Fuel Pressure 1989 SC

[piscator]

After two mornings searching, I've found numerous fuel pressure specifications, but not one definitive pressure spec for the 1989 SCs! Maybe this is highly classified information, but if someone is willing to let me in on the secret I'd be most appreciative to learn:

System Pressure:
Control Pressure: Cold and Warm
Residual Pressure: (usually after 10, 20, minutes)
Fuel Volume: (usually after 1 minute)

I'm trying to help a distant friend and don't have a manual for the later year cars, my SC is a 1979.

The correct fuel pressure for the 1989 SC may depend on the specific WUR installed, but I don't have that information, yet. If someone could give me pressure specs that are 'in the ballpark' it would give us a starting point.

[Flat6pac]

The 89 is a Carrera and has an fuel pressure about 40# across the injection system
There is no warmup reg as your S.C.
Carrera injectors are electronic, individually wired
Bruce

[RarlyL8]

1989? Are you sure about the year?
SC was 1978-1983, Carrera 1984-1989. Carrera has Motronic EFI, not CIS.

[piscator]

It's a Carrera. Sorry, my mistake! My daughters might tell you that I haven't quite gotten to the 1980's -- yet.

No warm-up regulator? Huh?! Learn something new every day! Thanks for the help!

[piscator]

Bruce, you said 40 psi "across the board" -- does that mean there's not a separate specification for:

System Pressure
Control Pressure
Residual Pressure
Volume

like there is on the earlier cars? That's confusing me.

[proporsche]

this might help you....

[boyt911sc]

Originally Posted by piscator

Bruce, you said 40 psi "across the board" -- does that mean there's not a separate specification for:

System Pressure
Control Pressure
Residual Pressure
Volume

like there is on the earlier cars? That's confusing me.

Robert,

It is nice to offer help to your friend or to anyone else. But if you could not distinguish the difference between an SC and a Motronic engines, you are not in a position to give such a technical advise. To test the fuel pressures for both SC’s and 3.2 Motronic’s, you need to run the fuel pump/s with a fuel pressure gauge installed.

That means you are to break or open the fuel line to install the appropriate pressure gauge. There will be fuel drips on top of the motor. Here are the fuel pressure spec for your friend’s Carrera 3.2 motronic motor:

FP running (engine off), no vac applied..................36 +/-3 psi.
Engine running vac connected (normal setting).......29 psi. Or you could do this test without running the engine just the FP but has to use a handheld vac pump.

Attached below are the instructions for the fuel pressure spec Carrera 3.2:





Tony

[piscator]

ProPorsche, thank-you kindly – that’s very helpful!

Tony, thank-you for the compliment and for such detailed information! Since I’ve never even seen a Motronic engine, you’re probably right that I’m in no position to offer advice. Reading several on-line manuals and various threads on the subject mislead me into thinking it was similar to the fuel tests I’ve performed for decades on my 1979 Porsche and various BMW’s. I’ve directed my friend to this thread for correct advice!