MikeyZee Posted March 9, 2010 Share Posted March 9, 2010 Hi All, My son and I are swapping a l28e from a 78 into his 72 240z. I have the wiring harness from the 78 as well as ECU, dropping resistor, fuel pump, fuel relay, ignition realy, and EFI relay. There is a 4 position plug downline from the ECU connection that plugs into the "umbilical" harness that I assume connects to the EFI, ignition, and fuel pump relay. Can someone let me know what else the "umbilical" is connected. Does it hook into the fuse block or any other relays? We have an outboard electronic ignition so we will not be using the factory 280z electronic ignition. I have looked through the 78 280z wiring diagrams but it seems not to cover that real well. Maybe I'm missing something. Since I don't have a 280 right here to look at it's a little tough getting my head around everything. I have a buddy that is donating me the wire harness because he's doing a SBC swap I just want to make sure I can get the harness and the relays out without causing him issues with his swap. Any diagrams or pictures would be helpful too! Thanks! Mike Quote Link to comment Share on other sites More sharing options...
T-Bone028 Posted March 9, 2010 Share Posted March 9, 2010 I'm sure you've thought about, and decided why you want to go with L28E with EFI, but maybe you can reconsider. For simplicity and less work (wouldnt you need new high-pressure fuel lines to handle EFI over the stock carb fuel lines?), why dont you swap the SU's onto the L28? Just a thought. I havent really considered all the necessities to swap to EFI or done any research so I may be talking out of my @ss. Quote Link to comment Share on other sites More sharing options...
MikeyZee Posted March 9, 2010 Author Share Posted March 9, 2010 We are going with EFI for drivability. We are at an altitude of about 6000 feet, going up the mountain passes can take you up to 10000 feet. We also frequently have up to 40 degree temperature swings in a days time. We do not want to sit there and adjust it once or twice a day. The SUs that were on there were junk and actually duct taped together and leaking fuel so they were swapped with old Weber DGVs early in the game. We picked up the L28e and most of the gear we needed and a 5 speed for $100 with the EFI as well as the ECU and harness. Now....that raises a new question though about the fuel lines. The hard lines won't hold the 40 psi or so put out by the 280z pump? I know the rubber hoses will need to be replaced. Thanks for the reply! Quote Link to comment Share on other sites More sharing options...
leftover z Posted March 9, 2010 Share Posted March 9, 2010 If you don't have the FSM, a link is in my sig line below. Quote Link to comment Share on other sites More sharing options...
MikeyZee Posted March 9, 2010 Author Share Posted March 9, 2010 I do have a copy of the FSM but it doesn't really give me an idea of how the harness is tied in. figure (EF-41) is helpful but I'm not sure how the harness is separated under the dash that goes out to the engine compartment or from the fuel pump relay, fuel pump control relay, and fuel injection relay. I could cut and splice and make a harness but I would rather pull what I need from my friends car leaving what he needs. Quote Link to comment Share on other sites More sharing options...
Geking Posted March 9, 2010 Share Posted March 9, 2010 (edited) If I am not mistaken, the 4 wires are: Switched power on (on at run and start) Tach signal fuel pump EDIT: fuel pump RELAY brake light (on a 280z, the brake light turns on when the motor stalls) - WRONG! It is crank 12+ EDIT: Looked and I can confirm I was wrong. On my 78 the brake light turns on from the blue wire coming out of the ALT, goes to a relay under the passenger seat. Also lights up the charge light in the amp meter. Edited March 12, 2010 by Geking Quote Link to comment Share on other sites More sharing options...
MikeyZee Posted March 9, 2010 Author Share Posted March 9, 2010 It looks like from the diagram the connections are for the ignition switched on, coil, ignition relay, and the fuel pump. Then they all seem to tie in to the connectors to the fuel pump control and fuel pump relays and fusible links even. I don't see the brake light connection. hmmm? Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted March 9, 2010 Administrators Share Posted March 9, 2010 Good thread with lots of detailed and highlighted pics/diagrams of the '78 EFI, including the umbilical, helping another with his '78 EFI. Start on this page linked below, post #54, scroll down and continue on through next few pages, should find what you need. I also attached a couple pics from that discussion. http://forums.hybridz.org/index.php?/topic/85452-i-got-a-fuel-injection-problem/page__st__40 '78 ONLY, umbilical and EFI relay. Hope this helps, Paul Quote Link to comment Share on other sites More sharing options...
MikeyZee Posted March 10, 2010 Author Share Posted March 10, 2010 Thanks for the info BRAAP. I studied that post before. That does help clarify some stuff. I am not 100% sure If I am going to use the factory fusible links. I may just put some circuit breakers in there. So, it looks like I will need to grab the harnesses that plug into the relays. I still don't know how that umbilical harness is tied in weather it's independent of the dash/gauge harness or if it is integrated. Anyone who knows let me know. Anyone know if the 240z hard fuel lines will handle the pressure from the 280z fuel pump. Any success or failure stories to share? The lines on there are in pretty good shape, the tank has been boiled out last year and is in great shape too. Thanks All! Quote Link to comment Share on other sites More sharing options...
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