Check VP37

Hello,

I replaced the fuel pump in my Audi 80 B4 with a 1Z engine with a used one. Since it's from a Golf or Audi A4, I had to replace the connector.

Now I have the problem that it's not working. Neither the fuel lines to the (removed) injectors nor the return line are dispensing diesel. I then held the fuel line directly into a glass filled with diesel. The pump also doesn't suck out a single milliliter of diesel from the glass.

I have already removed the ELAB piston, but that didn't help. I also tried unplugging the fuel pump connector completely, without any change.

Can anyone tell me if the problem could be due to the electronics, or does the pump definitely have to suck in diesel when the fuel pump connector is disconnected?
Thanks in advance!
mfg kaindl

The pump must suck, otherwise the following are the only options:
1. Wing of the pre-pump pump is clogged
2. Return flow control valve (RDV) on the return line is defective
3. Leak in the pump
There were also the first Audi 80 ESP models with Poti-MSW (part number 028130109J). This is not compatible with all other pumps.

Hello,

I checked this before, but I don't have the old type potentiometer (Poti) anymore, I have the new one...
I'm familiar with points 1 and 3, but I'm reading about point 2 for the first time. How can I check this?

I'll take a look tomorrow to see if I can find a vacuum pump to make sure everything is completely filled with diesel and try it again. If it still doesn't suck in without any connected electronics, then I can assume that the pump is defective.

Best regards,
Kaindl

Hello,
could you please provide the serial numbers of the original and the "new" pump? This might help someone determine if they are interchangeable.
Just to be sure, was the pump bled of air under vacuum?
Best regards,
Herbert

Solution for stuck impeller pump:

- "normal": insert an electric pre-feeding pump, start the motor.
- "rustic": spray brake cleaner into the suction port and start.

In both cases, the impellers usually disengage once the motor is started, as the centrifugal force at start-up is not sufficient to move the impellers outwards.

However, I only recommend the "rustic" method for experienced mechanics who have some experience with dosing brake cleaner: wink:

Hi,
Since the Audi 80 B4 1Z doesn't have a pre-feed pump, an extra one would need to be installed in the line before the fuel filter. Before starting any work, make sure the ESP (Electronic Pressure Regulator) is functioning correctly and that the system is properly bled.
After properly bleeding the system with vacuum (without excessive noise!!), you might let the fuel sit overnight, then possibly give the pump a few gentle taps with a plastic hammer while starting the engine.
I would be cautious about using brake cleaner in the fuel injection system, as it could dissolve any remaining lubrication (diesel). The dissolved material might then end up in other places.
The pump should not run dry, as this could cause further damage to the fuel metering system.
Best regards,
Herbert

Zitat:

Since the Audi 80 B4 1Z does not have a pre-feed pump, an extra one would need to be installed in the line before the fuel filter.

Yes, either electrically or with a diaphragm pump + assistant;

Zitat:

Before all the tinkering, it should first be certain that the ESP is correct and properly bled. After proper bleeding with vacuum (without gurgling!!)

I assumed that;

Zitat:

Maybe let the fuel sit overnight, then if necessary, give the fuel pump a few gentle taps with a plastic hammer while starting the engine.

You can save the "hocus pocus," as it's no more effective than simply putting your hands on it. The problem is that the fuel cells tend to stick when the engine starts at high RPM, especially if the pump has been sitting idle for a while. This is particularly noticeable with biodiesel engines, where even a 2-week period of the pump being fully submerged can prevent it from starting. Because the fuel is so hygroscopic, the fuel cells will essentially rust and stick together.

Zitat:

I would be cautious about using brake cleaner in the fuel injection system, as it may dissolve any existing residual lubrication (diesel). The dissolved material may then end up somewhere else. That's why I wrote that it should be sprayed into the intake air. Anyone who doesn't know this should generally avoid these "starting boosters".

Zitat:

The pump should not run dry, otherwise the wear and tear will develop the next damage in the volume control mechanism.

Before there's too much wear and tear, there's a Förderkolbenfresser;

@vwschrauber:
Let's assume the impeller of the fuel pump gets stuck, and would come loose when the engine runs at a higher speed. In order to start and then get the engine running, the high-pressure part needs to be supplied accordingly. To achieve this, you want to replace the missing flow of the impeller with an external pump. This pump should logically be located before the diesel filter, otherwise you might introduce dirt into the ESP.
- Hand-operated balloon pump: Very fluctuating, weak flow rate;
- Electric pre-feed pump - does it maintain the pressure in the filter and intake that is designed for suction/vacuum?

