SImple advice needed about fuel pumps

I have a MK1 Golf GL with an injection later added. I think the guy that converted this didn't install the correct fuel pump as it doesnt build up enough pressure to start the car either hot or cold.
I have been told I need to replace the fuel pump (one on the chassis).. but Im finding it hard to find a pump for a MK1 Gti (which is I guess what I need now) - would a MK2 pump for a 1.8i be OK?
Much appreciated for any simple help here

mk1 gti had a pump and accumulater. later floppy tops had an in tank lift pump also. when you say, he didn't install the correct pump, which one did he use? the mk2 pump is different and sits in a different casing. it will work if you fit the whole casing and cradle, these also used a lift pump. if you look under the fuel tank inspection hatch (under the rear seat) you'll see if you have a lift pump or not.

also, how was the pressure tested? the pump may be giving good pressure but the metering head or wur may not.

I have spoken to a mechanic that is alot more clued up about this than me… he reckons I need a more powerful fuel pump to replace the existing (which has been tested by simply taking off the hosepipe and seeing the lack of pressure (wierdly though the car does drive fine… its only the startup thats a problem).

As the Bosch injector system has been added to the engine, I am told any car with this system.. an old Audi, Saab or Volvo will have compatible pumps..
and have been advised to get one that would be able to clout 5bar!
Do you think wooders a Bosch 044 fuelpump will help me here? Would it be easy to install to the Mk1 Golf?? And is all this making sense to you?
Thanks for your expertise on this…

oh and no there is no extra pump inside the fueltank

Do you have a GTI fuel tank (ie outlet on the side) or the old/previous/existing carb fuel tank?

Plenty of cars have compatible pumps but which differ slightly, and those slight differences might catch you out. Also you'll need an accumulator and the relevant hoses. Did they also upgrade the fuel send and return hoses, the GTI uses slightly wider ones? (ie how wide are your fuel lines)?

The easiest way to install it is to copy the GTI setup, ie use a fuel pump cradle, accumulator bracket and all the fittings from one. This might mean welding studs into the chassis/bodywork underneath.