VP37 Pumpe baut nicht genug Druck auf ?! | Posts 16+

ulf wrote:

Bertil wrote: Although it sounds unlikely, it's still an idea: four jammed nozzles . Hi Bertil, Then, when loosening the screws on the injector side of the fuel lines and removing the injectors, shouldn't some diesel fuel leak out? It doesn't, according to the original post. Could all 4 relief valves instead get stuck

?

Hi Ulf,

That was just a utopian idea. I knew that it couldn't be the solution.

It's certainly as rare as winning the lottery to have all four nozzles simultaneously malfunction, or for all four relief valves to seize up, or for two pumps to get stuck near their zero position.

Quote:

The pump was also replaced again, but the new one has exactly the same problem.

"Does that mean..."
Was the pump replaced because the problem was already present?
Or did it occur after a pump replacement, and was the pump then replaced again?
Has anyone disassembled the pressure relief valves?

I would rather say that the control unit is not bringing the pump into the starting position (problems with the pump wiring - see Jörg's post). However, you should be able to hear this when turning on the ignition (self-test of the flow meter).

Hi!

First of all, thank you very much for the active participation and every tip; it at least helps to boost my morale. Great forum!

'All the electrical connections have been checked and are working correctly. We temporarily installed the control unit in another Golf 1Z for testing, and it ran without any issues except for the immobilizer.'
However, I haven't yet tried triggering the self-test. Wasn't it possible to do that somehow with a VAG-COM? Hmm... But those cables shouldn't just break like that... I'll check the continuity again.
Which one are you referring to? The 7 cables on the eight-pin connector?

The very first pump that was installed originally only caused the problem with the adjustment, which is why I wanted to replace it in the first place; at least it was still spraying something .

With the second pump, problems started: no fuel was reaching the injectors. I then thought the auxiliary fuel pump might be defective and replaced it, but now the third pump is exhibiting exactly the same issue as the second one.

And that two things have the same... Maybe I should play the lottery .

Bertil wrote:

I would rather say that the control unit is not bringing the pump into the starting position (problems in the pump wiring - see Jörg's post).

This should be audible when turning on the ignition (self-test of the metering unit).
Hi Bertil,

In cases like these, AFAIK, the yellow blinking light should come from the heating element }.
(If necessary, even with a delay – my AFN engine control unit takes about 30 seconds to report an error when the camshaft timing is incorrect.)

I will take a closer look at the error memory again. How should I sensorially perceive the regulations when I engage the ignition? The 'click' from the shut-off valve is normal, and I can also hear the turbo valve on the left side of the shock absorber. Should I listen for anything else? Should I put my hand on something?

Okay, here's the translation:

'It's fine that the issue might be related to a different part of the system. That's not entirely unexpected. However, it's unlikely that two pumps would have the same problem!'

'Please check all the connections to the pump! How did you test the system when the immobilizer was activated? How did you bleed the pump and the rest of the fuel injection system? And what about the tank ventilation? That could also be a possibility. Just bypassing the diesel filter isn't enough to indicate anything.'

What I also can't understand is the following: You disconnect the lines leading to the injectors on the pump. Diesel comes out. If you reconnect them and loosen them at the injectors, then no diesel comes out? Or have I misunderstood something?

ulf wrote:

...in such cases, the yellow blinking light should, as far as I know, come from the filament itself

.

My 1Z (also AF control unit) once stopped working due to a problem with the pump wiring "out of nowhere." The glow plugs weren't lighting up. I wiggled the connector on the pump, and it started working again – there was corrosion in the connector. That was good news, because the fuel quantity control system was constantly moving irregularly from stop to stop when the ignition was turned on.

So, if the error occurred after the pump replacement, then it could also be an installation issue.

Hi!

Okay, thanks again. I might try tackling this again soon and will let you know how it goes. Let's see what the snow is doing outside, and whether I have any heating oil (or a diesel canister) in the workshop to get the heating going... This thing has to work somehow... or at least, it should.

Regarding the issue with the nozzles or the supply line:

Here's the translation:

'No diesel is coming out either directly at the injectors or at the pump itself. However, if I remove this pressure relief spring, diesel does come out, which leads me to suspect that the pump isn't building up enough pressure to overcome the spring.'

I'll also double-check the wiring.

Thank you.

Okay, regarding the test of the engine control unit and the immobilizer:

The EWS (Engine Immobilizer System) behaves in a way that the engine runs for about 2 seconds normally, and then the EWS shuts it off. We tested this as well. When we connected the control unit and turned the ignition on, the engine started immediately but then shut off after approximately 2 seconds due to the EWS. This indicates that fuel is being pumped and other systems are working; otherwise, the engine wouldn't have even started initially.

I think that's what I'll do for now... Of course, I could also replace the control unit. But surely at least the glow plug filament should blink or the error memory should indicate something, right? Hmm... It shouldn't just break like that from a pump replacement.

Best regards,

The control unit is working correctly! I'll proceed with the other steps as described first.

Hi!

So, I've reviewed all the suggestions again just now, and I've come to the conclusion that it's probably the pump... there really can't be anything else wrong.

I got a gas can from the gas station, disconnected the inlet and outlet lines from the fuel filter and connected them to the can, it's running smoothly, the venting is working fine, then it starts doing the same thing again: fuel goes in through the inlet line into the pump and back out through the outlet line and back into the can... that's all.

