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My 86 bronco will start then die with in seconds .I replaced fuel filter .Replaced the fuel pump in the gas tank . Replaced the fuel relay . On the fuel rail i checked to see if i had fuel presure i have alot of air very little fuel . So i cycled the key about 10 times .Got it to start it ran for about 3 mins & died again . Also new battery . Anyone got any ideals ? Thank u
 

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1986 Eddie Bauer Bronco 5.0L AOD Full length headers, no cats annoying Flowmasters
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Sounds like a fuel pressure issue, pick up a fuel pressure guage and it screw right on to the Schrader valve on your fuel rail & see what your fuel pressure is.

Turning the key to run, you should hear it fire the fuel pump. You said the in tank pump is new. That is the low pressure pump, but I did not hear you mention the secondary pump, which is the high pressure fuel pump, which is about even with the firewall, on the (Drivers side) inside of the C-channel of the frame.

The normal fuel pressure range is 35-45 psi. So test pressure at the shraeder valve on the fuel rail.
 

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Discussion Starter #3
Sounds like a fuel pressure issue, pick up a fuel pressure guage and it screw right on to the Schrader valve on your fuel rail & see what your fuel pressure is.

Turning the key to run, you should hear it fire the fuel pump. You said the in tank pump is new. That is the low pressure pump, but I did not hear you mention the secondary pump, which is the high pressure fuel pump, which is about even with the firewall, on the (Drivers side) inside of the C-channel of the frame.

The normal fuel pressure range is 35-45 psi. So test pressure at the shraeder valve on the fuel rail.
Yes it does have another fuel pump on the frame . Does it need it to run ? Never seen a car that had 2 fuel pumps . Is there a way to see if its bad ? Thank you .
 

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The truck needs both fuel pumps to run. The low pressure pump gets it out of the tank and the high pressure pump makes useable pressure for the injectors. Like Rob said, checking the fuel rail at the schrader valve will answer that question.

Sent from my Hush-98 comlink
 

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Discussion Starter #5
Also another thing happen today my son inlaw wanted to check inside the dist cap . The key was on & he took the dist cap off & reach down to pull the rotor out & got nail very hard with juice .He said it felt like a 115 volts . I never heard of that . Any ideals on that .? wounder if that is normal or maybe that has some thing going on beside fuel . Thanks
 

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Discussion Starter #6
The truck needs both fuel pumps to run. The low pressure pump gets it out of the tank and the high pressure pump makes useable pressure for the injectors. Like Rob said, checking the fuel rail at the schrader valve will answer that question.

Sent from my Hush-98 comlink
yes we will get a fuel PSI and see . All we are getting now is little fuel & air out of that fuel rail . Now with the dist thing today seems like there a whole new can of open worms to solve .Thank u
 

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Yo BBICWill,
Ditto on fuel pressure test.

Try a Self Test for Diagnostic Trouble Codes by my pal, BroncoJoe19 @ Code Reader.....

PCM stores the Self-Test program in permanent memory. When activated, Self-Test checks the EEC system by testing memory integrity and processing capability, and verifies that various sensors and actuators are connected and operating properly.

Inspect the air cleaner and inlet ducting to throttle body.
Check all engine vacuum hoses for damage, leaks, cracks, blockage, proper routing, etc. Check EEC system including the wiring harness for proper connections, bent or broken pins, corrosion, loose wires, proper routing, etc.
Check the Powertrain Control Module (PCM), sensors and actuators for physical damage, such as IAC, TPS, ICM, MAP,, etc.
Check the engine coolant for proper level and mixture.
Check the transmission fluid and engine oil level and quality. Make all necessary repairs before continuing with SELF TEST.

The engine temperature must be greater than 50° F for the Key On Engine Off (KOEO) Self-Test and greater than 180° F for the Key On Engine Running (KOER) Self-Test.
If possible, run it around to heat the engine up and shift thru all gears including Reverse. Make sure A/C is off and transmission is in Park (automatic); or in Neutral for a Manual and; release clutch. Then turn off engine, all accessories/lights (close driver's door) , etc.

Do KOEO test First. Post Code(s) here according to KOEO and KOER (if possible).

A helper can assist you by counting the codes. Some use their smart phones to record them.

BEWARE OF FAN, BELTS, PULLEYS, HOT HOSES, IGNITION HIGH TENSION WIRES, AND ENGINE COMPONENTS⚠

Or ask local mom and dad parts stores if they will test it for you.

Or purchase a coder reader such as Equus 3145 Innova OBD I Code Reader for Ford EEC IV Engines at Walmart & most parts stores.
□⊙□
87-89; Fuel Injected Engines - "...Two electric pumps are used on fuel injected models; a low pressure boost pump mounted in the fuel tank and a high pressure pump mounted on the vehicle frame. The low pressure pump is used to provide pressurized fuel to the inlet of the high pressure pump and helps prevent noise and heating problems. The externally mounted high pressure pump is capable of supplying 15.9 gallons of fuel an hour. System pressure is controlled by a pressure regulator mounted on the engine...

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..."
View attachment 160187

Diagnostic Link Connectors for EEC-IV processors 84-86 (red) located on R wheelwell near starter relay.

Connect FP Relay (terminal A) to any ground (like terminal E) to force the fuel pump(s) on when the key is in RUN.

Pressure Test Gauge Overview & pic;
View attachment 160188
"...To test the fuel pressure you’ll need this tool. You will need to screw it onto the schrader valve on the top of the fuel rail, it looks like a tire air valve stem. After attaching the fuel pressure tester, run the fuel pump for 10 seconds. Check that the pressure is within specs, and it doesn’t leakdown more than 5PSI within 60 seconds after pump shutdown..." by Ryan M.
Most parts stores loan the test kit for a refundable security deposit

MIESK5 NOTE; from Ford EVTM; The Control Module (PCM) runs the pumps}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}.


86-87 Bronco Single-Function Fuel Reservoir aka accumulator Fuel Flow:
160189

160190


"...Fuel flows in through the larger tank-side supply nipple from the in-tank pump to the inlet check valve, which allows it into the reservoir. As the cup fills, fuel moves through the filter, up the pickup tube, & out the larger engine-side supply nipple. Unused fuel enters the engine-side return nipple, mingles with any unused fuel coming through the check valve from the reservoir, and exits the tank-side return nipple.
The only fault that would cause a noticeable problem would be for the inlet check valve to stick closed, blocking any fuel from entering the reservoir, but this isn't likely. With the cup removed (have a replacement cup O-ring in-hand before attempting), a sharp pick can be used to pull the valve downward & open. The valve cannot be removed from the reservoir body.
A more common fault (but less noticeable) is for the check valve O-rings to fall out or split, reducing the pressure to the frame pump. This might make the engine slightly harder to start, especially after the tank runs dry.
The Ford engineering number on the filter is E6TZ-9365-A. A reservoir marked "DO NOT REMOVE CUP" does not contain a filter. For a replacement O-ring for the cup, buy a NAPA 3268, Fram CG3862, or equivalent filter."
"Dual fuel pump systems must have a fuel accumulator between them. Fuel accumulators store fuel from the low pressure pump for the high-pressure pump. Storing fuel is a great idea for rock crawlers, as the accumulator holds a reserve of fuel, just in case gravity temporarily affects the gas tank. Accumulators also equalize fuel flow between the pumps. If one pump is pushing over 75GPH and the other is only flowing 50GPH, something has to give. Once the accumulator is full, excess fuel flows out to the return fuel line, and back to the tank. This keeps the low-pressure pump from stressing the high-pressure pump." by Ryan M
 
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