Help needed with electrical problem

[R0162]

I posted a few days ago about the heat wrap falling off my exhaust and melting the insulation off some wires locally, we fixed the wires and the car was running fine.



but driving down the motorway the next day the fuel pump shut off, i straight away looked t the bank of 4 fuses and the normal one for the fuel pump had blown, i put in another and it blew again as soon as i turned on the ignition.
So i got the car towed and we stripped back the harness, it seem the wires linking to that fuse go to a block connector, we followed the route and it links to the ECU and the bulkhead relays, but the wires all look ok, we ran new wires for the fuel pump but left them disconnected,and we put new bulkhead relays.
It now seems that the fuse only blows when we connect the ECU and switch the ignition, immediately there is a crack as the fuse blows(20amp), but we opened up the ECU and there is no sign of a short or any damage.

At this stage i can pretty much say that all the wires look ok, all connectinms checked, It has to be shorting out somewhere to be blowing the fuse, but i am stumped as to what it could be or where to start looking, does anybody have any ideas what it could be or what to look at?

Thanks

Chris

[Blu3R]

Got a spare pump kicking around? If it's an old one you don't care about, hook it up electrically but don't bother plumbing it in and have another go.

[R0162]

we have not recnnected fuel pump at this stage, the fuse is blowing with pump taken out of the loop.

[GTO600]

Chris
I can't see it's your Ecu as it puts out a feed to the fuelpump relay which in turn swithces a feed via the fuse to your pump or aux relay if fitted.
Sounds like you have a shorting wire or incorrectly wired something, try dissconnecting the relay output cable then switching on the ignition you should then hear the relay energise & then go off after a few seconds, this will prove the Ecu circuit so then its down to wiring or aux relay if fitted.

[Blu3R]

R0162 said:

we have not recnnected fuel pump at this stage, the fuse is blowing with pump taken out of the loop.

So assuming you have upgraded your fuel pump wiring to incorporate a relay and have taken the supply directly from the battery/starter, fed to relay via new fuse and then on to your - now disconnected - fuel pump, what fuse are you saying is blowing? The original loom fuse or your newly installed fuse? I think I've misunderstood your post.

Edited by Blu3R on Friday 4th May 13:48

[R0162]

cheers for that advice Kevin i will try that.

Rob, the fuse blowing is on the bank of 4 above the battery, its the end fuse that is linked to the original fuel pump wiring.
It loops back to two other fuses on the same bank of 4, and then a wire goes to the connector block, which spur off in all directions, to the bulkhead relays, to the neg on the battery, to the ECU etc...

When testing to see if the fuse still blows, we have not yet connected the new wiring to the fuel pump into the main connector block, the fuel pump is completely isoltated frm the problem now occurring..

[dave sutton]

Have you checked the fuel pump relay? I had the same symptoms of that fuse blowing and it turned out the relay had blown to dead short. The relay is just to your left as you look down on the rear n/s wheel.