Intermittent problem, engine kangarooing then stoping

Can anybody please point me in right right direction.
My 1995 300tdi 90 has a problem, I think it's a faulty white wire connection on the back of the ignition switch (that I think goes to the fuel pump). Can I run a live wire from the battery to the fuel pump to see if the fault is on the fuel pump circuit?

Just to clarify, you are talking about the solenoid on the injection pump, there isn't an electric pump on the 300tdi.

Run a live feed to the pump, then start it, see how it behaves now - pull lead off to stop. Solenoid could be shot too.

I didn't know what is on the back of the fuel pump, but I can see a white cable on the back of the pump. It comes loose and fell of once, I think the same is happening on the back of of the ignition. I just want to be sure this is where the problem is, plus I need to use Dora(the 90)

yep, thats the solenoid, to test just run a (fused) live to it, id be tempted to stick it into the cig lighter as an easy way of sorting it temporarily.
The wires on the ignition are all spade connectors, so id pull the dash front off, remove them one by one, give them a slight squeeze with some needle nosed pliers and put them back on to firm up the connection. (disconnect the battery first)

also, as a second though, check where to loom comes under the bulkhead, it may be chafed and damaged, mine was on the verge of when I did my clutch, so re-wrapped it at the time.

Do I wire it to the red cable on the back of the cigarette lighter?

id pop and get a cig lighter plug, plug it in to go somwhere, then unplug to stop the engine, was just a suggestion for an easy & usable temporary solution as, like me your landy is your main/only transport.
if it solves it, it needs the cable replacing properly back to the ignition switch.

Done, I've wired it to the interior light....well I thought I might as well use a switch.!!

Thanks for your help.