C3 Fuel line check valve

[TGJR]

Can anyone shed any light on the correct type of check valve (if any) should be fitted to a 1976 Carrera 3.0 and also where exactly on the system it should be located.

Thanks,

Thomas

[Kenny Senior]

The check valve on a CIS car is usually on the outlet of the fuel pump. A banjo fitting on the fuel line slides over it then there's a cap which secures it.

[Type911]

Im sticking with my initial response, not fitted on a 1976 car

[TGJR]

This situation came to light when my fuel tank got damaged by a stone and when it was removed for repair the original banjo fitting was corroded so the fuel line was cut just after it. This resulted in an unexpected high pressure squirt of fuel, presumably because the original banjo fitting had a check valve function as well.

I could see in parts listings a banjo fitting with check valve priced at circa £60 but this is listed for 74 cars (mine is a 76 C3) and there was an inline check valve priced £26 listed for 78-83 cars. Being a tight northerner I purchased the cheaper one as in my mind a check valve is a check valve regardless of whether it is an inline part or built into the banjo.

Since fitting this the car starts fine cold, fine after a short stop but takes quite a few spins before firing up when it has been sat for 30-50 mins. Before all this happened it always started on the first turn of the key regardless.

The sure fire fix would be a new fuel line complete with banjo as per OEM for a C3 - unfortunately from my research this is a no longer available part! I would be very interested to know if anyone has any knowledge/experience of this and if so, how to get it sorted.

 

[johndglynn]

The cheaper fuel pump check valve is SCs only as you say. Tuthills changed the check valve as cheapest first step on my first SC when it had a hot start problem but it turned out to be the accumulator. I would bet that whatever was first used on C3s will still be available, just not through Porsche.

[TGJR]

On ‎22‎/‎05‎/‎2017 at 10:29 PM, johndglynn said:

The cheaper fuel pump check valve is SCs only as you say. Tuthills changed the check valve as cheapest first step on my first SC when it had a hot start problem but it turned out to be the accumulator. I would bet that whatever was first used on C3s will still be available, just not through Porsche.

Thanks. If anyone knows where to source the correct part for a C3 please let me know as I am struggling.

As I understand it, the part I need is a fuel line with an integral banjo/check valve which connects to the fuel pump with a banjo bolt. I still can't work out in my head how this is different to using a check valve from the SC in the same position but as my car no longer starts as easily from hot (after sitting for 30-60 mins) I presume there must be a difference in either the check valve or the actual fuel line.

The car will start after a few spins of the engine but sounds a bit like a Beetle for the first 5 seconds when the fuel is not getting to all pots.

[Type911]

Maybe time to look elsewhere? Fuel accumulator?  

[flatsix777]

Really you would be best to check your system and control fuel pressures, both generally but specifically the rate of decay of system pressure after shut diown. The manual will show the spec for residual system pressure after (I think) 10 and 20 minutes. 

I'm not sure about a 76 Carrera but I think that the fuel distributor also plays a part in maintaining system pressure alongside the accumulator and check value on some of our cars. 

Best to systematically chase down issues with CIS. 

David

[johndglynn]

Pressure check is the only way.

I will talk to Steve at JZM about this next time I am in - he has the factory manuals so should have some pointers on check valves.

8 hours ago, TGJR said:

The car will start after a few spins of the engine but sounds a bit like a Beetle for the first 5 seconds when the fuel is not getting to all pots.

This was very similar to my accumulator issue but the check valve has the same symptoms (unsurprisingly). 

[TGJR]

Just spoken to Mike Bainbridge about this and as he recalls the check valve is in the banjo bolt on the C3. I subsequently called Porsche Kendal parts and they can get the pressure line with banjo from Germany but can not find a listing for the banjo bolt expect for a turbo one. The turbo has 2 fuel pumps and as such the banjo bolt is without check valve at the front end so not suitable. They are going to look into this further and get back to me.

As is often the case, a rare model like the C3 that was only produced for a couple of years poses some challenges in the parts department! Probably best, as suggested, to take it in for a pressure test.

[lemon yella RS]

Just to help here , hopefully my long ago recollection is sound. Indeed it's a banjo fitting on the end of the fuel pump . I think from memory the pump has a straight through fitting as standard and there is a replacement fitting that can be used. Memory Fades at what , but  either from an SC or other cis car. I Had a MK1 golf GTi at the time might be worth a look at parts for that.

 

 

Should add my C3 was a 77 and didn't have the check valve as standard. 

 

 

[lemon yella RS]

Further memory recall. I don't think it's a banjo fitting I have a picture in my head of a threaded fitting that screws into the pump ?