Well, here i am again. Problem: When I turn key on can hear BOTH pumps kick on. The High Pressure has an audible "click" sound and I can hear the In Tank pump click and then "spin up" for bout 2 seconds. It'll then Crank and Run for bout 15 seconds and then the Engine quits. Out of Fuel? Afterwards, I can turn the key on and hear both pumps "click" and that's all. Wierd thing is at the plug going into the tank I'm getting 12v. On the bottom of the sending unit where the wires run to the Pump I'm getting an intermittent (1 second On and Off) reading of 8 volts. Relay is new and appears to be working. I can wait till the fuel runs back in the tank(I think)bout 30 minutes go out try to crqnk it and it does the same thing...like it's not getting a continuous supply of fuel. I don't get it! Had to break the plug to the tank into pieces and plug the wires directly to tank as the plug was dry rotted and cracked and none of the terminals(female)were tight. Anyways, from the left to right going on the sending unit Ive got BLACK, PINK AND BLACK, YELLOW, and then ORANGE. Are my wires in the correct order? What would cause it to run for 15 seconds and then quit? Anybody have any ideas? I am exhausted messing with this thing! It sat for 4 months, I finally got the new heads and gaskets, bolts, etc. Found out the Coil died while sitting, then the Fuel system messes up. Have new Pump, Sending Unit, Fuel Filter, and Relay now. Bout had it fellas!

88Bronco II, 2,9ltr.-5speed

 

Sounds tough You might try the inertia switch,located under the passenger side carpet at the top, it can do weird things as in intermittent. The test plug located at the back of the passenger side fender well has a terminal that you can ground and make the pump run continuously, but it won't work if the inertia switch is bad. I assume your fuel filter is good, have you checked fuel pressure?

 

Interesting. Just wondering to the guru's of the Bronco II's... Does the fuel pump circuit use the ECU at all? I seem to remember years and years ago any wonky connection to the ECU would create all kinds of interesting stuff to happen...or in this case? Not happen at all? (ie: Fuel pumps not working right). Something about removing the connector, and replacing the connector a few times to ensure tight connections?

Also, if the system fails to see the engine is 'running' could shut down the pumps..This is gonna be tough. I'd check my manuals, but they are with our '89 project on the other side of town.

Not sure if it helps?

S-

 

4wheelingearheads -> fuel filter

 

As lawnboy58 said, ground pin #6 of the test connector with a gauge hooked to fuel manifold.
Turn on the key and you should get about 42 psi pressure.

Let us know what you get.

 

cycle the key on and off a few times then try to start it

 

Well, decided to check the Inertia Switch and then the Computer Connections. Pulled the plug off the Inertia Switch and jumpered the Plug and now I got Fuel Pumps! The Plug was wore out just like the one connecting to the sending unit on the tank so I cut the plug off and twisted the two wires together and taped them with electrical tape. Know that's a NO-NO in the Professional world but to be honest; I've spent enough money on this little truck the past 10 months where I could've bought another one like it that was actually running and in good repair. Good thing bout it though another 10 months like the last and i'll be a Bronco II Guru! (HA HA)

88 Bronco II, 5spd. Auto Hubs
31X10.5X15 Mud Kings
Noble. LA.

 

Sounds great that you've found the problem!!

If I can make a possible suggestion? If the current inertia switch as contacts that you can actually get to? And the switch itself is fully functional (testing with a multi-meter) Why not just solder the wires to the switch lugs? Seems that would ensure the safety of the design, and remove the need for the plug.

Kinda guessing with it, as I've not found ours yet LOL. So I'm not sure if this is possible.

S-