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I have been experiencing a problem with my fuel pump running. I put in a Nistune type 1 board into the ecu to tune my car, got it to run, but the fuel pump would cut out after running for about 30 seconds. It would prime the rail, but there would be no more fuel after running for 30 seconds. I replaced the fuel pump with a walbro 255lph, hoping it would fix the problem. Turned the key and the pump primed the fuel rail, good sign. But it ended up doing the exact same thing as the old pump. I took a look at the relays then and replaced both of the relays, still hasn't changed a thing. The Nistune software is giving a code in the consult gauge saying something like "ECU Fuel Pump circuit". I do remember when I moved into my new place I heard the fuel pump priming, but the keys were in my hands and the car was off. The objects in my trunk space were pressing on the wire connection from the fuel pump to the wires that lead to the ECU or relays (don't exactly know which). When I cleared the space I pressed down on the connector and was able to prime the fuel rail, haven't been able to do it since. Anyways, where should I start looking for wire problems? How do I find them?

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The ecu grounds the pump on 2 circuits, therefore it's perfectly possible your ecu has a blown main pump ground, probably because you upgraded pump...


The good news is, you have the priming circuit working, and it's a trivial matter to hook up an actual switch or switched relay to run the pump while driving.


If you haven't, you'll also need to upgrade the hot wire to the pump to something like 10ga, the walbro will have increased current requirements....

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The Flying Spaghetti Monster could probably help you out.  It will tell you what controls the relays that control the pump.  You'll need to know what kind of car you're driving.

Sorry, I am driving a 1987 Nissan 300zx Z31. I figured since it was in the Z31-300zx part of the forum I didn't need to specify.


Thanks G-E for the advice! I will try and fix what you said might be the problem!

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