1978 SC - Fix CIS or change to different injection, carbs, ITB etc?

[stormcrow]

Cfeste,

There are several things that need to be checked but you need a fuel pressure test gauge to do it. First thing I would check to see if your fuel pump has an "inlet" filter on it. If it is a newer fuel pump, it probably does.

Next I would check your fuel pressure to see if it is within specs - cold and hot. Another item to check is the fuel pressure regulator. In addition to that there is a check valve on the back of the fuel distributor that regulates pressure back to the fuel tank

Also check the fuel filter next to the accumulator. It could be partially blocked. Pull your injectors out and do a pressure test on them. It's easy to do -

You will definitely need a fuel pressure test gauge to check the fuel system out properly.

SteveKJR

"A Porsche does more then just go fast in a straight line "

[T77911S]

did i miss air leaks as the issue?

injector sleeves, Orings, intake runner boots, intake gaskets, all the AAV and AAR plumbing inthe back. all potential air leaks. and dont forget the vent system to and from the oil tank, along with the oil cap.

control pressures

compare all 6 injectors for fuel volume at part idle and WOT. if that is good, your FD should be good.


dist- i see you have had 3. correct dist? is the advance working? vacuum advance/retard working?

you get all that straight, and it should be fine.
have you done any engine mods?

carbs- i love the sound, but they are a lot more envolved than CIS. CIS has 1 adjustment, carbs have 13+ mechanical adjustments, not to mention jets, and tube selection.

i suspected my fuel dist for a long time. something kept telling to keep looking. i found a clogged injector line.

[carslutt]

im not a big fan of CIS after having it on lots of other cars. i am in the process of installing standalone EFI into my SC using an 3.2 intake manifold and lots of other non Porsche parts.

[cfeste]

I have ordered the Bitz kit, and looking forward to installing it :-) Will post updates in a few weeks!

[81TARGAPAUL]

Had similar issue with my 81sc. Pulls strong through all gears to redline, but cruising would cause a slight jerky feel. Now I know that the backlash is coming, but I simply disconnected the O2 sensor (after much reading on this forum) and the car runs great! If you are still running a cat I would not recommend, but if not, give it a try.

[70SC]

Talk to Larry at CIS Flow Tech . He's the man !!!! Larry just finished rebuilding my fuel distributer & WUR . W O W The Car runs Perfect now . Nice & smooth then Roars. CIS is not so bad !!!!!

[James Brown]

Best of both worlds is the PMO ITB's. Modern FI with that great carb sound and look.