Was having a job done on my car and decided to have the fuel filter changed, since it had never been done for the life of the car. After fitting the fuel filter the Mechanic couldn’t get the car to start, and told me he would have to put the old one back on. It’s the type of filter that has two pipes at one end, and one pipe at the other.

Some huffing, puffing, and swearing later, a suggestion was made to swap the tubes around at the two pipe end. Vroom! Car starts.

So if you fit a fuel filter only to find your car will not kick into life, try the old swaparoo with the tubes. I know it’s obvious, but it may just help someone out who thinks they may have bought a duff filter. Apologies if this is something that’s well known and already posted on here.

Old Fuel Filter: Blue tube on the outer pipe

New Fuel Filter: Blue tube on the centre pipe

Your mechanic is talking through his ar5e

You need to install the pipes the correct way round and prime the system (basically ignition on and off around 10 times)

Edited 30 January, 201412 yr by BigJase88

Your mechanic is talking through his ar5e

You need to install the pipes the correct way round and prime the system (basically ignition on and off around 10 times)

 

 

Well you can see by the pics of my filter that the tubes have been swapped around. It may have been one of a faulty batch of filters etc. Not everything (if anything) in life is black and white.

This is a filter with a built in pressure regulator, the blue line is the tank return line and the black is from the pump, swapping them round should make no difference, however bleeding the fuel rail while cranking would have speeded up the start.

Edited 30 January, 201412 yr by sepulchrave

Here's some info (from a pdf about 1.2 engines, but looks the same arrangement) showing the internal workings of the filter/regulator:

 

 

 

I'm not sure it works very well at all if feed and return pipes are mixed up, like in your first pic.  How does the fuel pressure from the pump open the diaphragm valve?

If it does succeed, the fuel coming out the outlet towards the fuel rail will be unfiltered won't it?

 

Maybe your filter is different?

Here's some info (from a pdf about 1.2 engines, but looks the same arrangement) showing the internal workings of the filter/regulator:

 

 

 

I'm not sure it works very well at all if feed and return pipes are mixed up, like in your first pic.  How does the fuel pressure from the pump open the diaphragm valve?

If it does succeed, the fuel coming out the outlet towards the fuel rail will be unfiltered won't it?

 

Maybe your filter is different?

 

 

 

Thanks for the info. The first photo is the original set up from when I bought the car a couple of years back. The second photo is the swap around. All I know is that it didn't start until the guy put the tubes on the way he did in the second photo. Are you saying the original (pic 1) set up appears wrong, or the second one?

Well my understanding is that the feed pipe from the pump is the black one, the return to the tank is blue. So your first pic seems to show them wrongly connected.

Well my understanding is that the feed pipe from the pump is the black one, the return to the tank is blue. So your first pic seems to show them wrongly connected.

 

Understood. Thanks very much for that

You're welcome.

The blue line is always the return line, so the first picture is wrong.

The blue line is always the return line, so the first picture is wrong.

 

Thanks. So it appears that I've been driving around for two years with the filter connected wrongly  

Not always the case, the new non oe filters do have the pipework differently sometimes, but it will show on the filter.. Like yours does with an arrow on the side showing in. My guess is someone has swooped over the blue and black pipes on the pump unit as they are easy to get mixed up.

Cheers

Apparently,  the filters are sometimes made with the pipes the wrong way around. At least according to this thread...

 

http://www.briskoda.net/forums/topic/211977-fabia-1416v-fuel-filter-problems/

Looking at the external shape versus the sectioned diagram, surely the central lump bit always has to have the pressure valve return spring in it, so must always be the return connection. :wonder:

I can see that if the pipes were swapped at the tank, things may get confusing at the filter...

Looking at the external shape versus the sectioned diagram, surely the central lump bit always has to have the pressure valve return spring in it, so must always be the return connection. :wonder:

I can see that if the pipes were swapped at the tank, things may get confusing at the filter...

 

The filter regulator design makes incorrect manufacture impossible as Wino says, basically as soon as the fuel pressure in the filter body hits 4 bar the spring will compress and allow excess pressure to bleed back to the tank, it won't allow fuel in since it's effectively a non-return valve unless the mechanism fails, in this case if the mechanism had failed then the car would be using unfiltered fuel with it connected up the wrong way round like in the first picture. Testing for pipe reversal at the tank is easy, put the black and blue pipes into a jam jar and flick the starter, fuel will only come from one of them.