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03 F-150 Heritage, No power at fuel pump.

Tiny
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  • 2003 FORD F-150
  • 150 MILES
Hi guys, Ive got an 03 Ford f150 Heritage truck V6, no power at fuel pump, checked all relays and fuses also, checked the inertia switch on ride side kicker panel was told needed voltage on both sides, no power there either, the old pump was bad, I bench tested it bad, , bought a new one, but cant get power to it, any ideas? Thanks.
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Monday, July 23rd, 2012 AT 3:34 PM

19 Replies

Tiny
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Check the inertia switch for power key for only 2 seconds. Power will return cranking.

If not, back up to the relay and check for power at 2 terminals. The pcm grounds the relay.

If no power, possible ignition switch or fuse.

Roy
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Monday, July 23rd, 2012 AT 3:52 PM
Tiny
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Going to check right now, wasnt aware of the 2 sec window on inertia switch, I only found power at one terminal on relay, first time I checked.
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Monday, July 23rd, 2012 AT 4:18 PM
Tiny
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Just checked the inertia switch, within 2 sec window and crank, no power going to recheck all my fuses and relays, You mentioned power on two terminals at relay?
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Monday, July 23rd, 2012 AT 4:28 PM
Tiny
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It look s like there are 2 fuses for the relay

Roy
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Monday, July 23rd, 2012 AT 4:34 PM
Tiny
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I checked the 2 fuses and 1 relay all have power I understood im suppose to have power for two secs upon ignition ON at relay terminal 87open circ to 87close circ when grounding? NO power at inertia switch on two second ignition key on on test.
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Monday, July 23rd, 2012 AT 7:36 PM
Tiny
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If you can energise the relay, see if it powers the pump.

Roy
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Monday, July 23rd, 2012 AT 7:52 PM
Tiny
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About to check that, let me see if I can energize the relay, what about the inertia switch, and doesnt the ignition switch send power to pump also?
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Monday, July 23rd, 2012 AT 8:24 PM
Tiny
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Yep but you need power to the switch before it can send power anywhere
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Monday, July 23rd, 2012 AT 8:54 PM
Tiny
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I jumped off term 86 to 85 with pigtail, I did get 12 volt to pump plug, but unable to shut off voltage with key at pump plug, did have continuity to ground on black line, and constant 11.5 volts on yellow lead at pump plug, inertia switch jumped out also, .
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Monday, July 23rd, 2012 AT 9:39 PM
Tiny
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I wish you had a scan tool as you could energise the fuel pump relay from the scanner to verify control circuits before condemning the pcm

Roy
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Monday, July 23rd, 2012 AT 11:22 PM
Tiny
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I have an OBDII scanner, can I I energize the relay from their? And verify operation of the pcm as You said, im grasping at straws now, I see even the cam position sensor can affect my pump power and the ignition switch too correct?
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Monday, July 23rd, 2012 AT 11:31 PM
Tiny
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Cam sensor, no. What kind of scanner?

Roy
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Monday, July 23rd, 2012 AT 11:36 PM
Tiny
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Ive got a simple scanner to read codes with, well so far ive tracin wires from the pcm connection to inertia switch, read the connection at pcm often has corrosion and can cause problems, also looking for ground issues, based on schematic, if I energize the red lead at relay it should pull relay in and energize the line out to inertia switch which in turn goes to pump, ?
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Tuesday, July 24th, 2012 AT 5:26 PM
Tiny
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What pin at the pcm did you check as the pcm controls the ground control for the relay?

Roy
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Tuesday, July 24th, 2012 AT 5:30 PM
Tiny
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So if I got this rite the pcm sends ground only? Light blu/org comes from pcm to meet red from ign switch which in turn pulls in the light blu/org, from fuse 19 constant hot, to drk green/yel to send voltage over via inertia switch to pump?
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Tuesday, July 24th, 2012 AT 5:41 PM
Tiny
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When testing at pcm, connector attached, I would check the color coded wire or? Im looking for schematic of pcm output connector
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Tuesday, July 24th, 2012 AT 5:48 PM
Tiny
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It is a light blue/orange wire at pin 80 on the pcm.

Roy
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Tuesday, July 24th, 2012 AT 5:54 PM
Tiny
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Tested lightblue/orange from pcm connector to ground stays open, checked continuity from pcm connector to relay end of lightblue/orange wire have solid continuity, Red wire opposite to lightblue/orange is grounded, I think that goes to switch, pcm not grounding or pulling in ground from red wire to complete circuit and send power out via relay?
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Tuesday, July 24th, 2012 AT 6:17 PM
Tiny
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If you have power at the relay see if it is coming out going to the fuel pump. One of the pins may have slid out in the fuse box or you have corroded or broken wire from relay to inertia switch
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Friday, July 10th, 2015 AT 1:00 PM

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