I recently had a most unpleasant experience with the fuel system in my Audi 5+5. No matter what I replaced it would always run very poorly under wide throttle openings and after a longer driving period, say 30 minutes, would become undriveable. Here is a recollection of my trouble and sleepless nights of the past 18 months.
After leaving for Canberra January 1994, the weekend of severe bushfires, I managed to get as far as Mittagong when the car lost all power and acceleration on a steep climb. My first reaction was "**** its a slipping clutch" but over the hill and down the other side the car ran okay, so I continued to the Mittagong exit and when the problem occurred again I noticed the revs.. dropped again so that eliminated the chance of a clutch.
In Mittagong I pulled over and walked around the car and stuck my head under the bonnet to see what I could find. I noticed there was a very loud, strange noise coming from under the car near the rear wheels. When crawling underneath I discovered this was the fuel pump and figured, I had the air conditioning on and was pushing the car very hard considering the outside temperature. After leaving the car for approximately 15 minutes I started it again and it ran fine so I pushed on to Canberra. Passing through Lake George I had a similar problem but managed to arrive at my destination only slightly later than expected.
Putting the problem down to a case of dirty fuel I drove around Canberra all weekend without a problem. On the return journey, the problem was only slightly noticeable around Campbelltown so I dismissed any thought that it was a permanent problem and continued driving the car.
A few months later I took the car North to Forster and experienced the same problem. When arriving back in Sydney I purchased a second hand fuel pump as after speaking to a few people I was convinced this was the problem. The new pump cured the problem for a few weeks as I was only driving the car in traffic so not utilising wide throttle openings.
On the way to a committee meeting I gave Steve Carter the keys and offered him a drive to the meeting. Not knowing the car, Steve gave it more acceleration than I had been doing and the same problem occurred.
After checking the fuel filter, and finding it full of dirt and sand, I linked the problem to the fuel I purchased the night of the committee meeting.
A new fuel filter, another second hand pump, new injectors, and a cleaned fuel tank over the next few months failed to cure the problem. After trying yet another fuel pump and replacing the last link of wiring to the pump the car ran OK for the next year or so.
March this year and the car not only had a throttle problem, it also started cutting out and not restarting after approximately 45 minutes of driving.
The cutting out was traced to burnt wiring in the fuel pump circuit in the fuse box, and an inline fuse holder. The inline fuse holder would get so hot you had to drop the fuse onto the floor for approximately 15 minutes till it cooled enough to be repositioned in the holder.
After replacing the wiring in the fuse box and using a blade fuse holder, thanks to Phil Lander and Rod Young, the cutting out problem was solved but the throttle problem was still there. This was also what we thought caused the wiring problem.
After trying a brand new fuel pump I thought I would cure the problem for sure. Unfortunately this was no better and so I was ready to flog the heap to some poor unsuspecting dealer and get my Beetle back on the road. Something with no fuel injection and no complicated electric’s, what a dream.
After pondering for hours over my 5+5, still passionately attracted, I decided to give it another few months. Determined to find the problem I again had the tank cleaned and the filter before the pump replaced. A hot power wire to the fuel pump kept convincing me this must be the problem. After this did not solve the problem I decided it was time for a simple logical approach, start at one end of the fuel line and check everything until I reached the other.
Testing fuel delivery at the fuel distributor I discovered it could not be between there and the engine as there was not enough fuel getting through the distributor. Thanks to Darryl Donald I sourced a photocopy of the parts catalogue showing diagrams of the entire distributor and fuel line.
As a chance I discovered there was a filter on the inlet to the fuel distributor. After removing and checking this filter I discovered it was contaminated with sand. 4:00 on a Saturday afternoon and there were no dealers open to source a replacement item so I decided to clean the filter with the limited resources I had.
Armed with a jam jar of petrol and a 12 volt tyre inflating air compressor I attempted to blow the filter clean. Much to my surprise this worked and so I refitted the item in the car.
Keen to test my handiwork I took the car for a drive. After 15 minutes and no sign of problems I decided to give the car a hard drive and still no problem, except a Fairlane nearly pulling out in front of me halfway through a tight right-hander. I avoided the other drivers mistake and continued to drive around my home suburb of Lugarno for about an hour. So excited with my achievement I drove the car all day the next day. I still get a buzz out knowing I can repeatedly plant my foot to the floor and the car will respond favourably.
I must thank Rod Young, Phil Lander, Dr Darryl Donald, Steve Carter, Ron Croft and Ted Savage and my wife for their help and patience during the encounter.
Paul Tagg