Fuel pump! Need help please!
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Fuel pump! Need help please!
I have been trying to get my brothers 1990 Bronco to start for the past 2 weeks. The problem is the fuel pump is not coming on when I turn the key. I am not getting 12v to the inertia switch. I changed the ground cable to the battery, changed the eec and fuel relays, and put in a new ignition control module and still no luck. The truck was hit by another vehicle which tripped the inertia switch. I reset it and the truck ran fine for 2 weeks, then it wouldn't start. I cut the wires at the inertia switch and wired them together bypassing the inertia switch, still no luck. I ran a direct wire from the battery to the wires where the inertia switch was and the fuel pump will run. I tried checking the ecc for codes by grounding the self input, but I don't get any flashing check engine light. The check engine light comes on but I am not getting any codes, I think because the fuel pump doesn't come on when I turn the key. I get a reading of 12v at 1 wire on the fuel relay and 12v on 1 wire at the eec relay. I am getting 12v to the red wire on the ignition coil. The green and yellow wire coming from the engine to the inertia switch I am getting a reading of 0.28v. This problem is driving me crazy!!! Any and all ideas would be greatly appreciated. Thank you and have a great day!!
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
You have the answer in the question.
Back trace this wire and find out where it is damaged. Its fed by the fuel pump relay. If the relay is good, you can bypass the relay by jumping the YELLOW and the DK. GREEN YELLOW wires together. If there is still no voltage trace the YELLOW wire back to the fusible link at the start solenoid. Replace the fusible link if necessary. The fuel pump needs battery voltage (11.5-13 VDC) to function.
Originally Posted by iwkr40
The green and yellow wire coming from the engine to the inertia switch I am getting a reading of 0.28v.
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Originally Posted by greystreak92
The interia switch is typically up under the driver's side of the dash on the firewall behind the parking brake pedal assembly.
Lead Driver
Joined: Sep 2002
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From: Gateway to the West
Yeah, I haven't gone looking for the one on the wife's '05 Pony yet... but then I shouldn't have to right?! Had the pleasure of driving it for the past week or so since the Bronco is down with a case of torque-converter-itis.
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Joined: Jun 2004
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From: San Antonio
Im having the same problem. I switched the ignition module on the distrub, the coil and both relays. wellin chaniging the module i moved the cap and rotor and screwed the timming. Now it wont turn over and the fuel pump isnt coming on. please help me too.
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Junior User
Joined: Jul 2004
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From: North Ogden, Utah
I had the same problem when I first bought my 1986 Bronco. The guy could not get it running, and she had been in two fender benders. So I bought it off him for $500. The fuel pump would not turn on and after replacing both the EEC and Fuel relays, it would still not turn on. When I tried to scan for codes both the KOEO and KOER test would do nothing. A friend of mine suggested to replace the computer, which I found at the salvage yard for $25. After that she ran well and started right up. I had to replace a few things like the O2 sensor and egr valve but other than that it fixed my problem. If you can find one for a good price I would try that.
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Originally Posted by greystreak92
You have the answer in the question.
Back trace this wire and find out where it is damaged. Its fed by the fuel pump relay. If the relay is good, you can bypass the relay by jumping the YELLOW and the DK. GREEN YELLOW wires together. If there is still no voltage trace the YELLOW wire back to the fusible link at the start solenoid. Replace the fusible link if necessary. The fuel pump needs battery voltage (11.5-13 VDC) to function.
Back trace this wire and find out where it is damaged. Its fed by the fuel pump relay. If the relay is good, you can bypass the relay by jumping the YELLOW and the DK. GREEN YELLOW wires together. If there is still no voltage trace the YELLOW wire back to the fusible link at the start solenoid. Replace the fusible link if necessary. The fuel pump needs battery voltage (11.5-13 VDC) to function.
Lead Driver
Joined: Sep 2002
Posts: 9,182
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From: Gateway to the West
iwkr40,
We are dealing with a 1990 model right? I'm puzzled since my wiring information has not steered me wrong before now. According to the the information I have, the power for the fuel pump relay circuit feeds from a YELLOW-wired fusible link {20 gauge BLU W}(one of NINE) beginning at the start soleniod on the passenger inner fender. That yellow wire continues on to one of the "switched" terminals on the fuel pump relay. From the relay, the circuit continues down a DK. GREEN/YELLOW (which may appear dk. green/orange after being in the truck for 16 years) wire to BOTH the inertia switch AND pin #8 on the EEC computer. If you remove the fuel pump relay, do you have battery voltage at the YELLOW wire when the key is "ON"? The fuel pump relay should have four wires extending from the connector; YELLOW, LT. BLUE/ORANGE, RED, DK. GREEN/YELLOW. The red and the lt. blue/orange are the power and ground for the coil in the relay respectively and the yellow and dk. green/yellow are the "switched" terminals that are connected when the coil is energized.
ECA (EEC computer) failure is the LEAST likely cause of the problem. Contrary to what some would have you believe, the ECA is the actual root of the problem less than 2% of the time with the EEC-IV system.
We are dealing with a 1990 model right? I'm puzzled since my wiring information has not steered me wrong before now. According to the the information I have, the power for the fuel pump relay circuit feeds from a YELLOW-wired fusible link {20 gauge BLU W}(one of NINE) beginning at the start soleniod on the passenger inner fender. That yellow wire continues on to one of the "switched" terminals on the fuel pump relay. From the relay, the circuit continues down a DK. GREEN/YELLOW (which may appear dk. green/orange after being in the truck for 16 years) wire to BOTH the inertia switch AND pin #8 on the EEC computer. If you remove the fuel pump relay, do you have battery voltage at the YELLOW wire when the key is "ON"? The fuel pump relay should have four wires extending from the connector; YELLOW, LT. BLUE/ORANGE, RED, DK. GREEN/YELLOW. The red and the lt. blue/orange are the power and ground for the coil in the relay respectively and the yellow and dk. green/yellow are the "switched" terminals that are connected when the coil is energized.
ECA (EEC computer) failure is the LEAST likely cause of the problem. Contrary to what some would have you believe, the ECA is the actual root of the problem less than 2% of the time with the EEC-IV system.
Junior User
Joined: Jul 2004
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From: North Ogden, Utah
Yeah I would agree with greystreak, it sounds like a wiring or power distribution problem in this case. Like he suggested check the fusible link at the starter solenoid and work your way through the fuel pump circuit.
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Joined: Apr 2003
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iwkr40, what ended up bein the problem??? im havin the same problem, so im tyrin to figure it out as well. im only gettin 9.7 volts to my pump. by the way, where is hte fuel pump relay??? i would really appreciate the help
