Leaky diesel pump pressure sensor

[$hitblast]

It turns out the diesel pressure sensor on my diesel pump is leaking. The sensor sits in the middle of the four injector lines coming from the pump, and it's leaking several drops of diesel per second with the engine in operation. With two lines disconnected from the pump, it was possible to get at the sensor with a 17 mm open ended spanner.



The metal holding onto the plastic where the wires connect has several cracks around the rim. The wires, as you can see, are not insulated near the sensor, and they are even entwined. I wonder if it is supposed to be like this. Turns out it can be ordered from Germany for 551 USD. A bit expensive. Can I just put in a regular screw?

Edit: Part number 1467200303

Edit: Well, the twisting of the wires happened as my friend unscrewed the sensor, and likewise the de-insulation of the wires, so please disregard that info. Sorry about that.

[$hitblast]

Having browsed the Net for a few hours, it seems this plug isn't doing much, according to these threads:
aaz fuel pump wiring - The Brick-yard
AAZ injection pump wiring? - TDIClub Forums

It's tempting to stop the leak by blocking the mound of this thing with some epoxy. Knowing the cost of it, I'd ask you guys first.

[gldgti]

Yes, just block it somehow - or you should be able to fit a bolt withthe same thread and a copper washer - even better.

[$hitblast]

presumably SOLVED

Got it working again yesterday. After going through three auto-parts-stores, the junk yard and six hardware-stores, I found a matching bolt at the seventh. It was a little too long, but the right length with five washers added. I used three diesel-resistant plastic-washers, interleaved with two steel washers. The guy didn't have any aluminium or copper washers. It's a metric bolt, 8x1 mm. I had to tighten the bolt quite well, as there was at first a fine spray-mist leaking through.

It took a little less than a minute of churning to bleed the air out of the injector lines. I then tightened the nuts on the lines by the injectors, and churned for another minute, before it finally started and ran just fine. I drove it about ten kilometers in normal operation. I'm going to start it up again today, and see if it's easier to start than before.

[gldgti]

tip for easy priming (works EVERY time) - take off the fuel return hose and blow into down it to slightly pressurise the tank... its hard (like blowing up one of those party clow balloon things) but just blow until you see fuel going into the pump, then hold your finger over the end to keep the pressure in. Wait until some fuel comes out of the return outlet on the pump, and the just reconnect the hose. Should be only a few cranks until it fires up!

[$hitblast]

Thanks for the tip, Gld. I'll try it next time I have the chance.

My car is starting a little different than earlier after this fix. It used to only crank once or twice before starting in the summer; and this without glowing. Now it cranks about five times after glowing with three new plugs. I wonder if I could adjust this by screwing the new bolt somewhat more or less.

[gldgti]

it shouldnt make any difference at all - but the sensor probably controls what another solenoid on the pump does.

can you take a photo of your IP and post it so I can see which one you have?

[$hitblast]

Sure can.

[gldgti]

OK, so, there is an actuator in the bottom of the pump which controls flow of fuel from one side of the timing piston in the base of the pump to the other. You can see it in your 1st photo just left of the bottom end of the throttle lever damper.

Basically, for the pump to work like a pump without any sensors/actuators, you need to supply that actuator with 12V constantly with the key on. This will mean the timing advance and retard works just like on the old pumps - adjusts with pump pressure.

Now that you have defeated the pump pressure sensor in the pump head, that actuator may not be getting the right input - so if I were you I would cut the unplug it, figure out the polarity (its just a solenoid, you can hear it click on and off if you do some experimentation) and earth the correct side to the pump, and use the 12V that goes to the stop solenoid to power it.

Hope that makes sense!

[$hitblast]

Yea, is it the fuel metering system you mean? If it is maladjusted because of this, it would either give too low pressures at low revs, or too high pressures at high revs, I suppose. When starting up the car, then, the pressure would be too low, if the metering sleeve if left in a too leftward position, considering the schematic below.