Chuma87

Hi friends..

I've been playing hardwiring for walbro 255 fuel pump, and at one point I unintentionally short-circuited, all for not disconnecting the battery...

MY car..
Forester S-Turbo MY02, no fuel controller module...only ECM

I left everything original, but it only started once, then it never turned on again..
All the fuses were checked. Only fuse SBF-5 from main fuse box was burned, But I solved it by soldering with tin, momentarily.
The problem is that the original fuel pump relay does not turn on, and consequently, the pump does not turn on.

The momentary solution, for the fuel pump to work, was to change that cable, for a GND coming from the chassis
Everything works, but the fuel pump never stop priming when key is ON (previous start)...Is annoying

I can even read and write to the ECM with romraider, and read codes with ecu explorer

I can find GND signal from B136 pin # 16 (Pay attention when the relay is connected, and when it is not)
B46 connector with relay unplugged.
-Searching GND signal from ECM.
Multimeter on continuity, black multimeter lead on chassis, red multimeter lead on ECM signal, key switched to ON...NOTHING
Multimeter on continuity, red multimeter lead on chassis, black multimeter lead on ECM signal, key switched to ON...2 seconds of "piiiiiiiiiii" from multimer = found GND signal from ECU.
-Searching V from ECM (low Voltage)
Multimeter on "20v", black multimeter lead on chassis, red multimeter lead on ECM signal, key switched to ON...4~4.5v found on that pin.

B46 connector with relay plugged.
-Searching GND signal from ECM.
Multimeter on continuity, black multimeter lead on chassis, red multimeter lead on ECM signal, key switched to ON...NOTHING
Multimeter on continuity, red multimeter lead on chassis, black multimeter lead on ECM signal, always "piiiiiiiiiiiiiiiiiiiiiiiiiiiii" (found GND) whitout switch key to ON.
-Searching V from ECM (low Voltage)
Multimeter on "20v", black multimeter lead on chassis, red multimeter lead on ECM signal, key switched to ON...12~12.2v found on that pin.

The mistake I had made so that the fuel pump relay did not work now (Pay attention to how I connected the original cables to the alternative relay (right A or B), knowing the original connection (left))

Is it possible that the GND is "weak" and that is why the 12v passes?

Don Clark

You seem to have forgotten the 12v ingnition feed also feeds the coils and has a further connection to the ECU. Probably the reason the pump continues to prime.....

As you appear to be from Cortines Argentina, have opted for the European LHD images.

Chuma87

That's because GND I get it from the chassis, and not from the ECM signal

Sure, it's LHD. I also have the manual

Chuma87

UPDATE:

A friend from the Subaru Argentina Club was helping me. I did the test with the ECM open, and I checked a MOSFET ... there is one that enables the GND signal ... it seems that it broke, since the positive signal reaches the gate (I suppose that what I measured was gate) of 5v during two seconds, with the key ON.



The mosfet is called GA 07 (it says that at the top). Does anyone know the replacement?