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Fuel injection layout (K-series)
Humbug - 24/2/05 at 08:03 AM

I have seen a couple of posts on fuel injection layout but nothing specifically about K-series. On other forums (e.g. Blatchat) I have seen something like:

Rear:
Tank->Filter->Low pressure fuel pump (e.g. Facet)

Engine bay:
Swirl pot->high pressure pump->filter->fuel rail->return to swirl pot->return to tank

I'm not sure why the extra low pressure pump is needed - one of the recommended high pressure pumps like a Golf GTI or Vauxhall SRi would not originally have had a low pressure feed as well?

A recent post here went something like Tank->filter->pump->fuel rail->return to tank, which seems a lot simpler, or am I missing something important about flow rates, pressure or something?


nick205 - 24/2/05 at 08:14 AM

For what it's worth the Pug 205 GTi uses the following set-up...

Tank >> Pump >>Filter >> Pressure Regulator >> Fuel Rail >> Return to Tank

From memory I believe the Golf GTi uses the same layout as well.


... The fuel pumps are high pressure ones!
HTH

Nick

[Edited on 24/2/05 by nick205]


britishtrident - 24/2/05 at 08:20 AM

Low pressure pump is required if you use a swirl pot, the simplest way is to use an in tank hp pump -- the one from the Rover 620 is quite easy to fit.

[Edited on 24/2/05 by britishtrident]


colibriman - 24/2/05 at 09:48 AM

quote:

I'm not sure why the extra low pressure pump is needed - one of the recommended high pressure pumps like a Golf GTI or Vauxhall SRi would not originally have had a low pressure feed as well?




the way I understood it was that the swirlpot and high pressure pump at the engine is used to avoid having the return fuel line to the tank.......right or wrong?

[Edited on 24/2/05 by colibriman]


clbarclay - 24/2/05 at 10:00 AM

Not sure how relevent this is to petrol injection but most deisel injection systems need some sort of low pressure pump to make sure the high pressure injection pump is filled propely in between injections.


britishtrident - 24/2/05 at 10:46 AM

quote:
Originally posted by clbarclay
Not sure how relevent this is to petrol injection but most deisel injection systems need some sort of low pressure pump to make sure the high pressure injection pump is filled propely in between injections.



Exactly right, with electronic petrol the low presure pump isn't needed if the high presure pump is in the tank.


britishtrident - 24/2/05 at 10:49 AM

quote:
Originally posted by colibriman



the way I understood it was that the swirlpot and high pressure pump at the engine is used to avoid having the return fuel line to the tank.......right or wrong?

[Edited on 24/2/05 by colibriman]


Not really if the return line isn't fitted the fuel rail pressure regulator won't work properly, it also bleeds the air out if the tank has been emptied.


Humbug - 24/2/05 at 11:25 AM

... I should have said: the GTI pump apparently has a swirl pot built in - does that make any difference to the need for a low pressure pump at the rear?


stressy - 24/2/05 at 11:58 AM

Just try and gravity feed the pump


Humbug - 24/2/05 at 04:01 PM

quote:
Originally posted by stressy
Just try and gravity feed the pump


Thanks - I still have the previous info you sent me on the K-series. Do you (or anyone else?) think I can get away with only having the high pressure pump (with swirl pot) at the rear? It just seems unnecessarily complicated to have to have 2 pumps, etc.)

Anyone got any specific part numbers/suppliers for swirl pots, high pressure pumps?


Stu16v - 24/2/05 at 07:21 PM

The low pressure pump is indeed there to supply the swirl pot. In tank pumps/gravity fed pumps are fine, except for one thing - fuel surge. A swirl pot will prevent (read cure) fuel surge, whereas it is likely to take quite a complicated design of tank to prevent it otherwise. Remember this type of sports car is capable of generating far higher cornering forces than your average tintop. Not only will your engine not like running weak because of starvation, but it wont do your injection pump or injectors any favours either.

However, as you say, the GTi pump has the swirl pot built in, with careful positoning is reported to do the job fine.


Humbug - 24/2/05 at 09:29 PM

"Careful positioning" presumably meaning below the level of the tank?

then do away with the low pressure pump, you reckon?


Humbug - 7/3/05 at 02:43 PM

Does anyone know the part number and a supplier for the Golf GTI combined high pressure pump and swirl pot?

Thanks