Check VP37

Hello,
I replaced the fuel injection pump in my Audi 80 B4 with a used one. Since it came from a Golf or Audi A4, I had to replace the connector.
Now I have the problem that it's not being fueled. No diesel is coming out of either the (unscrewed) injectors or the return line. I then held the fuel supply line directly into a glass filled with diesel. The pump isn't even drawing a single milliliter of diesel out of the glass.
I've already removed the piston from the ELAB, but it didn't improve anything. I also tried disconnecting the pump connector completely, but that didn't change anything either.
Can anyone tell me if the problem could be related to the electronics, or whether the pump definitely needs to draw in diesel fuel when the pump connector is disconnected?
Sure, no problem!
Best regards, Kaindl.

The pump needs to be able to draw in liquid; otherwise, the only options are:
1. Impeller of the pre-feed pump is stuck.
2. Defective return flow control valve (RDV) on the return line.
3. Leakage in the pump.
The first Audi 80 ESP models were also equipped with a potentiometer-based MSW (part number 028130109J). This type is not compatible with any other pumps.

Hello,
I already checked that before, and I don't have the older Poti-ESP model, but the newer one.
I've heard of points 1 and 3 before, but I'm reading about point 2 for the first time. How can I verify this?

I'll check tomorrow if I can find a vacuum pump to make sure everything is completely full of diesel and try it again. If it still doesn't draw fuel even without any electronics connected, I can assume that the pump is defective, right?

Best regards, Kaindl.

Hello,
Please provide the model numbers of the original and the "new" pump. Perhaps someone can then provide more information regarding interchangeability.
Just to be sure, was the pump primed with a vacuum?
Best regards.
Herbert.

Troubleshooting a sticky impeller pump:

- "normal": Engage the electric pre-feed pump, then start the motor.
- "rustikal": Spray brake cleaner onto the intake manifold and start the engine.

In both cases, the impeller vanes typically detach as soon as the motor starts, because the centrifugal force at the starting speed is not sufficient to move the vanes outwards.

I would only recommend the rustic method to experienced mechanics who have some experience in dosing the brake cleaner .

Hi,
Since the Audi 80 B4 1Z does not have a pre-lift pump, one would need to be installed in the line before the fuel filter. Before doing any modifications, it's important to ensure that the ESP (electric fuel pump) is compatible and properly bled.
After properly bleeding the fuel system with vacuum (without using any bellows!!), let the fuel sit overnight. Then, if necessary, try giving the pump a few gentle taps with a plastic hammer while attempting to start the engine.
I would be cautious about using brake cleaner in the fuel injection system, as it may dissolve any residual lubrication (diesel fuel) that is present. This dissolved material could then end up in other places.
The pump should not be allowed to run dry, otherwise the wear particles will cause further damage to the flow control mechanism.
Best regards.
Herbert.

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da der Audi 80 B4 1Z keine Vorförderpumpe verbaut hat, müßte eine extra in die Leitung vor dem Kraftstoffilter eingebaut werden.

Yes, exactly - either an electric pump or a bicycle pump plus someone to help.

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Before starting any tinkering, it's important to ensure that the ESP

fits and is properly bled.
After proper degassing with vacuum (without using any valves!!)

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I assumed that.

den Kraftstoff vielleicht über Nacht einwirken lassen, dann ggf. ein paar leichte Schläge mit dem Kunststoffhammer auf die Pumpe während des Anlassens.

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You can skip the hocus pocus; it's about as effective as laying your hands on it. The problem is that the impeller vanes tend to stick when the pump has been sitting for a while, especially at the starting speed. This is particularly severe for those using biodiesel, where even a two-week standstill with a full pump can cause it to seize up and prevent the engine from starting. The material is so hygroscopic that the vanes literally rust and become stuck.

Mit Bremsenreiniger im Einspritzsystem wäre ich vorsichtig, da dieser eine ggf. vorhandene Restschmierung (Diesel) auflöst. Möglicherweise landet gelöstes Material dann auch wo anders.

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That's why I wrote that it should be sprayed into the intake air. Anyone who doesn't know that should generally avoid using such "starting accelerators."

Die Pumpe sollte nicht trockenlaufen, sonst entwickelt der Abrieb den nächsten Schaden im Mengenstellwerk. }

Before there's excessive wear and tear, it's experiencing a problem with its plunger.

@vwschrauber:
Let's assume the sliding vanes of the vane pump are stuck, and would come loose if the engine is running at a higher speed. To start the engine and then build up speed, the high-pressure side needs to be properly supplied. You want to replace the insufficient pumping capacity of the vane pump with an external pump. This pump must logically be placed before the diesel filter, otherwise you might pump dirt into the ESP (Electronic Stability Program).- Hand-operated balloon pump: Output varies greatly and is generally low.
- electric pre-feed pump - does it prevent the pressure from damaging the filter and the suction/vacuum system?
Using brake cleaner or any other type of starting fluid in the intake air – there was a similar issue discussed here before with a negative outcome. During the starting process, the glow plugs are activated, and you can get uncontrolled ignition. The mass airflow sensor (MAF) also doesn't like that.
I'm not denying that you've already achieved all of this successfully, but how much of it was luck?
Best regards.
Herbert.

