95 5.8 fuel pump relay not working

nofearguy09

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Hey guys im having a problem with my fuel pump not working. ive traced it down to the relay since im not getting any juice to the green with yellow strip wire that feeds the inertia switch. i have juice at the yellow wire and the red wire running into the relay.Is  the blue with orange strip wire a ground?? ive swapped the relays out with other ones (kept the EEC relay in since it powers the fuel pump relay) with no success. i can hear it clicking just no juice to the other side. Not sure if this is important either but im not getting power to my starter solenoid from the key. will try to start when jumped at the posts but without the fuel pump running i cant start it. PLEASE HELP!!! I did a whole body and interior swap from an 88 to a 95 (after i rolled it)and havent had it running for over 2 years. just hearing it crank left tears in my eyes haha. ive checked all grounds  that i can find and everything else seems to be working fine. i can take pictures if need be. just need to get this BEAST back on the trails.

 

nofearguy09

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i seem to be getting voltage through that wire though. the test light was very dim when connected. thats exactly what i did with no sucesses. i know the horn relay works since my horn works so now im kinda lost on what to do....

 

miesk5

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yo ok,

Did you pull the horn relay & put it in place of the PCM Power Relay?

Sorry, have to be sure.

Check battery voltage

Red wires to PCM & FP Relays should be battery voltage

BK/Y should be batty voltage

same for Y wire Black wire is ground G100 @ LH front of engine compartment, on upper radiator support

Hopefully, there is no burnt aroma around the driver's kick panel where PCM is located.

Have to go now. Will be back in morning.

 

nofearguy09

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thanks man ill let you know what happens. i will change both relays today and check the voltage at my wires. 

 

nofearguy09

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Still nothing checked both relays. EEC relay is wokring fine but still nothing from the fuel pump relay. I can hear them clicking but no juice is flowing on the fuel pump relay. I pulled out the test light and have a faint glow from the blue/orange wire. Is that supposed to happen?? Thought it was a ground. My multi meter was dead so will get a battery for it tomorrow and check actual voltage. Battery in the truck is brand new.

 

miesk5

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yo

Fuel Pump Circuit Operation

When the ignition is switched to the ON position, it turns the EEC Power Relay on. The EEC Power Relay provides power to the EEC-IV processor and the control side of the fuel pump relay. Power for the fuel pump is supplied through a fuse link or high current fuse attached to the starter solenoid (battery side). From the fuse link or high current fuse, current flow is through the fuel pump relay and Inertia Fuel Shutoff (IFS) switch to the fuel pump. The IFS switch is a safety device used to shut off the fuel pump in the event of a collision. If the IFS switch is "tripped," it must be reset by depressing the white or red button on the top of the switch. The fuel pump relay is controlled by the Powertrain Control Module (PCM).

When the ignition switch is turned to the ON position, the fuel pump will operate. If the ignition switch is not turned to the START position, the PCM will shut the fuel pump off after approximately one second. The PCM will operate the fuel pump when the ignition is in the START position to provide fuel while cranking.

After the engine starts, the PCM will continue to operate the fuel pump unless the engine stops, engine speed drops below 120 rpm, or the IFS switch is "tripped."

Are Fuel Pump Relay socket contacts clean?

Test & Diagram at the Diagnostic Link Connector in 84-95; "...Connect FP Relay to any ground to force the fuel pump(s) on when the key is in RUN..." MIESK5 NOTE; from Ford EVTM; The Control Module (PCM) runs the pump{s} for one second when it receives an ignition- on signal. It also runs the pumps as long as it receives a PIP signal from the Hall-effect devices, it continues pump operation even after the key is released from START. If the PIP signals fall below 120RPM, the control module cuts off the signal to the fuel pump relay or the integrated relay control module. The pump will also run when the terminals of the fuel pump test connector are jumped. the Control module signals the pump when it receives a CRANK signal, and when the Control module gets PIP signals that the engine is running. the pump does not run if the PIP indicates the engine is not running even with ignition ON {except for that first one second}.

