xxjoeyxxeb Posted March 31, 2009 Share Posted March 31, 2009 Alright, yesterday we had my newly swapped 83 l28et running in my 74 260z. Today we finally bled the brakes and went to start it, but no fuel. Listen for the fuel pump and nothing. Checking the blue/red wire the we connected that is supposed to have 12V for 5 seconds, then 0 V, but it is getting 5 V for 5 seconds THEN 12 V.... very weird. Also, when it is at 12V and connected to the wire that goes to the stock wiring relay for the fuel pump, it gets 0 V. Any ideas? Quote Link to comment Share on other sites More sharing options...
1rad280 Posted March 31, 2009 Share Posted March 31, 2009 Try sticking something in the flap on your mass air flow meter and retest see what happens. Quote Link to comment Share on other sites More sharing options...
HowlerMonkey Posted April 1, 2009 Share Posted April 1, 2009 Since he's getting the 2 or 3 second prime, I would assume he's using the L28et engine management system. If so, the ecu sends a negative out to a fuel pump relay on the blue with red stripe wire which you can find on a six way connector. After the prime/starter running/ the ecu won't send out the negative to energize the fuel pump relay until it sees a good crank angle sensor/distributor signal. The positive output from the fuel pump relay goes out also to the warm-up regulator on the green wire of the same relay. Depending on the year, some 280zx turbos use a fuel pump speed controller which is on the body harness rather than the efi harness. I believe it acts on the negative side providing a couple of levels of grounding resistence. You can probably go around it and might have already done so if the negative to your fuel pump is grounded to the body. Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted April 1, 2009 Author Share Posted April 1, 2009 Thanks guys, I should be able to loon into it further. As of now it is all 1983 Stocke ECU, harness, and Motor. I am still using a 280z with an External Voltage Regulator. The blue/red wire was getting the normal 5V for 5 seconds then turning off the other day when it started and ran fine, but I have no idea how it would switch to 5V then 12 V after 5 seconds over night without touching anything. There are 2 fuel pump relays on the 1974 carbbed 260z body harness and maybe the one we tapped into blew after it was running good.. Quote Link to comment Share on other sites More sharing options...
1rad280 Posted April 2, 2009 Share Posted April 2, 2009 Possibly, but I havent seen those go bad yet, Im not saying it isnt possible. Quote Link to comment Share on other sites More sharing options...
xxjoeyxxeb Posted April 2, 2009 Author Share Posted April 2, 2009 We got it running, but its running poopy. When we tried pulling the plug wires off some plugs, it didn't always make the car run worse so I might need to buy some plug wires, and maybe get the injectors flow tested. Quote Link to comment Share on other sites More sharing options...
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