Im stranded please help
Thread Starter
Junior Member
Joined: Nov 2017
Posts: 1
Im stranded please help
So My car wouldnt start & figure it was the starter so my mechanic made it start the old denso starter but we decided to change it becuase it would probably do the same thing again so we changed it and then it wouldnt start again so mechanic figure it would be the fuel pump and then he got into the fuel pump and out of nowhere there wasent any power going to the fuel pump and i''m sure the fuel pump is ok
what can i do make the fuel pump get power? I have 09 Scion tC
Or is there another problem?
what can i do make the fuel pump get power? I have 09 Scion tC
Or is there another problem?
Last edited by MR_LUV; Nov 6, 2017 at 07:05 PM. Reason: Moved to Correct Forum
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SL Member
Joined: Aug 2017
Posts: 68
The ONLY way your fuel pump gets power is if all the conditions for turning the motor over are satisfied. If the starter is turning the motor, but the pump has no power (WHILE the motor is cranking and attempting to start) then check the fuse/wiring/pump. Our systems do not prime like many other cars. This is a safety feature designed to shut the flow of gas in the event your motor stalls in a wreck to reduce explosion and fire risks.
Using the special diagnostics tool on the OBDII port to tell the ECU to cycle the pump for testing (listen for the sound) OR by cranking your car - which means you probably wont hear it. The dealerships really want you to use their special diagnostics tool that tricks the ECU into turning on the relay.
In order for the FP to operate, the EFI fues transfers power to the C/OPN relay (which is integrated into the fuse block lower left of the steering wheel) and while receiving CAS+ signals from the crank angle sensor allows the pump to turn on.
You can jump the pump directly with 12v, but dont do this for more than 10 seconds, and always connect/disconnect at the battery.
Under the hood, there is a EFI relay between two others that are the same. You can swap the efi and horn relay, check the efi (20amp) fuse, or use the diagnostics tool if you have access to it. Its possible that the CAS sensor or the c/opn block is flaky. The problem is that its the whole relay assembly and confuses the ____ out of everyone who tries to find the c/opn relay. You will find old pics of a grey c/opn, but thats on very old toyotas. Double check on your wires at that terminal block. Tell your mechanic to test the pump's connections on a 12v source and see if it runs. There is a pinout in the FSM.
I learned all of this recently trying to chase down a "faulty" fuel pump, which wasnt the issue - it was the rock poking through the block preventing it from cranking....lol.
Using the special diagnostics tool on the OBDII port to tell the ECU to cycle the pump for testing (listen for the sound) OR by cranking your car - which means you probably wont hear it. The dealerships really want you to use their special diagnostics tool that tricks the ECU into turning on the relay.
In order for the FP to operate, the EFI fues transfers power to the C/OPN relay (which is integrated into the fuse block lower left of the steering wheel) and while receiving CAS+ signals from the crank angle sensor allows the pump to turn on.
You can jump the pump directly with 12v, but dont do this for more than 10 seconds, and always connect/disconnect at the battery.
Under the hood, there is a EFI relay between two others that are the same. You can swap the efi and horn relay, check the efi (20amp) fuse, or use the diagnostics tool if you have access to it. Its possible that the CAS sensor or the c/opn block is flaky. The problem is that its the whole relay assembly and confuses the ____ out of everyone who tries to find the c/opn relay. You will find old pics of a grey c/opn, but thats on very old toyotas. Double check on your wires at that terminal block. Tell your mechanic to test the pump's connections on a 12v source and see if it runs. There is a pinout in the FSM.
I learned all of this recently trying to chase down a "faulty" fuel pump, which wasnt the issue - it was the rock poking through the block preventing it from cranking....lol.