Weird electrical short - 15 AMP EFI FUSES BLOWING.. WITH NO ECU

[sw20r]

Hi everyone.. I've got the weirdest electrical short currently happening to a SW20 Body with no ECU plugged in.

The 15AMP EFI fuse now keeps blowing with no ecu plugged in. As soon as the key is engaged to "ON" it will blow. The funny thing I noticed is the Stock turbo Boost gauge is going all the way up.

This is the same case with all fuses removed todo with EFI, Relays + Dome. I have even removed the plugged from the map sensor and traced the wires going to "PIM" and nothing looks torn or to show visible signs of shortage..

Now with the ECU Plugged in it will start for either 10 seconds or 5 minutes then die. So there is no fault with the ECU if it can fire the injectors and ignition..

Could a short in the dash (Some of the Light bulbs are no longer working on the rev and speed counters) possibly cause the EFI circuit fuse to short?

Anybody got any thoughts or ever come across such a weird issue? This only happened on one of the rainy days last week in Sydney.. Car was turned off at BP then wouldn't turn back on again

[andrew_mx83]

a short in the fuel pump wiring can blow an efi fuse too as well as a shorted pump.

i found this out the hard way after about 60 efi fuses in my 'lux

[sw20r]

Fuel pump works fine. I did notice an intermittent short before when the car was running right.

At idle the power fc window would intermittently reset to the apexi logo. but putting the headlights on would cause the idle to stabilise from the rpm drop/power fc reset.

The MR2 OC in usa reckon -



If you have an open anywhere in the pressure sensor circuit, the gauge will read max boost. This is a redundanst FC safety. If there is a short or open in the pressure sensor circuit, the ECU puts 5 volts on the PIM terminal, so you will get FC whenever you try to boost.

it sounds like a short to 12v on the 5v sensor line.

the boost gauge signal is teed from the line going to the ecu. if its moving with no ecu plugged in to power the sensor, theres likely a short on the sensor power supply that is driving it.

so i'll give this a go later tonight