Don't want lean all over the place. That sounds hot and dangerous. Where is this test plug that I hook the dell meter to? Does the other lead go to ground?

I don't believe the pump is running with the ignition on. When the car is cold it is quiet prior to starting. When it gets hot (and engine is off with ignition on), the buzz is loud and comes from the vicinity of the air intake box.

Tony,

No offense taken. Let's all get this info right. I'm just trying to help out, but I realize it's no help to anyone if false info is being shown here.

Actually you remind me of something else. In the PP catalog there are 2 accumulators showing. One for 78/9 w/ one hose on the bottom and 2 on top, and one for 80- w/ 2 hoses bottom and 1 on top. Does anyone know why this is? Is it just the way the photo was taken, or do the 2 mount differently? There is also a significant price difference. I'm assumimg the hose that is usually removed is the single one on the 78/9 and the same one on the top of the 80 one. In this instance no fuel would drip out anyway, since it is upright. Is this correct?

That looks like a glitch IMHO.
The 78-79 Accumulator has 2 top and no return line on the bottom.
The 80-83 Accumulator has 2 top and one return line on the bottom that Porsche added for safety reasons in case of internal leaks.
Both types work fine but if you want to use the later type on an earlier SC, the bottom opening needs to be capped since there is no fitting to enter into a return line.

Gunter,

I'm thinking of using the earlier one on my engine. It is something like $180 less. Can I do this by capping the lower fuel return line (if I have one now)?

I'll have to look more closely @ what I have currently.

Obviously if there is no line off the bottom then there would be no way to check using the lower line removal procedure anyway.

SC Fuel accumulator.......
 

Gunter,

So far, the four (4) SC cars ('78-'79) I know in my area all have three (3) ports fuel accumulators including the '78 spare motor I bought from a member. I've seen the two (2) ports FA in early CIS cars ('74 or '75). Plus Pelicanparts sells these fuel accumulators (3-port) for '77-'79 CIS cars (see Catalog).

Tony

Where is this test plug that I hook the dell meter to? Does the other lead go to ground

The test plug is under the plastic cover on the left of the engine compartment. It is a loose wire with a rubber cover. Inside you will find three prongs, the prong with the green white stripe wire goes to the dwell meter "coil" wire. Most dwell meters will also have a red and black wire for +/- battery. You can use the heater blower fuse under the cover for + 12v and the engine block for ground. CIS lambda will speak to you, not quite OBDII, but much better than guessing. It will tell you if the system is functioning and give you a proxy for adjusting the open loop mixture. Everything you need to know has been posted here, search for CIS lambda and read the archives. If it is the FV that is buzzing loudly, you should be able to feel it by reaching around the air box.

Tony,

Do you know if I can use the 78/9 one in my 80 mod engine? Any downside to this?

Fuel accumulator.......
 

Paul,

YES.You could interchangeably use these fuel accumulators in SC CIS engines. Downside? None I am aware off. If you ever get a chance to dissect these fuel accumulators (for SC's and 2.7 CIS), you'll notice that the internal parts are almost identical. Two ports to three ports or vice versa will have no adverse effect in your system. I've used these FA's interchangeably for years without any ill effect. HTH.

Tony

Fuel Pressure is bleeding off. Check valve in the fuel pump neck needs to be replaced.

I agree with Tony re: interchanging FA between different years might very well be possible; try it.
However, I'll give Bosch and Porsche the last word on FA's; there are obvious differences between the years. :

0 438 170 009 = ’77-‘79
0 438 170 005 = ‘80
0 438 170 031 = ’81 – ‘83

There must be reasons why there are diffent configurations and I trust that Porsche made the right decision on which type to use for various years.

The FA from a '78 I bought had only 2 ports on top, nothing on the bottom.

Page 200-3 in the Bentley shows a FA in the scetch for '78-'79 CIS with only 2 lines on the top, no line on the bottom.

If you don't have the "T" on the return line, you'll need the FA with only 2 lines, no return.

Thanks for the info, Tony & Gunter.

Apologies for the hijack.

So..... What was the fix?

Got the car warm this weekend, turned it off, turned the ignition back on, and the buzzing started and the car wouldn't start. Pulled the relay under the passenger's seat and the buzzing stopped. Car still wouldn't start of course. Does this mean that the frequency valve (fuel timing valve) is bad? Here at pelican they only offer OEM and it's almost $500.

Found the frequency valve elsewhere for $186. Is it found by removing the fuel distributor?

Is it in the exhaust manifold?

No,
The FV is in the fuel line behind the throttle body and it has an electrical connection.
It's a little tough to replace because of the location.
The frequency valve is specific for the year, make sure that you get the right one.

It could also be that the FV is good and the brain (ECU) under the seat is acting up.
Clean the electrical connections for the ECU and relay.
Before replacing expensive parts, I would have a Porsche shop diagnose the problem.

I don't have a real Porsche dealer here in Huntsville, AL. Have a beamer dealer with a few porsches, though. I thought that they would be expensive, and the car needs a lot of work, so I figured I might as well start learning. My Bentley manual is in the mail. Someone requested pictures of the car, and I still plan on doing so. At the moment the flash on my camera has quit.

Anyway, what might the dealer charge for a diagnosis?

The FV makes a high-frequency, slightly-varying sound when the car gets warm, but while the engine is off. It then will not crank. As I said before, pulling that relay, (I guess that's for the O2 sensor?) makes the high-frequency noise stop, but the engine still will not start.

By the way, I will clean all connections when I get home. Definitely a good suggestion, and a cheap one at that. Thank you

The CIS with Lambda is complex.
The power for the relay under the seat comes from the same fuse as the interior lights and glove compartment, clock etc.
The relay then powers the ECU.
Clean all connectors on the ECU and the relay.
I clean all electrical connections and use dielectric grease.
Cost for a diagnoses? Don't know.