I am trying to sort my 1981 280ZX, when i received it, i wouldn't start or move. its an AT L28 non turbine.

I had to sort its differential, and stuff. I changed the plugs, fuel filter, cleaned injectors and all the fuel line and a brand new Nissan Fuel pump installad. still wasnt able to get fuel to the engine. I thought engine was bad but when i ran the fuel pump direct with the battery, the pump was running fine and can start the engine.

When i checked fuel pump wires voltage, it wasnt showing anything, like no power is received in them. I checked the 3 relays for fuel pump according to the hynes manual, and they are working fine (as per steps in Heynes manual).

i cannot trace the cables of fuel pump as they are 1. under carpet and 2. in the wire loop so difficult to extract.

what else could be causing no power to the fuel pump before i switch my cables to run directly from ignition switch to turn the pump always on? because running the pump directly on battery is giving too pump power and the car is giving out black smokes. I have for the moment put a electric fan meter to work as a resister to lower the voltage till i know how much power the pump is suppose to be supplied with.

 

Check your grounds. When I got my 79 I had to replace the negative battery cable, leaving the old one in I ran a new one from the battery to the starter. No lights, no cranking nothing, but everything when checked with my volt meter had 12v. When I took the old ground wire off I saw there was another spot where the cable was grounded to the frame, did it to the new one and everything worked.

 

i have checked the ground...i have good ground throughout the car...i can run the car if i directly wire the fuel pump with the battery directly...its only the fuel pump isnt running by itself...the wires of the fuel pump are the only ones that dont have any power...

 

Check and see if the idle air control valve is getting power when the fuel pump should be, they run off the exact same circuit. that also make the trip to find the bad wires shorter as well if its on that side.

I don't know if you checked it but is the connector under the deck mat in the hatch cleaned and connected?

 

The connector is clean and connected...that's where i have sourced my direct battery power to the pump so made sure of that first...

I will try to check the IACV for power...

sorry, in the middle east here and to USA there is time difference of 11 hours so i get my replies while you guys are asleep and vice versa

 

No problem.

Oh also are both the L connectors on the alternator and oil pressure sending unit connected? If their not the fuel pump wont run. And if just one is connected then it runs all the time sept for when the ignition is off.

 

Actually, i have not checked those connectors, or i know the locations of those connectors. L connector of alternator i assume you mean the L and S connector on the alternator.
Also the oil pressure sending unit i assume is the oil pressure sensor?

i will try to look at them today once i am home and post you guys. Thank you for the help!