Source: by Steve http://www.supermotors.net/registry/media/245234

Troubleshooting w/Wiring Diagram in 94-95 F Series; Miesk5 note that this is for F Series w/dual tanks & pumps; the R/Y wire from Inertia Switch to Fuel Pump is PK/BK on Broncos

Source: by seijirou at



Disconnect battery and check for continuity on LB/O wire from FP relay to PCM pin #22

EEC IV Connector Pin Diagram

http://web.archive.org/web/20131229163930/http://oldfuelinjection.com/images/eec04.gif

by Fireguy50 (Ryan M)

EEC Connector Pin Outs LEGEND, Bronco & Ford Truck & Van: 4.9, 460, 5.0, 5.8; by Ryan M (Fireguy50) at

http://web.archive.org/web/20131029020805/http://oldfuelinjection.com/truckpinouts.html

Connect Battery;

Test for batty power at FP relay DG/Y wire from relay to Splice

S139 Engine control sensor harness, near T/O to powertrain control module (PCM)

 
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nofearguy09

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ill post some pictures today when i get home and test out the LB/O wire. all connections are shiny clean. I don't think i have the Fuse thats attached to the starter solenoid but im pretty sure its always been like that (since it use to run). when it says connect the fuel pump relay to any ground should i just use jumpers to test that or how would i go about doing this?? on the back of the relay i actually have two DG/Y wires coming out of the same spot.

 

miesk5

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yo,

Use jumper wires

Both DG/Y wires should show batty voltage w/FP relay energized

 

nofearguy09

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So i jumped the ground wire in the EEC test connecter and the pump kicked on. Jumped the car at the starter solenoid and it started right up. FINALLY AFTER 2 YEARS and it started like it had been running the whole time. So I did a voltage test too on the G/Y wire from the relay and I'm only gettin 9 volts. so do I have a bad ground somewhere? ?

 

miesk5

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yo,

GGGGreat!

Prob bad ground or connector terminal corrosion.

And I assume Yellow wire to FP Relay is battery voltage?

If Not start testing for battery voltage and inspect Battery Terminals (+ and Neg) cables to frame and engine,, and all the way to FP relay

One Connector is C202 @ LH rear of engine compartment, in safety wall (A8) Terminal: 7 In-Line

Here is a diagram showing C202 & C205 location in engine bay by Mikey

http://www.supermotors.net/registry/media/897688

C202 Pin Diagram by Steve at http://www.supermotors.net/registry/media/909442

you might be able to pierce it there at the firewall to check voltage

The fuel pump gets it ground from G100 which is on the LH front of engine compartment on upper radiator support. If that ground is not "grounded" it could affect both the pump and the fuel level sender. Loosen the nuts on the ground, sand them so they make a good connection to each other and to the body, tighten back up. by Mikey

G100 & G104 (tied together in diagram); G100 @ LH front of engine compartment on upper radiator support; G104 @ Rear of LH fender apron near hood hinge and 4WABS Test Connector (RED);

Frame & Battery Ground pic in a 93; "...With the wheelwell gone, it's easy to inspect the frame ground, just inboard of the spring tower on top of the frame rail. The battery ground cable is stripped ~3/4" and a tab is soldered on so it can be bolted to the frame;

http://www.supermotors.net/getfile/770502/02groundframe.jpg

Intake Manifold to Block Strap Ground Location in a 96 5.0 is between 2nd & 3rd plugs on passenger side;

 
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nofearguy09

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Sorry I never got back to you. Turns out I didn't have the pcm connection and main wiring harness connection from engine bay to interior tightened all the way. Some of the pins weren't getting a connection. Once it was all tight it ran great. Till a few days later when the rear end exploded on me. Then it sat for about a year untill recently. Got that all done and now my fuel pump isn't kicking on. I'm getting power to the relay but it's not working. Relay is good and checked with the horn relay to be sure (also good). I jumped it with a wire and got power to pump (the pink wire at fuel tank)but still nothing. Is my computer not allowing the relay to work because the pump is burnt out??

 

Seabronc

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Check you inertia switch, sometimes they pop with no apparent reason or from a sudden jar.

:)>-

 

miesk5

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Yo,

Ford describes terminal back-out for your case... umay have to try ford's "wiggle test"

Grasp harness and twist or shake

 
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nofearguy09

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All wires all fine and in place. Inertia switch is fine. Tried the old wiggle test and the knock on the tank test. If i get power all the way back there by jumping it with wires at the relay and it's still not kicking on the pump then the circuit can't be completed and the pcm knows this so it keeps the relay from sending juice to the pump?? That's the only thing I could see why the relay wouldn't be working

 

Whipsaw

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This thread helped me get my 1993 Bronco, 5.8L V8 up and running.  It stopped running, I swapped the horn and fuel pump relay, and it ran, once.  Then no start... after another month and time to troubleshoot, no power to the fuel pump (no 1-2 seconds with ignition key to 'on').  I cleaned the grounds behind the left rear tail light and by the inertia switch in the passenger kick panel.  Checked voltages, 12V at the 20A fuse and at the relay, then no voltage from the PCM to close the relay.  Came up to research and you mentioned above to swap the horn and PCM relay, which I did, and boom, heard the pump spin up and she started!  Will be replacing more relays...  Thanks again! 

 
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