Red Z Posted December 30, 2013 Share Posted December 30, 2013 I have a 1973 240 Z. My problem is I am not getting voltage to the fuel pump. I checked the fuse and it's ok. I'm getting voltage to the fuse load side and out, I'm getting ground reading from the neg. wire at the fuel pump. Any ideas or suggestions will be greatly appriciated.- Thanks! Quote Link to comment Share on other sites More sharing options...
winstonusmc Posted December 30, 2013 Share Posted December 30, 2013 With the pump running check the voltage across the wires feeding the pump. If its less than battery, then check from battery ground to pump plug positive, should be close to baytery. Then check from battery ground to pump plug negative, should be close to zero. You do this while the pump is running to make sure the wires and ground can handle the load. If these voltages are good, then the problem is elsewhere. Quote Link to comment Share on other sites More sharing options...
Red Z Posted December 30, 2013 Author Share Posted December 30, 2013 Always Here..Thanks for the response. I've tried doing that. I am getting zero voltage to the fuel pump. I checked the neg. wire (black) to the frame and I get continuity which tells me the ground is good. my positive line (green wire) is open somewhere Im assuming. Do you know if the positive wire is going through a relay?- Thanks Quote Link to comment Share on other sites More sharing options...
seattlejester Posted December 30, 2013 Share Posted December 30, 2013 Question, are you adding this fuel pump? Or was it always on the car? Quote Link to comment Share on other sites More sharing options...
winstonusmc Posted December 31, 2013 Share Posted December 31, 2013 Sounds like a break in the wire somewhere.There is a plug under the carpet in the trunk area, did you check there? Is the fuse in the plug by the fuse box? BTW, "Always here" is a status, not the Name, you kinda confused me in the response until I wasnt looking at this post on my phone. Quote Link to comment Share on other sites More sharing options...
Malarkey Posted December 31, 2013 Share Posted December 31, 2013 MOST 240 cars are mechanical pump cars. The 1973 240Z 1974 260z Fuel System Service Modification Plus service mod added the fuel pump to help with vapor lock issues. These cars run both a mechanical and an electric fuel pump. The modification also added a couple of relays, and a harness in the engine compartment and a harness under the dash. The harness in the engine compartment adds a wire to the starter solenoid connection, and the yellow(?) wire from the voltage regulator. Assuming that your car had this mod, Yes, there is a relay in the system, and You shouldn't get any voltage to the fuel pump unless the car is either cranking or running. Quote Link to comment Share on other sites More sharing options...
NewZed Posted December 31, 2013 Share Posted December 31, 2013 1973 BE-5 shows factory green wire with an inline fuse and no relay. Kudos to the OP for finding the fuse. You know you have power out of the fuse, follow the wire. Quote Link to comment Share on other sites More sharing options...
Red Z Posted January 2, 2014 Author Share Posted January 2, 2014 Happy New Year to all and thank you for your posts. yes it had a mechanical and electrical fuel pump. I replaced the the electric fuel pump with a Carter electric fuel pump and removed the Mechinical completely (Recommended by Carter). I will check the harness and the relay next this weekend. Quote Link to comment Share on other sites More sharing options...
Malarkey Posted January 5, 2014 Share Posted January 5, 2014 (edited) Sounds to me like a good plan to use the carter pump alone. NewZed is right about the in line fuse. (240Z's had provisions in the original harness for an electric pump, but they weren't used). If your car did have the mod (most all did), as a temporary solution you might be able to bypass it: Follow the green wire from the in line fuse, there is a T- connector with one green wire and one black with white stripe. Verify that this is the harness that goes to the relays that are on the right side of the passenger floor. You can remove the harness that goes to the relays and reconnect the wiring connection to the fuse holder the way the car was originally. If this works for you, keep in mind that your fuel pump will be on whenever the key is in the ON position- not ideal or safe. Edited January 7, 2014 by Malarkey Quote Link to comment Share on other sites More sharing options...
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