Brake cleaner or something similar in the intake air - there was already a negative outcome on this topic here. When starting, the glow plugs are on, and you get uncontrolled ignitions. The air mass meter (LMM) also gets excited.

I don't want to deny that you have already done this successfully - but how much of it was luck?
Best regards,
Herbert

Thank you for all the answers
I properly bled the system again today using a vacuum pump, and I re-checked the electrical connection, which seems to be okay.
Even after bleeding, the pump doesn't suck in fuel.

Given that the answers suggest that the glued-on impeller is the likely culprit, I'm hesitant to use brake cleaner and the plastic hammer method, so I was considering towing or having it towed. Ideally, this would allow the pump to reach operating speed, which might dislodge the impeller cells (possibly). Surely, nothing would be damaged in the process?

The check valve mentioned by slow-moe is located directly in the return pipe of the pump? Then I could try installing the one from the old pump.

I can't detect leaks in the pump without opening it, can I?

And if someone could confirm that the two pumps are identical except for the connector:
My original pump: 028 130 109L
The "new" pump: 028 130 110H

Best regards, kaindl

Zitat:

Logically, it must be before the diesel filter, otherwise you may be introducing dirt into the ESP.

Why? A pre-filter pump is always significantly more dangerous before the filter...

Zitat:

- hand-operated balloon pump: very fluctuating, weak flow rate;

It has also worked before - it was a temporary solution at the time, as I didn't have my tools with me, and I was very far from the workshop.

Zitat:

- Electric booster pump - does it maintain the pressure required for the filter and intake, even when operating under vacuum/negative pressure?

That's why I was referring to the filter. There are fuel filters that can have problems when installed, and the pressure difference of 1 bar is significantly exceeded.
He probably won't use a gear pump, as he probably doesn't have one :wink:

[quote]Brake cleaner or any other starting aid in the intake air - there was already a topic here with a negative outcome. During the starting process, the glow plugs are on, and you get uncontrolled ignitions.

Because everyone can't measure properly. You spray some, and then start the engine. Then the engine makes a short cough and shuts down. Then the intake system is completely filled with brake cleaner, and you can imagine what happens then :twisted:

The incandescent bulbs are off at room temperature with the TDI. Depending on the software version, the initial glow may be activated, but in that case you need to start for at least 3 seconds for them to heat up properly.

Zitat:

The LMM also benefits from this.

He has to endure it. All the more so because there are the same types of engines from LMM also for Otto engines (carbureted engines), and it's not uncommon for the combustion to back up into the intake tract. Why do you think you shouldn't, for example, run a carburetor engine without an air filter or with an open carburetor?

Zitat:

I'm not denying that you've done all of this successfully - but how much of it was luck?

I wouldn't attribute the fact that it has worked so far [b]to mere luck.

Zitat:

Even after venting, the pump doesn't draw fuel.

Definitely a wing-cell pump.

Zitat:

Given that the answers suggest that the glued fan pump is the likely culprit, I'm hesitant to use the brake cleaner and the plastic hammer method hasn't worked, I was considering towing or having it towed. Ideally, the pump would need to reach operating speed, which might dislodge the fan blades (possibly). It seems like nothing would definitely break?

This could work. Depending on the starting speed you achieve...

If it's properly bled and there's no dirt in the system, then nothing will break.

Zitat:

The backflow control valve mentioned by slow-moe is located directly in the inlet of the return pipe? Then I could test installing the one from the old pump.

This is the OUT screw. It's just a screw or a hollow pin with a 0.6mm hole.
You can remove it and blow through it if you're unsure whether it's clear. But I've never had any problems.
There's also the pressure relief valve on the opposite side of the inlet hole. It's usually sealed with yellow paint. It's a spring-loaded pressure relief valve that could potentially be open. But I've never had any problems.

Zitat:

I can probably not detect leaks in the pump without opening it.

If you have properly bled the air, then it can only draw air in through the shaft seal. All other seals are on the pressure side.

Okay, I just found out that the pump has been lying around since October 2008. That would explain why the rotor cells are stuck.

Unfortunately, I won't be able to pick up my Audi until tomorrow evening, so I'll try towing it and let you know if it helps.

Best regards,
Kaindl

Then it wouldn't be surprising...

Where are you from? If you're not too far away, I can help you get started: wink:

approx. 1 hour south of Munich... Kochel am See

Wow, that's quite a distance away;

But thanks for the offer!

Okay, I managed to get it running today by manually increasing the RPMs to 3000/min, but unfortunately, that didn't help. It's still not working properly.

I think that there's nothing more I can do without opening the pump.

Best regards,
Kaindl