The parking brake was reinstalled and checked; it is working properly.

Second person gets in the car, ear and hand near the pump, ignition turned, the pump hums happily and then clicks at the end, after which it falls silent; it seems that the control system is also performing a self-test and functioning correctly.

All cables between the pump and the motor control unit (including the fuse box) have been checked, and everything is fine.

Error codes read - nothing found.

It seems like the pump might be leaking internally. Is that even possible? Could it be that the return line is always open, preventing enough pressure from building up because the diesel is simply 'leaking back out' before any pressure can develop?

Okay... Tomorrow I'm going to take the car back to the junkyard with the broken pump. I'll show it to them and get a replacement, bringing one with me. Ideally, I should build one myself from a still-running engine, that way I can be absolutely sure it will work.

I will, of course, provide an update tomorrow.

Thank you again!

Okay, my crystal ball is showing me three possibilities:

- The pressure relief valve is defective. Forget about the clicking sound at the battery as a test. That doesn't say anything about its function under normal pressures (190 - 900 bar!).

- The pressure regulating valve/overflow restrictor is defective. It's usually integrated into the return screw. This indicates significant problems with adjusting the injection start. A minimum pressure must be present in the pump; otherwise, the high-pressure section cannot draw in diesel fuel. For the pump to start properly, there must be at least 1 bar of pressure inside during cranking. At idle, it should be around 4 bar. The injection timing adjuster is moved depending on this pressure. Even without electrical control, this creates a reaction based on engine speed. When adjusting the pump using basic settings, the electrical control is deactivated, so the position of the adjuster only depends on the internal pressure. Since your internal pressure is changing drastically, this could be an indication of a defective regulating valve (which is unfortunately located in the pump) or a clogged return restrictor/hose.

- The electrical system is faulty. You should never use static testing methods on cables in a vehicle. As soon as you start the engine or the motor is running, there are tremendous vibrations. Therefore, connect a continuity tester (one that actually works well, not a weak multimeter) at the beginning and end of the wire and then wiggle it every centimeter along its length...

Okay... and one more thing: while reading, I noticed that pump 1 has adjustment problems (as mentioned above), and pumps 2 and 3 are not functioning. If my memory serves me correctly, the first pumps had a control system with potentiometric feedback. This was later replaced by a contactless system using HDK. However, I don't have any documentation regarding material numbers, operating periods, etc., for these components.
Is it absolutely certain to rule out that as a cause of the error ?

CU Gremlin.

Gremlin wrote:

So, my crystal ball says: the check valve is defective. Forget about the clicking sound at the battery as a test. That doesn't tell you anything about how it functions under normal pressure (190 - 900 bar!).

... so, as a temporary measure, remove the shut-off valve, remove the valve piston (?), and then screw the shut-off valve back in. This used to work sometimes as a makeshift solution...

Quote:

If my understanding of the historical records is correct, the first pumps had a control panel with potentiometric feedback. This was then replaced wirelessly using HDK. I don't have any documentation regarding material numbers, operating period, etc. Is it absolutely certain to rule out this as a cause of the error

?
I suppose not, because if I remember correctly from the local postings, the shapes of the respective pump connectors don't match.

The issue with the pump's internal pressure could potentially be investigated using a "wooden hammer" approach: by slowly reducing the cross-section of a return pipe during operation, perhaps with a clamp or similar device.
If the increasing internal pressure eventually becomes sufficient, it should start up, or the pump should begin to deliver fluid with proper high pressure .

The diesel engine is running again.

After I had measured all the cables, replaced the control unit, and even started to doubt myself, the problem is finally solved. It turns out it was simply due to the pump head being axially misaligned... ugh...

I had pushed the pump all the way forward and backward myself at one point, but I unfortunately forgot that the head itself also plays a role in starting the pumping process.

'I unscrewed the pump head, it was pushed all the way to the left stop, I moved it to the right and screwed it back on, then started it. It started up as if nothing had happened...'

Grrr! / Ugh! / Grumble!

Despite everything, I would like to thank everyone for the helpful tips, tricks, and support in troubleshooting the issue!

Here's one last question: When adjusting the pump using VCDS, I have now set it to the blue line, but the measured values show, for example, during acceleration, 'Target: 12.0 degrees' and 'Actual: 10.5 degrees.' Should I now adjust the pump towards the red line?

Thank you.

Huh???

Blue line, red line???

Does that refer to the target band in the "TDI Graph"?

The middle (blue) line represents the target value.

http://www.ross-tech.com/vag-scope/cloud.png

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.

'Ei Logo,' I mean that's what it says on the logo itself, but as I already mentioned, it shows in the measurement blocks in VAG-COM, for example during acceleration, that the injection timing is incorrect, or shifted by 1.5 degrees. That's why I was wondering whether I should adjust the pump setting towards 'late' (red line) or 'early' (green line), since the setting with the blue line doesn't seem to be optimal.

Best regards,

My tractor also has similar deviations.

When stationary, it shows the blue line exactly as specified in the basic settings.

A log of the start of the boosting process during the flight is still missing.

Do you have a log file that contains the deviation?

Something else??? How did you get your head stuck on the ESP? Did it hurt?

Okay, please provide the German text you would like me to translate into English. I will only provide the translation.