Administrators BRAAP Posted December 4, 2009 Administrators Share Posted December 4, 2009 Follow Jeff's suggestion regarding the fusible link. (good catch Jeff, I totally missed the individual links.) The EFI main relay may be just fine as the injectors are getting power, but, the fusible link that is for the ECU power side of the relay may be blown, (fusible link is nothing more than fuse). It may have blown when the harness melted. This diagram that I highlighted should help show that little more clearly. As you can see in the pic below, when the EFI main relay energizes, it powers the injectors and the ECU. If the main relay is good, then pin #10 should be getting power when the injectors are getting power. You can use this diagram to verify the harness is correct as well, checking continuity from EFI relay plugs to ECU plug and umbilical plug. Also I was wrong again about your cold start operating correctly. If the engine is running for more than 5-10 seconds on the cold start injector then your cold start injector is getting power when it shouldn't be! Need to find out why! Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 4, 2009 Author Share Posted December 4, 2009 Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 4, 2009 Author Share Posted December 4, 2009 http://i183.photobucket.com/albums/x62/samuelzuniga/blue.jpg ok are you talking about these wires?? blue and yellow Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 4, 2009 Author Share Posted December 4, 2009 ok the fuseable links are ever soft wires like if they got hot before and melted a little , how do i fix that if there is a connector on them ?? Quote Link to comment Share on other sites More sharing options...
JSM Posted December 4, 2009 Share Posted December 4, 2009 Yes those two yellow wires. I think they are green going to the relay on the car though. Are you getting 12+ two both of them? Don't look at the condition, look for voltage to each wire to the EFI relay. Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 4, 2009 Author Share Posted December 4, 2009 ok will do Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 6, 2009 Administrators Share Posted December 6, 2009 How can I identify a 1978 ecu? I have two 1977 ecu and one 1978 Don't know if this helps in deciphering which of yours ECU's is '78 or not, but this ECU is for sure a '78 ECU. Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 6, 2009 Author Share Posted December 6, 2009 yes my fusable links on my positive battery side are bad , only oone works and the other is burned , maybe that is why im not getting power in pin #10 , how can i fix that ? , i forgot where is the link to fix those old fuses Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 7, 2009 Author Share Posted December 7, 2009 Hey Paul I got a question can you call me 321 356 0874 or text , thanks Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 7, 2009 Author Share Posted December 7, 2009 Ok today jsm came over and we did lots of test , we concluded that my ecu might be bad , is there any way to check if it's bad ? If not how can I convert a 1977 harness to work on my 1978 , remember the in dash plug on a 1978 is a fourplug and a 1977 is a five plug . Quote Link to comment Share on other sites More sharing options...
JSM Posted December 7, 2009 Share Posted December 7, 2009 Sammy, did you ever check the Ground Pins on the ECU plug before as Paul stated on Page 3? We didn't check that tonight. What we know as of now. One of the Fusible links was bad. Both were replaced tonight and Pin #10 had 12+ going to it. Still no go. We did verify that the switched power 12+ was going to the EFI relay, however it was not causing the new relay to switch. No power was going to the Resistor packs, but pin #10 was powered, complete opposite of before. We bypassed the EFI relay completely, verified 12+ to Pin #10, resistor packs, and ECU plug injector pins and on the ECU plugs themselves. Still no go. I'm assuming the tach jumping about 1/4" or so verifies that the signal is getting from the Distributor transistor and or to Pin #1 on the ECU. It looks like we verified everything in the EFI Bible and it says at this point to replace or try another ECU? One thing that is strange is now the car will not run at all on the cold start valve alone as it did before. Quote Link to comment Share on other sites More sharing options...
woldson Posted December 7, 2009 Share Posted December 7, 2009 So, I'm not as inclined to the level of trouble shooting that you guys are at here. However, something is in my gut is beginning to tell me that this is being over thought. Maybe take a break for 3 to 4 days and cogitate a bit. Let all the information simmer for a while. Sometimes you run into preignition at high rpm causing damage to the braino. Just my 2ct. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 7, 2009 Administrators Share Posted December 7, 2009 Ok today jsm came over and we did lots of test , we concluded that my ecu might be bad , is there any way to check if it's bad ? If not how can I convert a 1977 harness to work on my 1978 , remember the in dash plug on a 1978 is a fourplug and a 1977 is a five plug . You can replace the '78 harness and ECU with a '77 ECU-harness-EFI relay. Keep in mind, the '78 harness, ECU or relay will not work with the '77 so be sure you have '77 Harness, ECU and '77 relay for the '77 harness, (goes under the dash in the '77) With a few other things that recently came up, give me a day or so and I’ll line out exactly how to tie the ’77 harness into your ’78 car. Sammy, did you ever check the Ground Pins on the ECU plug before as Paul stated on Page 3? We didn't check that tonight. What we know as of now. One of the Fusible links was bad. Both were replaced tonight and Pin #10 had 12+ going to it. Still no go. We did verify that the switched power 12+ was going to the EFI relay, however it was not causing the new relay to switch. No power was going to the Resistor packs, but pin #10 was powered, complete opposite of before. We bypassed the EFI relay completely, verified 12+ to Pin #10, resistor packs, and ECU plug injector pins and on the ECU plugs themselves. Still no go. I'm assuming the tach jumping about 1/4" or so verifies that the signal is getting from the Distributor transistor and or to Pin #1 on the ECU. It looks like we verified everything in the EFI Bible and it says at this point to replace or try another ECU? One thing that is strange is now the car will not run at all on the cold start valve alone as it did before. Hmmm.... Sounds like everything was covered that could be covered, out side of verifying the rest of the harness is correct, i.e. pin-out are going to their proper destination. Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 7, 2009 Author Share Posted December 7, 2009 You can replace the '78 harness and ECU with a '77 ECU-harness-EFI relay. Keep in mind, the '78 harness, ECU or relay will not work with the '77 so be sure you have '77 Harness, ECU and '77 relay for the '77 harness, (goes under the dash in the '77) With a few other things that recently came up, give me a day or so and I’ll line out exactly how to tie the ’77 harness into your ’78 car. OK thanks Paul , I'm going to check my with my buddy 1978 280z if my ecu works on his car to determine if the one i got is bad Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 7, 2009 Author Share Posted December 7, 2009 So, I'm not as inclined to the level of trouble shooting that you guys are at here. However, something is in my gut is beginning to tell me that this is being over thought. Maybe take a break for 3 to 4 days and cogitate a bit. Let all the information simmer for a while. Sometimes you run into preignition at high rpm causing damage to the braino. Just my 2ct. yea i know but its hard when the car is your daily driver and you have been with out a car for 1 month now and parents nagging on it .. I even got threatened that the car was going to be sold Quote Link to comment Share on other sites More sharing options...
