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Got an 87 Nissan d21 w/ vg30i engine. I've replaced the fuel pump, but I'm not getting power to the pump. i can jump the relay and the pump comes on. I've got 4 wires coming into the relay two black w/white strip, one white wire w/ blue strip, and one white wire w/ red strip. got power to the two black w/ white strips but nothing to the other two witch i assume are for the fuel pump the white w/ blue i know goes to the fuel pump and the white w/ red goes to the computer. then when i do jump the fuel pump and start the motor it will start and then dies. feather the gas pedal and it will stay running, runs like crap but runs. give you a run down on what I've done, I've pulled the motor had it rebuild put motor back in. i have removed all the EGR stuff and the air injection system and the fuel mixture heater. Any help would be great!!!!!!!
 

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NF Mod/Nissan Master Tech
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Your fuel pump relay has two side: the "switch side" which, when closed, sends the power coming in from the white/black wire to the white/blue wire, which goes to the fuel pump (the fuel pump has a black wire, which goes to chassis ground). Since you jumped the switch side of the relay and the fuel pump ran according to you, then we know that the circuit to the fuel pump from the relay harness connector is good. BTW, have you tried substituting another relay to make sure the fuel pump relay is good?...
The other side of the relay is the "solenoid side." When the solenoid inside the relay is energized, it acts like an electromagnet and pulls the switch side circuit closed. The solenoid side receives its power from the white/black wire (FYI, both white black wires splice together into a single wire before it gets to the relay and go to a 10A fuel pump fuse). The white/red wire is the circuit between the solenoid and pin # 108 of the ECM. The ECM has an internal driver that grounds the circuit, which, in turn, causes the solenoid to energize, pulling the switch side closed and allows power to be sent to the fuel pump. If the fuel pump is good and it has a good ground, the fuel pump will run. There is also a prime mode when the key is turned "on," the ECM will activate the fuel pump relay and allow to the pump to operate for several seconds to prime the system and then it will shut the relay off until the engine is cranked or the ignition switch is reset to "off" and then "on".
It's possible to have a bad driver inside the ECM, but being that you state it runs like garbage when you do jump the pump, I'm thinking there is a bad ground connection somewhere which is not only affecting the fuel pump operation, but one or more other engine control components. I know there are two EGI ground points on the intake plenum on the VG30E and VG33E engines, but it's been a long time since I worked on a VG30i and I can't remember if there is a grounding point on that particular intake or not. I would take a careful look at the wiring around the engine to see if there is one or more ground wires that are not connected OR do not have a clean connection. Otherwise, you will have to get an ECM pinout diagram (check the factory service manual) and wiring diagram ( | Repair Guides | Wiring Diagrams | Wiring Diagrams | AutoZone.com ) and check all of the ECM grounds for continuity and minimal resistance. Specifically, you'll want to check ECM grounds at pins # 105 , 106 (black wires) and # 107 , 109, 112 and 113 (black/red wires).
 
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