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1998 Jeep Wrangler 4.0 Fuel Pump Wont work. Replaced pump.

1998 Jeep Wrangler 4.0 Fuel...
1998 Jeep Wrangler 4.0 Fuel Pump Wont work.Replaced pump. By messing with the fuel pump relay Jumping it etc enough times i can get it to cough or even start for a second.Its a brand new fuel pump.
Not sure if the ASD is telling it not to pump. Im not super familiar with these systems.Im not new to auto mechanics and have no trouble codes in the PCM. I have a Snap-on Modis and im getting CKp signal when Cranking.with Key in Run ASD Relay is off as well as Fuel pump Relay
With key In start Fuel pump Relay and ASD both turn ON
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Answered in 15 minutes by:
6/12/2017
Amedee
Amedee, Jeep Technician
Category: Jeep
Satisfied Customers: 28,343
Experience: ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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Hello and welcome! My name is ***** ***** I can assist you with your question.
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There are several possible causes and several things to check to illuminate and or to start narrowing the root cause down.
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I would recommend to check for power going to the fuel pump while cranking the engine over. The computer should ground or activate the fuel pump relay for one second with the key turned on and then constantly as the engine is cranking over.
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If there is power to the fuel pump while cranking then check to ensure that the ground supply to the fuel pump connector is good.
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If there's no power to the fuel pump then we need to back up and check the inputs to the fuel pump relay. While cranking there should be two powers and one ground. Again the ground comes from the computer. There should be a main power supply going into the fuel pump relay and then a secondary power supply going into the fuel pump relay most likely from the ignition switch. If the fuel pump relay is not activating then we need to check the inputs. If the fuel pump relay is activating all cranking then we need to double check power back at the fuel pump or cranking.
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Customer reply replied 1 year ago
what pin would that be on the relay 86?
With Key off 86 is grounded or has no power. Key in Run it has power. 30 is power all the time.
Key in Run i have power also at 85 but it doesnt appear to be getting power tio 87
Give me a bit. I will pull a diagram for you and let you know. Driving now. Will be home in 20 minutes.
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Customer reply replied 1 year ago
ok
Customer reply replied 1 year ago
in the power distribution box the green/white is coming off 87. the harness to the pump has a green white im not sure if it goes through the PCM first however out of the Distribution box if I jump the 30-87 ive got 12 volts coming out of the GR/WH but at the pump I dont have enough power to get a voltage reading. but i can see enough power to light my led.

Sorry for the delay!

The red/light green wire going into the relay gets power with the key on.

The dark green/black wire going into the relay gets power all of the time.

The brown wire going into the relay is the ground from the PCM to activate the relay.

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Customer reply replied 1 year ago
ok found two issues one i may have casued installing the pump. The power to pump was broke 1/4 inch from plug.
second is no ground to the brown from PCM. If i jum from ground to brown Key OFF nothing happens key on pump will run forever but the vehicle operates.

Hello!

Would you be willing to speak on the phone?

Amedee
Amedee, Jeep Technician
Category: Jeep
Satisfied Customers: 28,343
Experience: ASE certified Technician advanced level specialist. Wisconsin certified emissions state inspector
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Customer reply replied 1 year ago
sure
Phone call session started
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