Won't start after new vacuum pump

G

Gunnel

New Member
Hi all.

When I bought my A2 1.2 diesel six months ago the owner told me he had had problems with the car going into limp mode. After a while it got harder and harder to start. It would always start when the nose pointed downwards but upwards on my driveway was a struggle. I started to hear a whining noise from the back and concluded that it was the in-tank fuel pump. Changed that. Car was a little bit happier but still making the whining noise and sometimes hard to start. Changed the fuel filter just to be sure. Car got still a little bit happier but the problem remained. Last week I changed the vacuum pump situated to the left(while sitting in front of the wheel) of the engine. Since there is no primer I had to crank it to start it which took me 8 tries + battery charging + 6 more tries. Took it out for a 20 minute drive, no whining noise and it was happy and quicker in it's response. Heureka! The day after I went to the store, it started immediately and everything seemed fine. It's a 5 minute drive. When I tried to start it in the parking lot it didn't work. Almost wore out the battery before I got it to start. Went for a drive but it didn't respond well, shaky as soon as I wasn't accelerating. After that it was impossible to start. It ignites once at best but then immediately dies.

I didn't have a torque wrench for the new vacuum pump, borrowed one today and was able to check the top two bolts. They had to be tighten a little bit extra but they didn't seem lose at all so I don't believe that's it. Will try and find a torque wrench that goes down to 10 tomorrow to check the two bottom bolts but they are not loose at all. Checked the three hoses. The top two are firmly fastened. The one on the bottom is possible to wiggle a little bit but still kind of tight.

If there is anyone that can offer any insights or ideas I would be most grateful. I also hope I'm posting in the right forum, otherwise just let me know.
 
Take a picture of the tandem pump and mark the loose one. Carefully check all your fuel pipes for deterioration as this can cause them to become porous and let in air.
1606668996014.png

Port 1 is the fuel feed.
port 2 is the fuel return.
Port 3 is the vacuum "supply".
All connections need to be very good to prevent air entering.
 
Gunnel said:
Hi all.

Last week I changed the vacuum pump situated to the left(while sitting in front of the wheel) of the engine. Since there is no primer I had to crank it to start it which took me 8 tries + battery charging + 6 more tries. Took it out for a 20 minute drive, no whining noise and it was happy and quicker in it's response. Heureka!
Click to expand...
No, you do not have to crank - I will definitively recommend to use vacuum to vent fuelsystem.

Diesel is a liquid with poor capabilities as lubricator.
When you crank for a long period you wear several of the components it the fuelsystem.
Use vacuum.

Cheers
dieselfan
 
Last edited:
Gunnel said:
Hi all.

When I bought my A2 1.2 diesel six months ago the owner told me he had had problems with the car going into limp mode. After a while it got harder and harder to start. It would always start when the nose pointed downwards but upwards on my driveway was a struggle. I started to hear a whining noise from the back and concluded that it was the in-tank fuel pump. Changed that. Car was a little bit happier but still making the whining noise and sometimes hard to start. Changed the fuel filter just to be sure. Car got still a little bit happier but the problem remained. Last week I changed the vacuum pump situated to the left(while sitting in front of the wheel) of the engine. Since there is no primer I had to crank it to start it which took me 8 tries + battery charging + 6 more tries. Took it out for a 20 minute drive, no whining noise and it was happy and quicker in it's response. Heureka! The day after I went to the store, it started immediately and everything seemed fine. It's a 5 minute drive. When I tried to start it in the parking lot it didn't work. Almost wore out the battery before I got it to start. Went for a drive but it didn't respond well, shaky as soon as I wasn't accelerating. After that it was impossible to start. It ignites once at best but then immediately dies.

I didn't have a torque wrench for the new vacuum pump, borrowed one today and was able to check the top two bolts. They had to be tighten a little bit extra but they didn't seem lose at all so I don't believe that's it. Will try and find a torque wrench that goes down to 10 tomorrow to check the two bottom bolts but they are not loose at all. Checked the three hoses. The top two are firmly fastened. The one on the bottom is possible to wiggle a little bit but still kind of tight.

