[Mgs] Soliciting advice on an electrical problem

[PaulHunt73]

>From what you say you are largely on your own, except to say that you need 
12v at all the points shown on the standard wiring diagram for powering the 
pump, ignition warning light, ignition and starter.  If you have a standard 
harness it can't be that different from the factory diagrams.  If you have 
the warning light and it cranked you know the ignition switch itself is OK.

Next thing is the pump, and that is a matter of locating the white wire to 
the pump in the rear harness where the mass of connectors are in the engine 
compartment, and seeing if you have 12v there from a white in the main 
harness.  That should be in a 4-way bullet connector, two whites in the main 
harness, one is a supply wire from the ignition switch and the other goes on 
to the fusebox.

Once you have a pump, and it cranks, next thing is ignition.  Prior to 1973 
another white wire came off the ignition switch to the tach, through the 
pickup, and on to the coil +ve on another white.  So that is the next thing 
to trace through.  As a 66 the tach will have a third white wire to power 
its electronics, but that (and the accompanying earth) are not required to 
start the engine.

PaulH.


----- Original Message ----- 

> My project car, another 1966 MGB, is fully assembled. Today I was trying 
> to fire it up for the first time. But I knew I had an problem when the 
> fuel pump failed to start clicking when I switched on the key. First I 
> started troubleshooting the fuel pump,, but it soon became apparent that 
> there was a general lack of juice roughly everywhere downstream of the 
> starter. The alternator light came on, the starter cranked, but no lights 
> and no accessories. Unfortunately, it is a little more difficult to figure 
> this out than it should be, for several reasons:
>