Fuel injection pump, a unexpected problem.

I am in the process of converting two 1,9TD engines (from VW T4 vans) for a second life as boat engines, but encounter an electrical problem wiring the injection pump.
I once used a similar but much older engine for a power generator. The injection pump had a red wire hanging out that was connected to a solenoid. With 12 volts on it, the valve opened and the engine could be started.
But on these newer engines where I expected the fuel solenoid to be, there are two wires coming out, both with > 50K resistance to ground and/or each other. A solenoid should be 100 Ohms or less, so there must be something else in the black plastic box attached to the fuel pump.
According to the car's circuit diagram, the brown wire is connected to the ignition switch and the green one goes to the immobilizer unit that 'feels' the presence of the proper car key.

Can anybody tell me what signals must be applied to these leads to get the pump doing what it is there for? Just putting 12 V on them is not correct. The pump draws 15 mA for about a second, than falls back to about 5 mA. Both values are far to small to open a fuel valve.
On the other hand it cannot be very complicated because the rest of the engine it 100% mechanical.

 

Sounds like probably a digital logic circuit. It probably waits for a digital 'key' to tell it to turn on a solenoid. See if you can refit with the older style solenoid. Can you get the harnesses and keys that came with the engines?

Jimbo

 

To make tampering with the circuit a bit harder, they attached the device ("fuel valve controller" they call it) with 2 exotic screws that lost their heads in the fastening process, so you need a chisel to remove it. And not before the whole pump has been removed from the engine.
The engines were salvaged from damaged cars together with some other usable parts, the rest disappeared in a giant hydraulic press and will be reincarnated by now. What I will do if nobody with detailed knowledge comes forward is buy a new immobilizer unit and hook up to an oscilloscope to find out what the signal looks like.
As I said, except for this circuit the engine is purely mechanical. A can imagine a circuit that responds only to a digitized version of Germany's national anthem, but in this case it probably just will be a pulse of a certain length, a pulse train or even a fixed frequency.

 

Since it is a security device, it could be looking for a digital 'word' of a certain number of bits, keyed to that particular car. That is why I asked if you could still come up with the harnesses. Let's hope it doesn't work that way

 

CDK, eventually that box puts power on the fuel solenoid, right??

Once you grind off the screws and open the box, the solenoid coil contacts should be seen, I think... Trash the rest??

 

How does the repair shop phase and calibrate the pump? They must know.

 

You are quite right. There is no VW-Audi dealer on the island, so I put a friend at work who lives in "civilization". He just sent me a picture of an identical engine with the black box removed. Under the hood there is the solenoid waiting I've been looking for, with about 2" wire already attached. Problem solved!

For pump overhaul and adjustment there is an electronic box that simulates an immobilized that sniffs the proper key. For sale only within the dealer network of course.

Thanks for your contributions.

 

Attached is a picture of the innards I removed from the pump. It seems like is really needs a lot of digital code to enable the fuel valve. A 22-pins chip with lots of parts on both sides of the circuit board, quite a weird part for a mechanical injection pump. Once removed, the solenoid is freely accessible.

 

fuel pump

as you have described the fuel soleniod there are two on the pump. the one on the side of the pump has two cables coming out of it. do you know where these cables go. if you could help it would be appreacted. Regards Aaron.

 

What you have is a Bosch VE-EDC pump. It needs an ECU (electronic control unit) which belongs to a particular version of the TDI engine.
This thread was about the TD engine with a mechanical pump.