AFN Springt nicht an | Posts 16+

AFNTDI1,9 wrote:

the solution has been found!!! I'm writing here about what caused the problem so that we can handle similar issues even better in the future. The relay or wiring to the diesel pump is broken, which is why not enough diesel is reaching the front. I've now built a temporary setup and connected 12V to the pump... now it's running

.
A VP 37 TDI with an electric diesel pump?
I'm not familiar with that at all.
I thought all the cars with the VP 37 fuel injection system were self-priming -> where is the pump located?

Or, more specifically, where did you run the 12V cable from and to?

Hmm... that's quite strange!

According to the wiring diagram, only the all-wheel drive model has a pump in the tank.

edit:

I just spoke with him. Apparently, a used fuel tank was recently installed! I suspect it's from a TDI PD engine (e.g., AJM). Those engines have a pre-lift pump. Of course, that pump isn't being activated because the power supply only reaches the contact point on the A-pillar. Only on PD engines is the corresponding relay and fuse 28 installed and wired. That's why the car only runs when he directly supplies power to the pump! That means either remove the pump and replace it with original parts, or rewire the pump using a relay and fuse. That should also work.

Regards,
Sure, here is the translation of the text from German to English:

"Micha"

Oh man...
I'm just imagining someone owning a used item and not knowing anything about it.

Best regards,
Robert.

edit:
Why a new tank, actually? Rust is not an option...?

Hello,

That just shows again how important it is to provide COMPLETE information about the vehicle.

@AFNTDI1,9:
I find it quite frustrating to expect help with such limited information. No one here has the time to waste on guessing games.

Best regards, Rainer.

Hello,
I also find it 'unfair' when someone doesn't reach out again after receiving advice that helped them.
Best regards,
Günther.

Hello,

I'm still working on the final solution...

According to the workshop, the installed tank is of the same design. I also spoke with them again, and since the engine ran without problems after the new tank was installed until it was empty, I didn't assume that the tank was the source of the problem.

Since I had this suspicion about the pump before, I asked in the previous threads whether anyone knew if it had a pump or not. (Perhaps I should have explained that.)

I'm sorry if I've offended anyone by excluding certain possibilities or making assumptions.

The fuel tank was replaced because of a crack. I don't know where the crack came from, but I suspect I drove over something that kicked up and hit it.

Okay, as I said, if I have the complete solution, I'll write down exactly what I did, if you're interested.


@Gühnter: There was never any mention that I would simply stop contacting you after that!


As I said, sorry again!


@MichaC. Will connecting the pump directly increase my power consumption, or could the filter or a pipe break if I do that?

AFNTDI1,9 wrote:

@MichaC. Will my consumption increase, or could the filter or a pipe break if I wire the pump incorrectly?

I also lack the experience to know for sure! I don't think anything will break. The fuel consumption shouldn't increase. Excess fuel flows back into the tank through the return line.

What's still strange is that it kept running until the tank was completely empty!

Hello,

I'm still working on the final solution...

According to the workshop, the installed tank is of the same design. I also spoke with them again, and since the engine ran without problems after the new tank was installed until it was empty, I didn't assume that the tank was the source of the problem.

Since I had this suspicion about the pump before, I asked in the previous threads whether anyone knew if it had a pump or not. (Perhaps I should have explained that.)

I'm sorry if I've offended anyone by excluding certain possibilities or making assumptions.

The fuel tank was replaced because of a crack. I don't know where the crack came from, but I suspect I drove over something that kicked up and hit it.

Okay, as I said, if I have the complete solution, I'll write down exactly what I did, if you're interested.


@Gühnter: There was never any mention that I would simply stop contacting you after that!


As I said, sorry again!


@MichaC. Will my consumption increase, or could the filter or a pipe break if I wire the pump incorrectly?

Hello AFNTDI1,9,
That wasn't meant to be personal.
My ARL Bora variant also has a fuel pre-pump in the tank; it turns on briefly when the engine is started, when the tank is about half-empty, presumably to bleed the fuel line.
Best regards,
Günther.

ARL is also a PD!

The front-wheel drive AFN engine in the Passat 3B definitely does not have a fuel pump in the tank.

Hello,

'What is this all about? The VP37 engines in these cars don't have a pre-injection pump, but the Caddy does. However, the pre-injection pump in the Caddy is very different from the ones used in PD engines. I'm concerned that the pre-injection pump will damage the ESP (Electronic Stability Program). Due to the pre-injection pressure, the shaft seal of the ESP drive shaft may be pushed out of its seat. The specified pressure is 0.2 bar above atmospheric pressure, but the pre-injection pump delivers significantly more. As a result, the injection pump is already drawing air through this shaft seal.' From my perspective, there should be no issues with the impeller pump being able to draw fluid through the pre-pump.

Hello,
The priming process also occurs in PD engines; furthermore, the pre-charge pump only runs for a few seconds when the tank is less than half full. It probably won't generate much pressure.
Best regards,
Günther.

Hello?

He's connecting the pump to a constant 12V power supply. It's constantly running and maintains a minimum pre-charge pressure of 0.6 bar.
And now, let's add one and one together...

Furthermore, you cannot compare the impeller pump of the VP37 with the tandem pump from the PD. So, always make sure to compare apples with apples, and not apples with pears!

Hello?!

He's connecting the pump to a constant 12V power supply. It's constantly running and maintains a minimum pre-charge pressure of 0.6 bar.
And now, let's add one and one together...

Furthermore, you cannot compare the impeller pump of the VP37 with the tandem pump from the PD. So, always make sure to pair apples with apples, and apples with pears!

Hello,
Sorry, I don't think what he's doing is okay either. I also don't believe that my pre-pump is designed for continuous operation.
I would have operated the pump using a button and only used it when the fuel filter is changed, etc.
Best regards,
Günther.

He actually doesn't need a VFP, period. Why then such convoluted constructions?!
Just as a VP37 TDI is not actually needed, it will not be needed in this case either.
However, in his case, it could be that the inlet and outlet are reversed somewhere, or more likely, that a check valve is installed, which prevents the fuel flow under certain circumstances. As I've mentioned before, the wing cell pump usually works without any problems when connected to the VFP.

Hello, so...

1. "Was this (defect) didn't arise intentionally or with a purpose, but is rather a manufacturing error from a workshop. By the way, the amount of cars in Immensen, Lehrte is amazing!"

"I only connected the pump to the constant positive terminal to get to work and back, which I know isn't very smart. But this morning, when I was leaving, I didn't even realize that the pump wasn't supposed to be connected there. I thought maybe a relay was broken."

3. I'm working feverishly on a solution to the problem, and ideally, I'd like to find a way to do it completely without a pump.

"@lappen "now youth-friendly "
What would you advise me to do? What is the most cost-effective solution?
Can I somehow remove the pump from the system?

If I suck on the fuel line with my mouth (VERY DISGUSTING), no diesel comes out...

What do you think about that?

I would try to find the original intake strainer that was installed in your tank. Theoretically, your workshop should still have the old tank, including that part. You could just replace it and that would be it. However, before doing that, I would make sure that the inlet and outlet lines are correctly connected to/from the tank, and that there is no check valve or anything else in the inlet line. If you absolutely need a vacuum pump, I would install a diaphragm pump (Hardi) or a piston pump (Facet). These are designed for continuous operation and are self-regulating (in terms of pressure). The generated inlet pressure of about 0.4 bar should still be okay and shouldn't necessarily force the shaft seal out of its seat. However, it's possible that it could. Problems with the pumping capacity (approximately 100 liters per hour) are occurring.