Hi all,

I have posted about earlier stages of this problem before now with limited success so have started a new thread.

To briefly recap on history of the problem.
One month ago my fuel pump failed. It was recovered to my local mechanic and i supplied him with an after market german pump that was identical in appearance to the original pump. you can view it here http://cgi.ebay.co.uk/Brand-New-Audi...0#ht_553wt_941
My man then removed the assembly and replaced the pump unit with the new one. He refitted the assembly but when the long bolt was tightened the car died. At first we thought it was the well documented problem of the assembly not being seated correctly and therefore not giving drive to the jet pumps in the bottom of the tank that lifts fuel into the cup. He struggled with it for over a week testing various different components. He even fed a tube down into the jet pump receiver in the assembly plate and blew and sucked through it to make sure the hoses at the bottom were functioning correctly. After pulling his hair out for a few more days the car went to another two audi and VAG "specialists". Neither of them could get the car running. Finally i had to bite the bullet and take it to the stealer. After 3 hours work they confirmed that the assembly was seated properly and the pump was working properly and that the problem was in the tank and would require a further 8 hours labour (£102 plus vat per hour) to take the tank out and investigate further. Not being overly confident in them i didn't go ahead with the work and instead paid then (begrudgingly) for their time and had the car recovered back to my mechanic.
I have since got hold of a salvaged tank and had that delivered to my man. Before he started dropping the axle of my car he rigged up a "school boy experiment" with the new tank on the work bench and fitted my pump assembly to the new tank. To our dismay the same problem occurred. as soon as the assembly was tightened to the assembly plate the fuel is not being drawn.

I called the guy who supplied the pump who re-checked the part number and assured me it is the right unit and that he has sold hundreds all over the world for the a8 as they are not readily available outside of the EU. He also said he had never had a pump returned faulty and went on to say that it is German built from a reliable company.

So, that leaves us with a few possibilities...

1) The salvage tank has the same problem as mine.
2) The pump is wrong or defective (despite the sellers assurances)
3) The assembly has somehow failed or is blocked on the jet drive return side.

personally i favour the later.

My questions are ....

Is it possible that crud has been sucked up from the bottom of the tank, blocking the return side of the assembly causing the pump to run dry and fail?

If so, where is the likely point of blockage? (as you know the internals of the assembly are mostly hidden from sight.)

For a week or so before the pump died i did hear a whine from the trunk just before cranking but figured it was the boot lock that ive had problems with or the arial. It did run low on fuel a couple of times too.


I drive a 97 A8 2.8l (yes, the european one)

Many thanks in advance.

Including the hire car, recovery costs parts and audis bill im up to nearly £1000 now. This must be the most ridiculous fuel delivery system ever designed....

jamie (stooshmobile)

 

Dude.. get a different pump...




...try it. If it works, tell that ebay F where to go...

 

that's why I got the OEM unit 600$ the horror stories of getting it all together properly by just replacing the internal pump wasn't an option
you have probably spent that much at this point to have bought an complete assembly and had it installed with a warranty and let them worry about it
"hope you get to the bottom of it"
assembly into the housing would be my guess

 

Yeah i hear ya.
Up until now i have been unwilling to pay £430 for a OEM unit if there was a possibility of not fixing the problem.
Ive managed to find a salvaged assembly with the pump in now for £95 delivered. If that goes in ok and works then it rules out the tank but still doesnt tell me wether it was the pump or the assembly!
Also, i dont think that having this done by the stealer would have turned out any better... My experience with them has been very poor up to now. They even admitted to me that no one in the workshop had ever worked on a D2 before!!!! Simply ridiculous.

We shall see what the salvaged assembly reveals. Im gonna write a book about this when im done....

Thanks for your replies

j

 

I didn't t do the stealer either just found me a good *AUDI* mechanic not everyone can work on our cars I have been an auto electrician for the last 22 years and did not want to screw with that few pump although I pretty sure I could do it
.Just remember stay with the problem at hand and dont stray to other things if the fuel pump was diagnosed as the original problem correctly then the problem is more than likely there
lastly have you checked the polarity + & - of the pump wiring. If you bought it in europe it could be reversed.
Read this on another board

 

You can "prove" that the pump is in fact seated correctly. Your mechanic will need a borescope which he likely has.

If you remove the driver side (US version) of the tank inspection panel, you can snake a borescope across the tank to the fuel pump side. You can actually watch the pump pick up tube get inserted into the receiving end in the tank while the housing is being rotated into place.

This is how I did it and it proved beyond a doubt that this was not an issue.

It appears that you have the correct pump but I would be suspect of that before the tank or tubing being the issue. In the US, we have been ordering the pumps from a place in the UK which gets the OEM VDO pumps.

Plenty of wrong listings on eBay for the A8's.


Bob

 

Thanks greglo, I did mention the polarity issue to my mechanic, but surely if the pump is working at all then the polarity must be right. I did read one unanswered question of the possibility of it running backward if the polarity was reversed. My pump will pick up fuel from the cup and send it to the rail. The problem seems to be that fuel is not being pumped into the cup.
I have no doubt that the fuel pump was the original problem. My concern is that when the assembly was removed and refitted (dozens of times now) that something has been disloged/broken. I am only looking at other things now because the new pump has been fitted yet the car doesnt run.

Thanks again J

 

Cheers Bob, He has checked the seating with the camera. One of the first things he did.

I would be interested to have the details of your uk supplier of the VDO pumps.

If the pump is at fault i want a refund!!!

any details gratefully received.

j

 

Rough notes:

- If you're in the 150k range, I would strongly consider changing the pump before it leaves you stranded. It will, and at this mileage, you're on borrowed time. At a minimum, order the pump and leave it on the shelf if you plan on keeping the car.

- Sender unit cap is opposite hand
- If long threaded bolt does not thread in easily, DO NOT proceed. This is noted in the Bentley.

Order from:
ignitioncarparts.co.uk

Electrical Fuel Pump - PFP405052002001Z

Total (inc VAT + P+P): £178.80

My shipped price was $251 and took a total of 8 days. I don't think they normally stock the pumps so it took a couple of days to get from Germany back to the UK for shipping.

If you need the "gasket set", the part number is 4D0-298-133-C. The price is about $105. The kit includes the o-rings, crush washers,lower pump seal and a crimp hose clamp.

The sending unit cap and seal are 4D0-298-135-B for about $13.
Bob


2000 A8, Silver, D3 18's with Yokohama Avid S4's. Nav Plus
2000 A8, Black and basically stock

 

Make sure that you have a pump with two pipes on the bottom side. The bigger is the input the small pipe is output to the spider venturi system.
<img src="http://audipages.com/tozo/fuel%20pump%20dimensions.JPG">