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Randall C
Randall C, ASE MasterTechnician
Category: Ford
Satisfied Customers: 12835
Experience:  35 years ASE Master Tech, Diagnostic , Electrical Specialist
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1989 Ford f150: voltage..the fuel pump regulator and ignition switch

Customer Question

I'm having fuel pump issues with a 1989 Ford f150 where I'm not recieving voltage to my fuel pumps...I replaced the fuel pump regulator and ignition switch still no luck.
Submitted: 6 years ago.
Category: Ford
Expert:  Randall C replied 6 years ago.
Hello, a few questions. What size engine? is it 4x4 or 2wd? what exactly have you changed? pump, relay, fuses etc. List all. LMk thanks
Customer: replied 6 years ago.
I have a 5.0 l 4x2 and i have replaced the fuel filter, relay switch, ignition switch.
Expert:  Randall C replied 6 years ago.
Thnaks, I had to ask because in your first sentence, you stated you replaced fuel pump regulator> let me pull some diagrams and see what I can come up with . In the meantime, do you have a testlight?

Edited by Tracer on 12/10/2010 at 10:53 PM EST
Customer: replied 6 years ago.

I have a Voltage meter.

 

Expert:  Randall C replied 6 years ago.
test # XXXXX I need you to remove the fuel pump relay. Turn key to RUN. probe the relay terminals at relay plug and I need to kow how many terminals have 12 volts. LMk when you can. thanks
Customer: replied 6 years ago.
2 terminals have 12 V
Expert:  Randall C replied 6 years ago.
Thanks. let me keep moving to next few diagrams, back shortly
Customer: replied 6 years ago.
I did test one of the fuel pumps and it tested ok, I'm just not geting any voltage.
Expert:  Randall C replied 6 years ago.
Got it thanks.. and working on it. Just takes a little time as I have to pull individual diagrams , review then type back to you. I am going to put this through as answer but.. may not be the answer so.. you can still get back with me.
Are you aware that the truck has a 911 fuel cutoff switch called the " inertia switch", Do you know wher it is and have you reset it or jumped it? LMk thanks
Customer: replied 6 years ago.

I've heard of this switch but I don't know wher it is.

Expert:  Randall C replied 6 years ago.
I know.. but will look to see if I can find picture of location
Randall C and 10 other Ford Specialists are ready to help you
Expert:  Randall C replied 6 years ago.
Ok, it will be a small plastic box with a button persay on top. It is near the E brake pedal assy under dash. It will have 2 wires going to it. I would say its about 2.5" tall. You need to push the button on top and if this does not work, use your meter and probe one of the wires going to it while cranking or cycling key on/ off every 5-8 seconds. this is the last thing from relay to pump. If we do not have power there. I will then tell you my thoughts otherwise

On F-series, the Inertia Switch is located at the far Left part of the toe-board, near the parking brake assembly. On E-series, the switch is on the passenger side cowl panel, just forward of the right front door.

Typical Inertia Fuel Shut-Off Switch


The inertia switch is used to open the power circuit to the fuel pump, or the control circuit to the fuel pump relay, in case of an accident. The inertia switch must be manually reset by pushing the reset button located on top of the inertia switch.

Operation of the inertia switch is as follows:

A steel ball is held in place by a magnet. When a sharp impact occurs, the ball breaks loose from the magnet, rolls up a conical ramp and strikes a target plate, which opens the electrical contacts.


Expert:  Randall C replied 6 years ago.
hello, are you back to this post now?
Expert:  Randall C replied 6 years ago.
hello, hello, I am back on this post. LMk where you are at with truck. Thanks
Customer: replied 6 years ago.

Found inertia switch and it seems to be ok, by-passed it, but still not working.

Expert:  Randall C replied 6 years ago.
Hve you had a chance to see if you have 12 volts on either wire at the switch while cranking or cycling key?
Customer: replied 6 years ago.
Still no voltage...just before I started having issues I heard a loud humming noise in the engine compartment close to the relay switch.
Expert:  Randall C replied 6 years ago.
Are you sure you have spark? can the engine run if you spray carb cleaner or starting fluid in it?
Customer: replied 6 years ago.
Ingine runs great, thats the fisrt thing I checked.
Expert:  Randall C replied 6 years ago.
ok, I need you tio do a test. Pull up the fule pump relay, look at the wires. Find the tan/LtGreen wire going to the relay. Cut that wire say a few " back from relay. take the end of the wire still going to relay and find a way to ground it. say run a separate wire to it. You caa go back and splice that wire back later. It is only a ground feed but.. we have to have it cut so we do not backfeed computer. Once you have that wire grounded, the pumps should come on and engine should run. LMk
Customer: replied 6 years ago.
Great! pump is running...but battery is now deadUndecided Looks like we,ve gained some ground, thanks will try again tomorrow.
Expert:  Randall C replied 6 years ago.
I am on each day/off and on, so pls. lmk and we will get to the bottom of this.
Customer: replied 6 years ago.

Thanks'

 

Expert:  Randall C replied 6 years ago.
welcome