90 Bronco fuel problem

rpasko89

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Sep 18, 2011
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Hello. i am trying to fix up my bronco . its a 90 351w, v8 . The only problem it has is initially starting. you have to turn it over at least 4-5 times. by that i mean put the key in it wait for the fuel pump to kick off. Once you do that a few times, you start her and once she is running for the rest of the day and she will start fine. Any ideas? Thanks

 

miesk5

96 Bronco 5.0
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yo rpasko89, Welcome!

First, do a Self Test for Diagnostic Trouble Codes (DTC)s by my pal, BroncoJoe19

Look Codes up in my broncolinks.com site using the new Search function if in a hurry today.

And Post em here according to

KOEO

& KOER

--

Does starter turn over well?

or is it heesitant to turn over the engine?

Have starting & charging sys checked for free at a local parts store anyway

When turning ignition key, is it free to turn and engage well in start, run, accessory positions?

Guesses;

EEC Power & fuel pump Relays often go bad;

Eziest checks first;

Relay, EEC Power (BROWN Connector) next to the FP Relay (GREEN Connector), Trailer Tow Relay (Grey Connector) & EEC Test Connector pic in a 90; on driver's side fender apron to the rear of the Airbox



Source: by SeattleFSB (Seattle FSB) at SuperMotors.net

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..."

MIESK5 NOTE; from Ford EVTM; The Control Module (PCM) runs the pump for one second when it receives an ignition- on signal. It also runs the pump as long as it receives a PIP signal from the Hall-effect devices (inside the Distributor), 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}.

Testing & 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...'87-95 (black or gray) located under L hood hinge under EEC TEST cover. (WPT-743 & WPT-352"



Source: by Steve83 (Steve, That dirty old truck) at SuperMotors.net

 
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