Intake fuel pump still getting power with relay disconnected.

[svtcards]

So I recently installed high pressure pump on my current purchased bronco ii.I had everything reconnected,went to turn key to run position and got no fuel. Both pumps appear to be getting power.So I disconnected fuel line that goes to inlet of high pressure pump and turned key to run again.no fuel! Not sure if purging the fuel system is needed after replacing this pump? Also I disconnected fuel pump relay to see if pumps shut off and I noticed the low pressure intake pump appears to getting power still because I hear a click sound coming from tank. I thought disconnecting relay would shut down both pumps! Is this not the case? If not where does in tank power get its power from.I thought both pumps where connected together in some way.let me know.

 

[Uncle Gump]

As far as I know the fuel pump relay powers both pumps. My 86 is wired that way and is reflected the same in the factory EVTM.

I honestly think you would be further ahead to scrap all the factory fuel system and just put a high pressure pump in the tank and make some new lines. Maybe even an access hole in the floor over the sending unit. I did that to mine and the info is in my G-Unit build thread.

 

[RonD]

Yes, fuel pump relay powers both pumps for sure, unless...........older owner did some rewiring

In tank pump reads like its not working or............you are out of gas


If in tank pump is indeed not working then yes, I would get a high pressure pump and swap it out with low pressure pump in the tank, you need to keep using the same assembly in the tank so the gas gauge still works
And then take out the in line pump and splice the ends together


Up thru 1988 in Rangers/BIIs Ford used the old gas gauge setup and dual pumps, 73 ohms EMPTY-10 ohms FULL
In 1989 Rangers/BIIs got the one high pressure pump in the tank and the new gas gauge and sender, 16 ohms EMPTY-158 ohms FULL

Both used the same 30-40psi Return system with FPR(fuel pressure regulator) on the engine end, so that part doesn't need to be touched, just swap pumps


FYI
High pressure pumps have no suction, so they can not suck gas out of a gas tank
Ford had the in tank low pressure pumps already for carb setups that didn't use mechanical pumps on the engine
Mechanical pumps have GOOD suction, lol

So when Rangers/BIIs went to fuel injection they just added the required high pressure pump outside the tank and let the low pressure pump feed it, many also had a reservoir/filter between the pumps so high pressure pump always had fuel

In the gas tank the high pressure pump needs no suction, its immersed in gasoline................unless you run out of gas

 

[svtcards]

I agree about eliminating all the crap on the frame and install high pressure in tank. At the moment just need it to run.kimda bought bronco ii as a flip so putting to much into isn't something I want to do .unless I decided to keep it of course.just want it running for now. Your probably right about rewiring from previous owner.theres an orange wore rin to constant power from harness from intake area to battery positive right now.not sure what needs constant power from that wire still trying to figure that out. Thanx again for the responses.i ll post pic of wire I just mentioned maybe u could tell me what that actually powers

 

[svtcards]

If I were to change fuel lines to -an fittings what size would I need for fuel line? -4an or a -6an?

 

[sgtsandman]

-4 is pretty tiny. I think -6 would be closer to the proper size. If I remember correctly, the - size represents 1/16ths of an inch. So -4 is 1/4” and -6 is 3/8” OD. The ID is pretty small on -4 and might not provide enough volume. You’ll need to compare the lines you are replacing to the AN lines and see which is closest.

 

[lil_Blue_Ford]

There’s not a lot of stuff for -4an, and at 1/4” may be ok. I went with -6an on my green Ranger. The actual size of the factory fuel line is usually 5/16” I believe. So that straddles the middle and you’re probably better off with -6an for more than one reason.

 

[RonD]

All fuel injected Ranger fuel lines are 5/16" nylon

They commonly used 3/8" fittings for fuel lines running from the gas tank to filter and to the engine
Return fuel lines were usually 5/16" fittings

So fuel lines couldn't be reversed by mistake