I am putting in the fuel tanks and lines for my 71 2.2S. I am following some very good posts on the early s forum about the pipe routing and the correction to the Porsche diagrams. Buried in some of the posts is a reference to a 1.5mm regulator on the return to the tank somewhere either in the t piece or in the pipe. Both the t piece and the banjo were NLA from OPC so I found my own pieces but they are just 8mm pipe fittings.
I am assuming that the restriction is from the t to tank on the return to effectively be a 'pressure relief' on the return to the pump, but would be good to confirm my understanding. If so I can make something that will fit in the pipe bit less than 8mm dia and 1.5 hole.
Bummer that I only found that information after i put 2 gallons of petrol in it!
Hi, I struggled to find info on this as well believing the restrictor was there to build pressure in the fuel circuit. Even getting to the point of looking at using carburetor jets in the return line as an alternative and suggested on Pelican. The particular problem I was trying to solve was hot starting, ('69 S upgraded in the 1990s to '73RS spec). In my case it turned out that the pressure valve on the side of the fuel filter console had some residue built up inside it preventing it from sealing and thus limiting the build up of fuel pressure. Taking it off, cleaning it out and it sealed perfectly. Once that check valve was working properly the hot starting problem disappeared and the return to the tank has no additional restrictor on it.
Not sure if that helps, but if hot start is your problem may be worth checking the filter console check valve.
Thanks all that is great, since the post I took the pressure at the MFI pump end and it was at about 12 psi between the bottom of the filter and the MFI pump which seems in spec which is good so I have been less worried!. Given what I have seen the restrictor seems to in the fuel fuel housing and not at the fuel tank end as was suggested.
Hopefully close to the start up of the new engine, just a bit of ignition to sort out
IJD wrote:Hi, I struggled to find info on this as well believing the restrictor was there to build pressure in the fuel circuit. Even getting to the point of looking at using carburetor jets in the return line as an alternative and suggested on Pelican. The particular problem I was trying to solve was hot starting, ('69 S upgraded in the 1990s to '73RS spec). In my case it turned out that the pressure valve on the side of the fuel filter console had some residue built up inside it preventing it from sealing and thus limiting the build up of fuel pressure. Taking it off, cleaning it out and it sealed perfectly. Once that check valve was working properly the hot starting problem disappeared and the return to the tank has no additional restrictor on it.
Not sure if that helps, but if hot start is your problem may be worth checking the filter console check valve.
Hi, that's interesting, I have had a hot start problem for some time, and this could be the issue. Is it easy to remove? take whole console out of car? difficult for me to have a quick look as car is away whilst I am building garage. Cheers Ian
It's the size of your thumb, like a banjo fitting really with a strainer mesh. Expensive at around £90 quid. Don't re-plate these when doing your resto guy's. Always fit a new tin can filter too.
The 30 second fuel return test from the MFI pump is an easy test that will confirm the function. Described in the workshop manual.
IJD wrote:Hi, I struggled to find info on this as well believing the restrictor was there to build pressure in the fuel circuit. Even getting to the point of looking at using carburetor jets in the return line as an alternative and suggested on Pelican. The particular problem I was trying to solve was hot starting, ('69 S upgraded in the 1990s to '73RS spec). In my case it turned out that the pressure valve on the side of the fuel filter console had some residue built up inside it preventing it from sealing and thus limiting the build up of fuel pressure. Taking it off, cleaning it out and it sealed perfectly. Once that check valve was working properly the hot starting problem disappeared and the return to the tank has no additional restrictor on it.
Not sure if that helps, but if hot start is your problem may be worth checking the filter console check valve.
Hi, that's interesting, I have had a hot start problem for some time, and this could be the issue. Is it easy to remove? take whole console out of car? difficult for me to have a quick look as car is away whilst I am building garage. Cheers Ian
hi Ian2.2S. Yep dead easy to remove, easily accessible at side of filter console so no need to remove console itself. Mine was so bad you could blow through both ways with no restriction. Poking about with a scriber then carb cleaner and compressed air and full functionality restored. Hope that helps.
