Question about 1994 Toyota 4Runner
If the fuel pump operates with with a jumper at data link.That clears that the fuel pump is running.So check the EFI relay and the fuel pump relay. Now what is EFI relay:--- EFI Main Relay The EFI fuse supplies constant battery voltage to EFI main relay. The EFI main relay provides battery voltage to +B terminal of circuit opening relay (some models) and data link connector. Depending on model, EFI main relay may either be turned on directly by ignition switch or by M-REL terminal of Engine Control Module (ECM). The EFI main relay may also provide battery voltage to +B and +B1 terminals of ECM when ignition is turned on. The EFI main relay is located in engine compartment relay box. NOTE: Circuit opening relay is used on all models. Circuit Opening Relay Circuit opening relay controls fuel pump circuit. The Engine Control Module (ECM) receives an input signal at STA terminal when engine is cranking. Starter signal is also applied to STA terminal of circuit opening relay. Starter signal energizes circuit opening relay during cranking. Circuit opening relay then provides voltage to fuel pump or fuel pump relay.The circuit opening relay is grounded by ECM through FC terminal.Fuel Pump Relay & Fuel Pump Resistor .Fuel pump relay receives voltage from circuit opening relay and operates fuel pump. Fuel pump operating speed may be varied by Engine Control Module (ECM). When ECM grounds fuel pump relay, relay contacts close, and voltage is supplied through fuel pump resistor, to fuel pump. This changes fuel pump operating speed. ---------------------- As there are many other possibilities to check out of the mentioned procedure.But as you said fuel pump works with jumper wire and the fuel pump relay is replaced,on as per that i think the problem is the Fuel pump relay connections.The relay ground wire is connected to the ECM.If this wire is not connected properly or if this ground wire is got short or in-case not connected,then the ECM will not send signal to fuel pump relay to get started so it will not let the fuel pump start.But in jumper wire connection the relay is bypassed so no ground connection required and due to that fuel pump works. Thanks. Keep updated for any more query. You can rate this solution and show your appreciation
Posted on Sep 05, 2010
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Posted on Jan 02, 2017
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