner's 86-88 like to convert from 2 pumps to 1 pump like 89-90. I would suggest to first make real sure that the pump is functioning. I'm not sure if this test will work for 89-90 but the test is:
Here's what i had to do, but if you only have 1 pump...just skip past Hpump references.

Here's what i did because it's easier than removing the sheild on the Hpump to get to wires. It's also hard to hear the Lpump. So...there is a plug under the apron that is under the master cyclinder that maybe hard to unplug and it could even be greened up causing a puwer issue to one or both pumps. Once you get the plug undone and cleaned up you can at least test the power to the first failure point and then you can test each pump and "hear" each one. You will need 2 jump wires 1ft or less. Alligator clips or even just bare folded over ends may do.

See pic attached
1) Unplug fuel pumps "Y" connector
2) Ground out Pin#6 of ODB1 connector use a small jump wire..
3) Small jump wire from single side/output side of fuel "Y" plug to one side of the input "Y" plug.
3) Turn key to ON position and you should hear at least 1 fuel pump. Turn key to OFF position.
4) Move jump wire to other input of "Y" plug
5) Turn key to ON position and you should hear the other fuel pump. Turn key to OFF.

Tips -
1) with Pin#6 grounded the fuel pumps will continuously run so don't leave key ON for as short as time possible.
2) The Lpump in the tank can be very hard to hear that's why i split this test into 2 parts.
3) Essentially we are testing the fuel relay, ECC, "Y" plug, Hpump and its' plug, Lpump and its' plug all without a voltmeter, however a voltmeter maybe necessary to pinpoint further if you find 1 or both pumps are not working.
4) The 3 plugs get greened up and can cause an issue. The Lpump plug can get crumbly but easyily found at LMC at or other places.

Good luck! It's what i had to do to finnally hear that my Lpump was intermittant due to an improperly installed replacement plug. Paid lots of $$$$ money to 2 dfferent entities an they could not find the problem.

 

1990 does have external Hpressure fuel pump. Sticker on door says it is 1990 and I removed and flushed it

 

I checked another forum and asked "would 89 or 90 have 2 fuel pumps?" Here's the answer i expected:

 

I have an ‘89 Bronco II. Since I couldn’t remember, I went out to look…there is only one fuel pump and it is in the gas tank. Post some pictures of this external pump that you flushed. The fuel lines are nylon so how is the pump connected to the hoses?