87' Bronco 2 2.9L 4x4 fuel pump wiring

JoKuchta · #1 (**permalink**) 09-24-2009, 07:54 PM

I have a 87' ford bronco 2 2.9l 4x4.
The vehicle started fine once a month in storage until recently.
Turned the ignition and the motor will turn but not run.
Replaced the relay for fuel pumps.
Hardwired both pumps low pressure intank and high pressure rail mounted and they both will run with direct power.
Dropped the tank, and I have 4 wires on the connector.
from left to right facing tank from from front of vehicle
Black - Yellow w/ white stripe - Pink - Orange
now the black i belive is the ground
on the yellow/white wire I get a reading of 0 volt to 10 volt fluctuating on off ever second with the ingnition on.
no reading to either pink or orange..
So I belive the yellow/white wire is power to pump...
upon trying to trace where the yellow/white wire leads I found it goes all the way up thru the frame into a wire bundle i belive leadsthru the firewall... I have pulled the fuse panel and checked the inertia switch and computer. yet I cannot find where the wire has gone...

I have also reset the inertia switch just to be sure... still nothing

I have a haynes manula for the vehicle but it doesnt display any wiring diagram for the connector to the pump nor does it list a yellow/white wire anywhere....
all this wiring is stock and never been tamperd with until now.
can anyone help me in locating a diagram or maybe providing some information as to where this wire ends up so I can continue to trace it until I find where i am losing power to the pump?

87 XLT · #2 (**permalink**) 09-25-2009, 07:39 PM

Yellow/white is voltage from the fuel gauge. The sender in the tank varies the resistance on this wire.

Heres what you need to do:

See this link
http://superhighoutput.com/tech_view.php?id=5

Once you have your jumper connected & the key on see if you have 12 volts at the inertia switch.

Heres how it's wired:

Pump relay to inertia switch on orange/light blue

Inertia switch to connector C160 on pink/black

Connector C160 to C161 & on to the pumps on black/pink.

Solid black is pump grounds

Solid orange is the fuel gauge ground.

BTW, the pump circuit only stays hot for 2 seconds each time you turn the key. Kinda hard to test in only 2 seconds. Thats why you need to see the link and run the jumper.

JoKuchta · #3 (**permalink**) 09-25-2009, 10:28 PM

Thank you for the responce. You have saved me quite a bit of head scratching.
I will try this out tomorrow and post the results.
thanks again

87 XLT · #4 (**permalink**) 09-25-2009, 10:43 PM

Glad i could help, good luck with it.

JoKuchta · #5 (**permalink**) 10-01-2009, 08:45 PM

I finally got around to preforming the tests you suggested... it turns out I had power to the inertia switch but not out of it...
the vehicle has never been in an accident nor has it ever really been driven off road that rough but i believe the problem occurred from corrosion building on the inertia switches internal components while sitting unused.
Upon replacing the inertia switch, power to both the low and high pressure pumps was restored and she's running great.

Thanks again for for the help!
~Jo Kuchta

JoKuchta · #6 (**permalink**) 10-02-2009, 04:31 PM

So the ABS light on the dash wont turn off. If i remember correctly it has been this way since the vehicle was purchased. I dont know where to start on trouble shooting this. any help would be greatly appreciated!
Thank you,
Jo Kuchta

87 XLT · #7 (**permalink**) 10-02-2009, 05:37 PM

Thanks for the update on the fuel pumps. Good to see you got that squared away.

The PITA ABS can be tested by removing the cover over the ABS control module which is just behind the drivers door pillar.

When the ABS warning light comes on leave the engine running, ground the pig tail at the control module and count the flashes on the warning light. That will be your trouble code. Post it here.

JoKuchta · #8 (**permalink**) 11-01-2009, 02:57 PM

Thank you for reply!
Took me a while to get around to it as deer season came upon me and I've been busy running through the woods...
I tested the PITA ABS as per your instructions and the error light flashed 9 times...

~Jo

87 XLT · #9 (**permalink**) 11-01-2009, 03:28 PM

Glad to see your priorities are in the rght order. FIxing the ABS nonsense is no where near as important as a good hunting trip. LOl

ABS trouble code 9:

"Yellow antilock lamp flashes 9 times & red brake warning lamp is off."

"Disconnect sensor harness connector from the sensor on the rear differential. Check for resistance at the 2 sensor pins. Place the ohmmeter on the 20K scale. If resistance is over 2500 ohms, replace the sensor."

If the sensor tests good, i'll post the rest of the test routine.

JoKuchta · #10 (**permalink**) 11-02-2009, 01:04 AM

Pulled the speed sensor in the rear differential and it appeared to have quite a chunk taken out of the magnetic area... purchased a replacement sensor and i am draining the diff right now... plan on pulling the pumpkin and seeing if there is something loose in there that may be getting caught in the exciter and possibly marring the sensor... if i dont find anything there i was told to check the play in my rear drive shaft as too much could lead to a large bump jarring the entire diff... i dunno how this is gonna pan out but I will post the results tomorrow after I get to it.
Thanks for the quick response!
~Jo