Electrical question. Help please....

Heres one for anyone with any auto electrics knowledge as mine is fairly limited.
My series 3 has a v8 conversion and the electrics are all very thrown together by previous owners etc.
Now, I installed a new starter motor a few weeks ago, and a nearly new battery from a hilux I have, it started and run fine. Then it sat for a week.
Tried to start but was completely dead.
Not even any power to run the fuel pimp or fan ( these are both manually switched direct from battery)
Got the jump leads out and connected to my van,.....nothing
Visually checked all leads to starter, earth etc, couldn't see anything.
Checked fuses behind various switches and nothing had blown so I finally got my meter out to see if anything was getting past the switches and as soon as I touched the spade connector for the fuel pump switch with the probe the whole car sprung to life. Wierd!,
So any ideas why this happened?
Sorry for the long thread but wanted to give details..

Cheers

What setting did you have the meter on? If current you might have bypassed fuses?

Put meter on voltage and attach negative to a cleaned part of the chassis or engine block.

Test voltage of battery negative should be 0V
Test voltage of battery positive should be 12V
Ditto solenoid positive from battery
Try the horn - should sound with ignition off
Turn on lights redo all checks above
Turn on ignition redo all checks above
With ignition on test voltage AT EACH END of all fuses under steering column

Write down all the resullts and let us know results we can the start to track down problem. Sounds to me like something's not connected up right, a fuse has blown or ignition switch has fallen apart. The back fell of mine and had me scratching my head for a while...

Ok, so I just checked what you said and here are the results

Test voltage of battery negative should be 0V. Yes 0v
Test voltage of battery positive should be 12V. Yes 12v
Ditto solenoid positive from battery. 12v
Try the horn - should sound with ignition off. It does
Turn on lights redo all checks above. Same as before,
Turn on ignition redo all checks above. Same as before
With ignition on test voltage AT EACH END of all fuses under steering. All ok 12v

I had the meter on V when It first happened.

So when you say it's dead are all the ignition lights etc coming on on the dash when you turn on the ignition?

It was dead, I had no ignition lights, no horn, nothing, but when I touched the meter on the fuse connectors for the fuel pump which is independent and doesn't run through the ignition, everything came to life. Including the ignition.
It seems ok now, but Im concerned why it did it in the first place and if it's safe.

Mmm sounds odd, are the battery leads on nice and tight with clean connections? Is the connection to the solenoid from the battery secure and clean. I think that's the place to start looking as it is the single point for everything electrical and it sounds like it all went off at once. I'm guessing that the fuel pump is down near the starter solenoid, though could be anywhere on a conversion...

When fiddling with the solenoid connections DISCONNECT THE BATTERY earth lead. Always disconnect the earth first to avoid any nasty burns/fires/exploding batteries. If you disconnect positive first you risk slipping with the spanner and bridging to chassis...