Diesel Pre-Pump: Upgrade Options & Compatibility

Hello,
"I've been driving a Golf 3 TDI with an ARL engine swap for 2.5 years. What we forgot back then was to install the pre-injection pump and the diesel cooler from the donor vehicle. So, I've been driving around all this time WITHOUT these two components."
I want to retrofit this now; I already have the diesel cooler. I still need the pre-lift pump along with the fuel sender. The pump that was installed in the donor vehicle has the part number 1J0 919 050, but since that's not cheap, I wanted to try finding one on eBay. I found several there for VW, including one from a Passat with the 130 HP TDI (part number 3B0 919 050 B) and one from a Golf 4 V6 (part number 1J0 919 051 H). There were also some from the Golf 3 VR6 (which was a two-piece design) with 4 bar pressure, and one from a Polo SDI.
I'm now wondering which one I can use, as I don't want to spend the money on the original part. Do you know where the differences lie? Do they have different flow rates and pressures? Are there differences in the material (for gasoline and diesel engines)? I believe the installation diameter is the same for the Golf 3, Golf 4, and Passat, or do you have any other information?
It would be great if you had some tips.

Does anyone have any ideas?

Zak1976 wrote:

Does anyone have any ideas????

Probably not, pre-feed pumps haven't been a major focus area so far...

Hi Ulf,
Do you know where I can find information about the fuel pump? Even VW can't or won't help me. Otherwise, I'll just take the one from a Passat and, following the motto "what doesn't fit will be made to fit," I'll try to make it work. What surprises me is that the car is running despite the missing fuel pump and cooling. How is the actual fuel injection amount calculated? Isn't it measured directly in the high-pressure pump (PDE)?

Perhaps it doesn't really matter. In my old car, some people (before I got the car) installed a Pierburg fuel pump for 50 DM between the tank and the ESP, which started pumping even during the pre-glow phase. The reason was air in the fuel system, caused by a leaky diesel heater valve on top of the diesel filter. This air was pumped out before starting the engine. It's strange, I know .

I then removed the pump after it failed silently and the valve started leaking - everything is fine now. While researching what kind of pump it was, I discovered that BMW also uses this type - as a pre-pump.

What is the purpose of pre-feed pumps anyway? Since when is the rotor vane pump in the ESP no longer sufficient? With that information, we might be able to answer your question...

Um... No "Zak1976" wing cell pump is running PD...

"I think they are needed to ensure a consistent fuel supply. I also think they prevent air from entering the fuel lines. They may also relieve the pressure on the fuel injection pump. In any case, they save the battery if you happen to have an empty tank and want to start the car after refueling. A lot can go into an empty diesel filter... just turn the ignition on a few times, and then it should start without having to crank for minutes."
I'd like to know how the engine control unit (ECU) determines how much fuel is injected. I don't think it's measured directly anywhere, but if it is, where?
Is it really that important how much pressure the pump generates? As far as I know, there are fuel pumps for gasoline engines that produce 3 and 4 bar. Since my car is running, shouldn't any increase in fuel pressure improve the fuel supply? Or am I mistaken?