EFI Fuse Blowing

mudmaster · Feb 22, 2014

2000 4Runner, 3.4. As soon as the ignition key is turned it blows the 20A fuse under the hood. Anyone have any ideas what it may be?

It had a small fire 2 weeks ago that burned/melted some EVAP system vacuum hoses and some wiring. I just fixed/replaced all of that. It was starting and running fine prior to me fixing it, but was throwing a code for EVAP sensor.

skinny_pedal · Feb 22, 2014

Get a schematic. Start unplugging individual items in circuit until you don't pop the fuse. Then you can focus on that area.

dfowlkes · Feb 22, 2014

skinny_pedal said:
Get a schematic. Start unplugging individual items in circuit until you don't pop the fuse. Then you can focus on that area.

^^^this..lots of things it could be in efi circuit

mudmaster · Feb 22, 2014

dfowlkes said:
^^^this..lots of things it could be in efi circuit

Yeah. it's gotta be a bad ground somewhere. I'm guessing..........

Binder · Feb 22, 2014

mudmaster said:
Yeah. it's gotta be a bad ground somewhere. I'm guessing..........

Not likely a bad ground. More likely you didn't fix it so good after the fire.

WA-Wheeler · Feb 22, 2014

Binder said:
Not likely a bad ground. More likely you didn't fix it so good after the fire.

Yep. X2

zukkev · Feb 22, 2014

mudmaster said:
Yeah. it's gotta be a bad ground somewhere. I'm guessing..........

Does it instantly blow it as soon as the key is switched on? A bad ground will not blow a fuse (a poor ground may eventually cause excess heat at a connection and melt something, but it won't blow a fuse)...a SHORT to ground will. I'm betting there's a damaged sensor somewhere in the Evap sensor circuit, possibly caused by the fire. Or like was said before, the repair was not so good...

mudmaster · Feb 23, 2014

zukkev said:
Does it instantly blow it as soon as the key is switched on? A bad ground will not blow a fuse (a poor ground may eventually cause excess heat at a connection and melt something, but it won't blow a fuse)...a SHORT to ground will. I'm betting there's a damaged sensor somewhere in the Evap sensor circuit, possibly caused by the fire. Or like was said before, the repair was not so good...

Not exactly, it blows once the key is turned to start. There is a sensor that had a melted connector on the wiring side. This connector and the wiring were replaced. I did find another sensor in the system, but haven't checked it out yet.

zukkev · Feb 23, 2014

mudmaster said:
This is exactly what it's doing. There is a sensor that had a melted connector on the wiring side. This connector and the wiring were replaced. I did find another sensor in the system, but haven't checked it out yet.

Did you replace the sensor too? I bet the sensor is what caused the original melting...Shorted to gnd...