View Full Version : fuel injectors. any efi resistor? sw20 mr2 had fuel cut off?

07-25-2010, 06:55 AM
Hi. Sorry for the length but please hear me out, i'm stumped.

I have just put a gen 2 3sge into my st162 celica.

Its a jdm st162 with a jdm gen 2 3sge with a jdm 1990 sw20 mr2 ecu (3sge manual trans). I got spark but believe i have no fuel from the injectors. If i spray fuel into the intake manifold it fires up momentarily, fuel pump is working, fuel gushes from the fuel rail when i open it up so there is plenty of supply.

I was looking at the wiring diagrams, and thought it could be the absense of a 'efi resistor' (aka solenoid resistor) that could be causing issues. I didn't recall seeing one in my engine bay, so i looked at my old original loom AND THERE WAS NO PLUG FOR ANY EFI RESISTOR. Nor was there any efi resistor plug in the new loom from the st182 celica that the gen 2 3sge engine came off. This proved there was never originally a efi resistor used.

The Black & Orange wire supplying power to the injectors branches off and also powers the ignitor and coil etc with no efi resistor in line between the black and orange source and injectors. so if the engine was firing up initially, that means there was current going to the injectors as it was also firing up the ignitor and coil to spark etc in the circuit... which suggests that the injectors must of not been getting earthed by the ecu if they weren't functioning.

SO NEXT QUESTION. does the sw20 mr2 have a fuel cut off for security or does it have a 'clutch in' start routine or neutral start or something? (its a manual ecu though). Does the sw20 mr2 (1990) have a efi reistor? Is it unusual for my 3sge st162 (87' jdm) to not have one? it was a good runner prior to its death.

Any help appreciated and any thoughts as well. For the moment i'm going to go outside and take my multimeter and fish around...


07-25-2010, 07:06 AM
Just to help you out on what I know the Black with orange stripe is the Ground for the injectors. If there is a resistor plug on your harness it will have five Black with orange striped wires going to it.

07-25-2010, 09:15 AM
Update: I got 12 volts from each injector plug going to the ecu. thats been confirmed at the ecu plug.

Could a bad earth from e01 or e02 cause this?

Hi Rizin. Thats whats tripping me out mate, the original wiring loom to my jdm st162 did not have a 5 point plug. Nor did the original jdm st182 loom. So there was nuffin for any efi resistor that i am aware of.

SO the orange and black wire is the earth is it? woah! i thought it was otherwise. maybe this is my issue. SO the ecu supplies the current to the injectors rather than earth the injectors?

---------- Post added at 08:15 AM ---------- Previous post was at 07:29 AM ----------

I have just got another update from another forum although i haven't solved the issue yet.

Because its a 3sge the injectors are high impulse and therefore do not need resistors. they take 12volts directly, and the black and orange wire is the current supply with the ecu earthing when the injector is due to fire. hence why the original unmolested st162 and st182 loom did not have any 5 point plug for any resistors, as they weren't required for these models.

however 3sfe, and 3sgte have resistors on their injectors.

07-26-2010, 07:22 AM
I was totaly wrong on my last statement yes B/O is the supply and the ecu is the ground.