Help w/ High/Low Fuel Pump BroncoII

[pinaydyosa]

Hello Everyone, I'm needing to see if anyone can help with an issues my Bronco II is experiencing. I have a 87 bronco II that my dad is currently fixing for me. We discovered that it has two fuel pumps; a high pressure and a low pressure. While the high pressure was present when we popped the hood the low pressure was absent. Currently we have both on the truck but can not seeming get the low pressure to pump/work. I'm wondering one if anything is possible for me to do or check w/ the lower and two if it's essential to have both pumps connected to have the truck function. As of now the lower doesn't read anything...as if it's not functioning. But then again we can not find anyone around who know's what the pump is suppose to read or when or how it's suppose to function in the truck. Any help in this matter would be greatly GREATLY appreciated!..Thanks

 

[89Bronco58]

high pressure is your in tank pump and is used as a pusher, low pressure is on the frame rail and is a helper mainly to move the fuel the rest of the way to the motor, if it doesnt work, you should just replace it, and yes its essential

 

[pinaydyosa]

Addition: Ok let me correct my questions; after consulting w/ my father he told me what questions to post specifically.1. How do you tell if the low pressure fuel pump is working?

2. How can I test the low pressure fuel pump to tell IF it is working?

3. If I disconnect the line between the High and Low pressure fuel pump (note: low pressure pump is located in tank) when I turn key switch should the low pressure pump still push gas out of the tank? :blink:

 

[Justshootme84]

Yes, the low-pressure fuel pump inside the tank will normally make some noise (humming/buzzing). If it doesn't come on with the iginition key, use a test light or voltage meter to check the wiring for power to the pump. Check the fuse, too. The pump should flow enough gas when it's powered and running to run a decent flow through the lines, so your method of unhooking the line before the other pump will work. The high pressure pump on the frame rail gets the pressure up for the fuel injection to work. there may be some troubleshooting tips in the How-To and tech articles forum. I have a link posted there for Ford Explorer tech, but that should also help with your Bronco II. JSM84