The GTI I'm buying won't run

Hi,
I found an 1983 GTI that needs some attention. It has been sitting in a barn for probably 10 years and dust, rust and other issues have piled up. The price is OK though, and the seller is keen to make a deal. My biggest concern however, apart from the rust underneath, is that the 1,8 8v will not run. And when it doesn't run, it's hard to determine a couple of other things I would like to check.
The GTI has 189 000 km on the meter (equals appr. 115 000 miles). The engine turns on the starter, and if "start gas" is being applied, it fires up as long as start gas is present.
The seller suggests the fuel pump perhaps is the culprit, but I haven't has a chance to measure this. Neither have I any knowledge to what kind of petrol the fuel tank contains etc.
I suspect either the fuel pump, the injection pump, shitty fuel or some electrical malfunction to be the problem.
Any opinions, previous experience or suggestions from someone ? I'm considering towing the car to a VW workshop to have them check/change the fuel pump, and whatever other tricks the have in stock to bring this engine back to life. Are there any diagnostic tricks I can perform myself, before towing the car to the workshop?

If it has stood for 10 years then the petrol in the tank will be "dead" and it will not run on it.

More than likely the fuel filler neck behind the drivers side rear wheel will be rusty or worse. These particles will be in the tank and unfortunately now that you have tried to start it will be in the fuel lines. Water will also probably be present and if it has been pumped into the metering head and injectors it will of probably started corrosion inside them as well.

So start with the filler neck - if it is corroded then the tank will have to come out, fuel lines cleaned, possible metering head and injector replacement. There is a one way valve on the end of the pump, that maybe blocked as well.

If the filler neck is ok, then open the inspection plate under the back seat into the tank, have a look inside for rusty particles, get a magnet on a piece of string. If that is ok then it may just be the pump. You can disconnect the the fuel line at the metering head, bridge the fuel pump relay and see if you get fuel.

Buy a Haynes manual, all these procedures are explained in there.

if it runs when you apply throttle it cant be too bad, will probably just need a general spruce up and fresh fuel putting in. it may just be the octane rating is far too low and so the idle and co settings are too far out for it to run on the junk thats in the tank

tbh even if the engine is completely dead this is the easiest and cheapest bit to replace on a mk1, the bodywork etc are much more important when buying them.

a mk3 2.0 16v engien is a great upgrade, or even a mk2 1.8 16v for a light car such as this. or a 2.0 8v bottom end swap if you want to keep it more original

A non-runner is always going to be a lower price than a running car (even one without MoT etc and needing other work). A lot of the price difference is because of the "risk" of what it might need to get running. It could be a number of things. If it runs on easy start then the ignition side of it works, though, thus its fuel.

Since its 99.9% likely to be K-Jet then you ideally need to read up on this and get familiar with how it works, which will also answer why it doesn't work on this particular car.

I'm not sure what VW's hourly rate is, but I bet it would be a lot.

as has been said  body work is prob most expensive thing to sort out ,and mechanically you need to take car to old school injection mechanic who understand s this doesn't connect up to a laptop using its diagnostic port !The car is goin to be cheap with it being non runner and rusty.

Thx!
Sounds as if the engine may be salvable with some luck. The body is like I wrote, in pretty bad shape rustwise, especially from the doors and backwards. I have however found a complete Golf Mk1-body (not a GTI though) in good shape (missing all other parts than body itself). Would it be wise to swap all the parts from the GTI to the healthy body, including the numbers hammered into the chassis?
Or would it be easier to divide both cars in two parts, somewhere near the front window, and weld the healthy car's rear body to the GTI-front (since the GTI appears OK in the front)?
What are the major differences between GTIs and regular Mk1s? (I know some of them being the engine of course, the anti roll bars, the lowered suspension and dashboard/instruments/interior).

swapping chassis numbers would be illegal (over here at least, im sure it would be there too!)

there is nothing really different in the body shell from gti to non-gti, the only thing if the shell is 1.0-1.3 then the right side engine mount is in a different place, plus they have extra plates welded in at the bottom of the chassis legs. nothing that cant be sorted

everything else is just bolt on parts, so there would be no need to weld the gti front onto the non gti shell, unless the non-gti shell had front end damage