Custom wiring: Why does my land rover not start?

Hi all, I am back. Again, lol. This will be a bit of a longer read where there are multiple questions packaged into one.

Basic info:
109 74'
2,5NA (15J) no turbo
Std gearbox

I came back from holiday eager to drive the landrover again. However it did not start.
I checked the fuel pump, pumps fuel when cranking over. Heater plugs also worked like a charm. And which can be gathered from context: the engine cranks over just fine, nothing wrong with the starter.

Which already points me in the direction of:
- Its been 3 weeks so some stuff has corroded like hell
- A blown fuse

Otherwise, there really isnt much that can "break" all of a sudden.
However, that is where I get very confused and where my first sub-question arises: How can a diesel engine which does not need spark to fire; not fire when air and fuel are present in the cylinders and the engine cranks over beautifully? Petrol needs a spark, but diesel should fire up without this, right?

Anyways: (now disregarding fuel and air and going solely off of electricity) the thing is. My landrover is wired a bit differently, to the point where it has a safety type switch which must be flipped in order for the vehicle to start. I however do not understand how it works :/ (again ties into my subquestion, why does it need some form of electricity?)

If we take a look at the safety switch feature, all it does to my knowledge is from the fusebox short itsself to a part i cannot identify correctly. See picture.



the switch is a simple on off switch, which goes to the fusebox like this (fuse 1 blue wire)



what does this do? why does pulling a ground "work"?
Aside from this, judging from wiring schemes fuse 1 is all sorts of messed up, it should be all brown on one side and purple on the other. (tried this but to no avail).

So, update: magically it DID start. and ran well for about a kilometer, which is when i ended up stranded. Pulled everything apart on the side of the road. And put it back together. And just as magically it fired up. W H Y?! I dont understand what the blue wire does. And why it wont start without it.

Now it works again, but for how long. I dont mind finnicking on the side of the road. But i would like to understand WHAT im finnicking with.

All answers are greatly appreciated, thanks for taking the time to plough trough this long read.

Cheers

That looks like an injector pump stop solenoid, normally they need battery voltage to run, assuming yours is the same then it should be very easy to check.

lynall said:

That looks like an injector pump stop solenoid, normally they need battery voltage to run, assuming yours is the same then it should be very easy to check.

Click to expand...

Oh frick, that would make a lot of sense. Besides this explains why it may be messed up now, since it has been sitting there for 3 weeks covered in oil.

Thanks for this, i will check it out and report

ThomasLRNL said:

Oh frick, that would make a lot of sense. Besides this explains why it may be messed up now, since it has been sitting there for 3 weeks covered in oil.

Thanks for this, i will check it out and report

Click to expand...

A simple wire from the battery positive to the top of the solenoid will get you going, until you can sort it out properly.

lynall said:

A simple wire from the battery positive to the top of the solenoid will get you going, until you can sort it out properly.

Click to expand...

yup, the car runs again with the same setup as before. cleaned up all the contacts etc just for ease of mind.
Its more important to me that i understand now why and what causes it to shut off.

Thanks massively, weird this isnt showed in the diagrams i have. Are injection pumps aftermarket or something? Seems "vital" enough for it to be included in the wirings.

Anyways, thanks again!