Kangoo dTi purchased: What now? / Possible issue with fuel tank vent.

Hello,

Yesterday, I had the Kangoo with a loss of power (see: significant loss of power, specifically...). I bought a Kangoo 1.9 dTi, as discussed in this forum.
Renault and Bosch together cover almost everything in the field of fuel injection systems, including... ESP) and the diesel fuel supply system were replaced or checked, and we looked into what options were available.
The turbocharger appears to be okay. Last pressure test performed, error codes read, diesel fuel drained, filter replaced, fuel lines blown clean... on April 4, 2002. The ESP system was also replaced here.
Everything without any noticeable effect—no change in performance.

The owner was at a loss and that's why he's selling the car! And now, me?!
Yesterday, I opened the fuel cap, and I heard a hissing sound.
I mean, a hissing sound caused by a vacuum!

'In the Kangoo forum, some people said that this isn't just a Kangoo problem, but occurs in many vehicles. I don't have an explanation for it, but the ESP should be working harder under low pressure!' But this simple explanation for the performance loss would also be far too simplistic as a cause.

How is this vacuum created?
Okay..., and if you have any other tips (regarding engine power), I'd be grateful for any suggestions.

Best regards, Klaus.

... if the fuel tank vent is defective, the fuel injection pump will have increasing difficulty drawing enough fuel due to the increasing vacuum inside the tank.
Just try driving it without the fuel cap; if you have a tank cover and the tank isn't completely full, it shouldn't be a problem.
It's possible that corners were cut during the fuel tank modification, and who knows what other lines and switching valves might be present in the fuel lines connecting the tank to the ESP (Exhaust Gas Recirculation) system.
A new diesel filter should be a must-have if you haven't already replaced it (I'm not sure anymore, so don't create a new post every time, just reply to the old ones. That way, you can see the history at a glance, and posts that have been replied to will automatically move back to the top).
Let's check if the problem might be here:
- Disconnect the line between the diesel filter and the ESP (Exhaust Gas Recirculation) system.
- Close the ESP inlet to prevent air from being drawn into the pump during the test.
- either use a long (2m!) hose to siphon from the diesel filter, or use a vacuum pump (diesel tastes bad and is unhealthy ).
- Assess the suction performance; if nothing or very little is coming out, you likely have a blockage.
- No air should enter.

I just remembered something: I suspect your car has a standard distributor injection pump that is electronically controlled, right? If a pre-feed pump was installed in the tank or after it as part of the tank modification, then it needs to be removed.
Because if it's not connected now, it acts as a nice throttle valve. If it is connected, make sure the pressure in the ESP (Electric Submersible Pump) doesn't get too high, otherwise the shaft seal of the ESP will eventually be pushed out.

Best regards, Rainer.