Regards the CDI box, when you're in the engine bay look to your left, there is a black plastic cover with a wing-nut fastener, take this off and you will find some relays and a box that looks like this



With the ignition on this unit will hum, quietly, if someone is mistaking this for the fuel pumps running then they are most likely spiderman and have superhuman hearing.
I had new pumps fitted to my car about a year ago, the shop left the wire disconnected from the fuel head (accidentally), the pumps were REALLY obvious with the ignition on without the engine running! Another shop reconnected the wire whilst i was stood there and the car was silent until i fired her up.
You do sometimes get some noise from the fans when you turn the ignition on, i guess the best way to check noises is to make sure you have every heater control turned off, including the one behind the handbrake, if you are still hearing something before the engine starts then something needs looking at?

 

Ok all and thanks for the info...I came home and opened up the hood and turned the key 3/4 of the way....and I got nothing...Nothing meaning...Just the normal hum.. This hum came from under the airflow box...Is this where the fuel pump is..

Why do I also hear another hum somewhere else…Sitting in the passenger seat…Does the car have 2 fuel pumps...Sorry for the uneducated question...or is this something else...

I did not get the crackling sound of an electrical nightmare as I did before... I turned the car on and off 15 times and did not get what I thought I heard…Thankful….but still worried…

I looked around and did not see anything out of the ordinary like crossed wires, singed wires, etc….Everything works that worked before….

A question to the peanut gallery (No offense) does the 79 model come with a stock CIS….and please explain the difference between CIS CDI…or do I have both…I did not see anything newer than what I feel came stock…

My PO told me to aspirate meaning turn the key ¾ of the way to build up pressure prior to starting….Is this true….because I can not start the car if it is cold without allowing the hum to hum for awhile…When it is warm(after driving it, not warm weather) it will start just like any other turn key car but it does not feel right….or am I just losing my mind now that I have had people chime in on a local forum regarding this…

I did here the crackling sound once before but was very short and it went away after the car warmed up…The car did lose pressure maybe boost…I did not kick in the turbo only when I pressed on the gas…Like it was going to stall but came back to life quickly….So I know something is about to go…

Would the DME be an issue….Grrr…..Thanks again all…..


BTW the fuel accumilator has been changed 2.5 years ago.....

 

I ran into the same thing....the shop left the wires off the fuel head (plastic elctrical fitting with green wires?) so I put the connector back on, but it still whines before I start and have the key in the 3/4 position before start. I have an MSD unit but the sound is coming from the front area and the MSD is in the back....but a definite whirring sound like fuel pumps. There's one in front and one in the rear.

 

I'm no expert, but here's my simplistic explanation/clarification: CIS refers to the fuel injection system. CDI refers to the ignition system. Our cars have both. However, our cars don't come with DME. That's a "later" form of fuel injection system. CIS is an "earlier" version which is found in our Turbos. Actually, my earlier and later references are a bit of a misnomer, as Porsche was making DME Carreras and CIS Turbos at the same time in the 80s. But there's no DME relay to go checking in our cars.

What sound are you hearing, exactly? I find that in my car, when I turn the key in the ignition (but before I actually actuate the starter) I can hear a high-pitched electrical whine. Almost like feedback from a speaker. That's the CDI box (it supplies the charge that goes to the spark plugs). I also hear that for a couple seconds after shutting down the motor. That's a different sound than the buzz/hum of the fuel pumps, which I only hear when the motor is actually running.

 

i have new every thing, new pumps new fuel head flow checked all the injectors all the relays wired correctly new acumulator. when its been in the sun all day or warm, I have to turn the key at 3/4 and wait a few seconds I get a hum then it stops like maybe a fuel pump pressurizing the system then it fires right up. if I turn the key to start without waiting it cranks for a while before it starts. no idea why it does that.

 

+1 to JBL's description.

Hey Jonathan what's the status on your beast mate?

Cheers, Jim P.

 

Hi Jim, the engine has been in the car, just to check for fit etc and to take measurements for the oil tank, we are going with the 993 oil tank as it means we can run duel oil filters and it just fits better (or needs less modifying). My shop has only being doing bits and pieces between jobs, but from Friday they are on it none stop for a week so should see some real progress by the end of next week. I must admit i'm a bit pensive about having that much torque in a torsion bar car. Don't want to hijack this thread so it would be better to discuss this stuff on my thread. Hope you're well matey, speak soon

 

Noah.....What year is your car

 

'87

Again, I'm not too experienced in the earlier Turbos, but from the stuff I've read, I don't recall there being big differences (at least regarding what we're talking about) between early and late 930s.