JSM Posted December 8, 2009 Share Posted December 8, 2009 yea i know but its hard when the car is your daily driver and you have been with out a car for 1 month now and parents nagging on it .. I even got threatened that the car was going to be sold I'll give you $400 for her, Sammy, just say when! You'll figure it out! Quote Link to comment Share on other sites More sharing options...
s!lvias30 Posted December 8, 2009 Author Share Posted December 8, 2009 Hahaha yea right Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 8, 2009 Administrators Share Posted December 8, 2009 Did you verify the following for your '78 harness; ...These pins should be earth ground; #5 #16 #17 #35 Be sure it is GOOD ground signal, i.e. no resistance! There will be a group of wire coming from the EFI harness into one eyelet that either attaches to the manifold itself or the fender well. Be sure that that ground connection is good. Also be sure the engine is grounded to the negative battery cable as well as the car body. Before I begin with the '77 ECU conversion, I want to let you know that with a Haynes manual you should be able to wire in a complete ’77 EFI system into your car. I have used the Haynes manual ’75-’77 EFI wring diagrams to install countless ’75, ’76 and ’77 EFI systems into 240’s Z that that were carbureted, and no one taught, told, or showed me anything about it, I had to figure it out my own, the hard way. I was pleasantly surprised by how easily it actually was. So everything I’m giving you is info you can figure out on your own with a little digging in the Haynes manual, which you should have. The '77 and '78 harness should have the wires individually numbered every few inches or so. Peel back the bundle sheath to reveal the numbers on the wires and they should match the diagram below. All the info I am providing here is based on that diagram below. With your ’77 ECU, ’77 EFI harness AND ’77 EFI relay in hand, here is the simple version of how to get it installed in your ’78 car. 1) This approach assumes the fuel pump is controlled separate of the ECU, (as it is in the ’78 car). As such, the wire for the Fuel pump in the ’77 umbilical and the '78 car umbilical is left open, connected to NOTHING, be sure it is protected well so it can not short out to ground in any way. 2) Connect the White/Red from the ’78 car umbilical to the ’77 EFI umbilical, Green #73. 3) Connect the Black/Yellow wire from the ’78 car umbilical to the ’77 EFI umbilical, Green #76. 4) Connect the White/Black wire from ’78 car umbilical to the ’77 EFI umbilical, Green #71. 5) (Leave the Green/Blue alone, connect it to nothing! Protect it so it can not short out against anything!) 6) Connect the Blue wire from the ’78 car umbilical to the ’77 EFI umbilical Black #1. The ’77 EFI has a separate +12v main power wire and separate – ground wire that connect directly to the battery. Be ABSOLUTELY sure you do not cross these wires when you connect them! They are both BLACK wires. a) #70 goes to the +/Positive side of the battery. b) #75 goes to the -/Negative side of the battery! 1) Plug in the EFI relay. 2) Plug in the dropping resistors near clutch master cylinder. 3) Connect all 6 injectors. 4) Connect the Water temp sensor. 5) Connect the AFM. 6) Connect the Air flow regulator. 7) Cold start injector and thermo-time switch are not necessary to have connected. So long as the fuel pump is operational, harness, ECU, and EFI relay are good, spark to the plugs, the engine should run. Hope that helps, Paul Sammy, For your '78 car, IGNORE the Fuel pump wire in this picture! Courtesy of Haynes Quote Link to comment Share on other sites More sharing options...
JSM Posted December 8, 2009 Share Posted December 8, 2009 Thanks Paul, I was looking for the Numbering on the 78 EFI umbilical for all the green wires. Did you get that off the Wiring schematic? In my quick search I didn't see it. Quote Link to comment Share on other sites More sharing options...
Administrators BRAAP Posted December 8, 2009 Administrators Share Posted December 8, 2009 Thanks Paul, I was looking for the Numbering on the 78 EFI umbilical for all the green wires. Did you get that off the Wiring schematic? In my quick search I didn't see it. Jeff, Is that what you are after? Got the exact numbers from another more legible '78 service manual. Quote Link to comment Share on other sites More sharing options...
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