NEED HELP fuel problem

HI guys new to this but I really need some help, I have a 1989 bronco 5.0, I've checked the fire it fires good, I've replaced both pumps, and the engine relay, but when I check the pressure it still reads 0. what am i suppose to do now? I pretty much have no idea where to go with it from here. Mabe it could be the inertia? but I was told they never go out unless your hit, but then again that could be a lie. thanks again.

yo sseipp,

WELCOME!

Operational Sequence; "...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. 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}.

Inertia Fuel Cut-Off Switch (IFS) - it could be tripped or defective (wiring, connector, etc.); someone could have inadvertenly kicked it;

Typical locations for Bronco: firewall, between e-brake & brake pedals in 84-89

firewall, R side of trans tunnel in 87-91

R kick panel immediately below dash in 92-96;

or someone could have backed into your Bronco and tripped it (sometimes on purpose knowing it could case the IFS to trip)

see these "tripped" pics



Wiring Diagram in an 89 from EVTM



Source: by SeattleFSB (Seattle FSB)

Check for power at both sie of IFS

Re your; "...and the engine relay.."

Did you test for voltage at Both FP and EEC Power Relays?

(BROWN socket = EEC power; GREEN socket = fuel pump)

Here is a Wiring Diagram in an 89 5.0, 5.8 & 7.5 (partial at FP relay); miesk5 Note; G801 is located on the LH inner fender behind the headlamp & both pumps Grounds join @ Splices S155 & S903

Source: by Seabronc (Rosie, Fred W) at Ford Bronco Zone Forums http://broncozone.com/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=10092

In Seabronc's diagram, should have battery voltage (over 12v DC) at Brown wire from FP Relay to pumps

if none, then check Red wire from EEC Power Relay

if none, check for voltage at W/LB and P/O @ EEC Power Relay

continue checking ckt

ok. thank you so much!

Ok so i have gotten a brand new PMC, a new EEC relay, and plus everything else i have replaced, but yet the car still wont start, but we know we are still getting fire, so now i dont know what to do.

yo, Too bad about the new parts.

Can someone in your family or friends help you troubleshoot the ckt using the diagrams posted above?

I'll reiterate this info;

Pull the EEC and FP relays and inspect & test

Expect corrosion in sockets and on relay contacts

test your relays by applying 12 V across the small terminals, listen for the click and check continuity across the large terminals. This will rule out the relays themselves being a problem.

Operational Sequence; "...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 EEC-IV . 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 EEC-IV 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." Note: Grounding the FP lead at the DLC will allow the pump to run continuously with the ignition switch on..."

Try a FP Test at the Diagnostic Link Connector;

Connect "Fuel Pump Test" to any ground to force the fuel pump(s) on when the key is in RUN; located under L hood hinge under EEC TEST cover

http://broncozone.com/index.php?app=core&module=attach&section=attach&attach_rel_module=post&attach_id=6766

Pic by BroncoJoe19

Does this operate the Pumps?

Another test is to check the fuel pump relay when cranking the engine over. Not the 2 second run after the key is turned on, but while cranking the engine. If the fuel pump relay kicks on when cranking, the TFI & Stator are good and this will confirm your statements about; "...we are still getting fire"

EEC power relay & Fuel pumps grounds @ G801

miesk5 Note; I BELIEVE G801 is located on the LH inner fender behind the headlamp & both pumps Grounds join @ Splices S155 & S903

Also, try a self test for codes by Joe @ http://broncozone.com/topic/14269-code-reader/page__pid__74587__mode__threaded

Make sure A/C is off and transmission is in Park (automatic) or in Neutral for a Manual & release clutch.

Do Key On Engine Off (KOEO) portion

And Post Codes here

Not certain if this is pertaining to your situation but my 87 had a jumper wire for fuel pump with switch. Friend of mine said b/s took it off and fuel pump wouldnt run. He had me turn key on and listen to pump as he shook wiring harness under hood on drivers side and it turned pump on. Turned out to be a corroded connection in plug to fuel relay switch which he then soldered, reconnected and no problems since. Said older Bronco wiring harnesses were notorious for corrosion.

Good luck