If there is anyone that can offer any insights or ideas I would be most grateful. I also hope I'm posting in the right forum, otherwise just let me know.
Click to expand...
Hi Gunnel,
It is advised to prime the pump by fitting a hand held vacuum pump to the output side of the pump this ensures that the fuel is all the way through the pump with no trapped air, should then start a lot easier.
Hth
Keith
 
audifan said:
Take a picture of the tandem pump and mark the loose one. Carefully check all your fuel pipes for deterioration as this can cause them to become porous and let in air.
View attachment 73656
Port 1 is the fuel feed.
port 2 is the fuel return.
Port 3 is the vacuum "supply".
All connections need to be very good to prevent air entering.
Click to expand...
It's the fuel return, nr 2, that is a little bit loose, hardly loose at all. I'll have a second look at it though, thanks!
 
dieselfan said:
No, you do not have to crank - I will definitively recommend to use vacuum to vent fuelsystem.

Diesel is a liquid with poor capabilities as lubricator.
When you crank for a long period you wear several of the components it the fuelsystem.
Use vacuum.

Cheers
dieselfan
Click to expand...
OK, it didn't feel right to crank it like that. Thanks.
 
kp 115 said:
Hi Gunnel,
It is advised to prime the pump by fitting a hand held vacuum pump to the output side of the pump this ensures that the fuel is all the way through the pump with no trapped air, should then start a lot easier.
Hth
Keith
Click to expand...
By output I'm guessing you mean the fuel return hose?
 
Recheck all the rubber fuel hoses around the tank, fuel filter and tandem inlet. you have disturbed several areas any can leak air.
 
Just curious. The 1.2 has a pump in the fuel tank? The 1.4 engines only have the tandem pump and no pump in the tank.
 
Yes it would seem that very early (first 12000) 1.2 (and early AMF's) did have an electric fuel pump. My 2001 1.2 has no such pump. I'm surprised that replacements are available.

Early:

fuel line; fuel cooler; F >> 8Z-2-012 ... Audi A2 (A2) 2001 year Audi EUROPA 201025

fuel line<br/>fuel cooler<br/>F >> 8Z-2-012 000 Audi A2 (A2) 2001 year Audi EUROPA 201025 spare parts
audi.7zap.com audi.7zap.com

Later:

fuel line; fuel cooler; F 8Z-2-012 001>> 8Z-2-070 ... Audi A2 (A2) 2001 year Audi EUROPA 201026

fuel line<br/>fuel cooler<br/>F 8Z-2-012 001>> 8Z-2-070 000 Audi A2 (A2) 2001 year Audi EUROPA 201026 spare parts
audi.7zap.com audi.7zap.com

RAB
 
Thanks for all your help, I had a little time to work on it today and sucking air out underneath the tandem pump did the trick. It's still a bit wobbly in idle and feels weak in the throttle, although it's always been like this as long as I had it so it could just be that it's supposed to be this way. Next weekend I'll top up the fuel filter again and recheck the hoses there too, just had a quick check without lifting it up today.

Yes, there is an in tank fuel pump.I heard a whining sound coming from the back and traced it to the pump. It's real easy to replace, there's a lid underneath the rear right seat that unscrews and then it's just to pick it up. But as you said, it was nearly impossible to find a new pump. I had to become a member on some German Audi page and then order it from there, didn't really understand the whole process but paid and luckily I got it two weeks later.
 
Hi again. I had a friend help me pump fuel through to the vacuum pump in the front today while I was laying underneath the car trying to listen for air leaks. The in tank fuel pump hisses and gurgles in a way I guess it shouldn't. Could this be due to it being hand pumped or could it have an actual leak inside the tank somehow? It is a new pump, sadly I've already thrown away the old one.
 
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