20 Amp EFI Fuse blowing in 2007 Yaris

[SF1990]

I've had a 20 amp fuse blow which is in the EFI socket which is attached to the fuel pump, I've had the fuel pump replaced the first time and the car ran fine for about 5 months and then randomly out of the blue the fuse blew, I've had a brand new fuel pump installed and the fuse continues to blow. its had the fuel pump disconnected and the fuse still blows. At the moment the fuse seems to blow if the key is in the ignition, if you start the car fully there's no issue but if you just want to say open your windows the fuse blows. Anyone have any suggestion on what may be causing this problem? 

Its a 2007 Toyota Yaris 1 Litre 65 BHP 

cheers 

[flash22]

Start off by looking up the fuse list and see what that fuse covers

https://fuse-box.info/toyota/toyota-yaris-vitz-belta-xp90-2005-2013-fuses-and-relay

20A EFi - Multiport fuel injection system/sequential multiport fuel injection system

Now we can look at the wiring diagram

https://cardiagn.com/yaris-em00sce-ksp90-nlp90-nsp90-scp90-zsp90-wiring-diagrams/

Following the diagram that shows this 20a fuse is the power for the EFI relay, this supplies the COPN relay to the fuel pump

But it also sends power to the ...................

 

EGR (1kr engine)

MAF (1sz engine)

Fuel vent purge valve

AFR sensor (aka o2 sensor bank 1, sensor 1, Heater)

o2 sensor Bank 1, sensor 2, heater (post cat)

 

So that gives you some direction - If it was me i would start by unplugging the o2 sensor  bank 1, sensor 2 (may put a light on the dash) if it doesn't blow the fuse you know the issue - do not cheap out on o2 sensors Denso, NTK or Bosch if it's the actual issue

 

[SF1990]

Thank you very much for your reply I'll speak to the mechanic at my garage and see if he's checked out any of these sensors that might cause an issue.