Thank you for the many answers .
I bled the system again thoroughly today using a vacuum pump, and I re-checked the electrical connections, which seem to be correct.
Even after bleeding the system, the pump is not drawing any fuel.

Given that the general consensus seems to favor the glued-in impeller pump, and since I'm not confident in my ability to accurately dose the brake cleaner, and the "plastic hammer" method didn't work, I was thinking about trying to pull it out or let it roll out? In that case, the pump would need to reach a certain speed, which might loosen the impeller vanes (potentially). I don't think anything would break in the process, though.
The bypass throttle valve mentioned by slow-moe is located directly in the hollow bolt of the return line? If that's the case, I could try installing the one from the old pump there for testing purposes.

I suppose I can't determine any leaks *inside* the pump without opening it.

And if, hopefully, someone can 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.

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Die muß logischerweise vor dem Dieselfilter sein, sonst förderst Du ggf. Dreck in die ESP.

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

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- Hand-operated balloon pump: Pumping capacity varies greatly, weak;

It used to work sometimes - it was a makeshift solution back then because I didn't have my tools with me, and I was really far from the workshop.

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- elektrische Vorförderpumpe - hält das auf Saugen/Unterdruck ausgelegte Filter und der Vorlauf den Druck aus?

That's why I meant after the filter. There are fuel filters that can have problems if they are installed incorrectly, and the pressure difference can exceed 1 bar significantly.
He probably won't use a gear pump, as he likely doesn't have one.

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Brake cleaner or any kind of starting fluid in the intake air - there was already a topic about this here with a negative outcome. During the starting process, the glow plugs are on, and you get uncontrolled ignitions.

Because the idiots can't all measure properly. Sometimes they just spray and start. Then the engine makes a short sputter and dies. Then the intake manifold is completely filled with brake cleaner, and everyone can imagine what happens next .

The glow plugs in the TDI engine are off at room temperature. Depending on the software version, the pre-glow function may be activated, but in that case, you'll need to crank the engine for at least 3 seconds for them to warm up properly.

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Der LMM freut sich da auch.

He has to endure that. Partly because the same types of Lambda sensors (oxygen sensors) are also used in gasoline engines (naturally aspirated), and it's not uncommon for combustion to backfire into the intake manifold in those cases. Why else would you not drive a carbureted engine without an air filter, or with an open carburetor?

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Ich will ja nicht abstreiten, daß Du das alles schon mit Erfolg gemacht hast - aber wie viel war dabei Glück?

That it has always worked according to this pattern so far, I would not attribute solely to luck.

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Even after bleeding, the pump is not drawing any fuel.

Definitely a peristaltic pump.

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Nachdem aus den Antworten die allgemeine Meinung wohl für die verklebte Flügelpumpe spricht, ich mir die richtige Dosierung des Bremsenreinigers nicht zutraue und die Kunststoff-Hammer-Methode nicht gewirkt hat, dachte ich an anschleppen oder anrollen lassen? Dabei müsste die Pumpe ja auch auf Drehzahl kommen, so dass sich die Flügelzellen (evtl) lösen? Kaputt gehen dürfte dabei ja wohl nichts?

That might work, depending on the starting speed you can achieve.
If it's properly bled and there's no dirt in the system, then nothing will break.

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Das von slow-moe erwähnte Rückströmdrosselventil sitzt direkt in der Hohlschraube vom Rücklauf? Dann könnte ich da ja testweise die von der alten Pumpe einbauen.

This is the OUT screw. It's nothing more than a hollow screw or a hollow bolt with a 0.6mm bore.
You can expand it and blow through it to check if it's clear. I've never had that problem before, though.
Furthermore, there's the pressure relief valve, located on the opposite side of the inlet opening. It's usually sealed with yellow paint. It's a spring-loaded pressure relief valve that *could* be open. However, I've never encountered that situation.

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Undichtigkeiten IN der Pumpe kann ich wohl ohne die Pumpe zu öffnen nicht feststellen?

If you've properly bled the system, then the only place it could be drawing air is from the shaft seal. All the other seals are on the pressure side.

So, habe gerade eben erfahren, dass die Pumpe seit Oktober 2008 liegt. Damit wäre es nicht verwunderlich, wenn die Flügelzellen festkleben?
Unfortunately, I won't be able to see my Audi until tomorrow evening. Then I'll try towing it and let you know if it worked.

Best regards, Kaindl.

Then it wouldn't be surprising...

Where are you from? If it's not too far away, I can give you a ride .

Approximately one hour south of Munich... Kochel am See.

Oh, that's quite a distance away, actually.

But thank you for the offer!

Okay, so I tried running it at higher RPMs today, up to 3000 RPM, but unfortunately, it didn't help; it's still not pumping.
I think there's nothing more we can do without opening the pump?
Best regards, Kaindl.