Fabio421

The title pretty much says it all. My 78 CIS car will stall if you blip the throttle abruptly and also between shifts when you are driving it. It seems like the sudden closure of the throttle plate is what is bringing this on. WHat could be causing this?

jpitman2

Sticky air plate? Vaccuum leak? Have'nt heard this one before on a CIS. Are your fuel pressures OK? Air cleaner element OK? Is the idle OK? DOes it behave ok if you open the throttle less quickly?
jp 83 Euro S AT 52k

tailpipe

sounds like a vacuum leak to me prolly been there for awhile and somone adjusted to compensate for it and now its gotten bigger

Fabio421

Air plate? I'm assuming you are talking about the one at the fuel distributor. It seems to be ok. I was going to pull the fuel dist. and take it apart to see if I can find anything wrong in there, but I wanted to ask around here first before doing that.

I doubt it's a vacuum leak. I can lower the idle all the way down to 500 rpm and the car will run. Usually thats not possible with a vacuum leak.

Air cleaner is new

Idle is fine

I don't know if the fuel pressure is OK or not. I bought a CIS test kit and it doesn't have the proper fittings in it for the car.

It doesn't stall if you open the throttle less quickly

GlenL

The fuel distributor is a complex animal. Don't dig into it unless you're sure.

Has this come on slowly or abruptly? Any recent work?

Stalling when you open the throttle is because the mixture is going too lean to burn.

Check all the vacuum lines for leaks and loose ends. That investigation is easy and may fix your problem. And run some fuel system cleaner through it. I like Techron and SeaFoam. That'd be easier still.

Fabio421

I am very sure that I don't have a vacuum leak. The recent history is this:

The car hasn't been driven much at all for the last few years. The car ran fine when I did drive it on short test runs around the neighborhood. I put a bottle of techron in the car and drove it a few miles. The car started to lose power and wouldn't rev above 1500 rpm. It would run perfect below 1500RPM. So I ended up driving it home below 1500RPM. Thank you V8 torque.

I pulled the filter and replaced ( although it was new and clean ), I pulled all of the injector lines and blew them out with shop air, I pulled all the injectors and cleaned them in carb cleaner, I ran a little carb cleaner through each injector with pressurized air and they all sprayed fine. I resealed the injectors and put everything back together.

The car started and idled fine but it seemed to run rich. It had always run rich but now it was worse. I adjusted the mixture screw slightly to try to get it closer to where it needed to be. I took the car for a test drive and noticed that it would stall in between shifts. This manifests itself as a "lugging down" because since the car is in gear, it will restart immediatly. Similar to push starting a car.

I ordered a CIS test kit from a 928 vendor so I could verify my control pressure. It arrived but it doesn't have the correct fittings so I can't test pressure yet. I removed the fittings from the inlet and outlet to the fuel distributor thinking that they may be clogged. There weren't any screens in the fittings. A previous owner must have removed the screen. I disassembled the WUR and it seemed OK. Theres really not alot to it. It had a screen on of the ports. It was pretty clean, it just had a couple small pieces of debris. I cleaned it out and reassembled.

The problem remains. I have tried adjusting the mixture screw all over the place to see if that would make a difference and it doesn't, although it seems that the car is not running as rich anymore.

I've read the Bosch book regarding CIS and I'm thinking that my control plunger may be dragging. Disassembling the CIS fuel distributor is my next step but so many people here are scared of it, I thought I should at least ask around before doing that. Maybe I am missing something simple. The only step I can think of to take before disassembly is verification of the control pressure. I'll just need to source some fittings.

Any other ideas? I'm not scared of the fuel distributor. I've rebuilt alot of Bosche mechanical fuel pumps and injectors in my life. From the diagrams, this one appears to be pretty simple. My only concern is finding a rebuild kit that has all of the replaceable parts. The copper gasket seems to be hard to get. Does anyone have a source for this?

GlenL

I've done the fuel dist and it's complicated. It worked the first time for me but some guys have had issues. Replacement parts? I just cleaned it and put it all back. Used Indianhead Shellac to seal the copper plate. It's functional and not just a gasket.

The adjustment screw is very touchy. "all over the place" concerns me. I've tweaked it on a dyno and know that small movements, like 5 and 10 degrees, make a big difference.Very unlikely that's set at the right spot.

No filter on the inlet adapter? That's odd. It's hidden inside a double-male connector.

Is that the fuel filter that you replaced?

You need to get the mixture screw back into place. Could be a sticky plunger inside the distributor involved. Work the airplate and see. So here's my advice:

Work the airplate and see if it's sticky. Maybe you'll loosen it up
Confirm the adjustment screw is set right. Some guys say they can do this by smell and ear. I like hard numbers. I've thought about putting in a wide-band O2 sensor. You sound ambitious, maybe do that.
Open and clean the WUR.
Check operation of the air bypass valve by removing and plugging the vacuum line to it.
Use a timing light to verify correct distributor operation and steady ignition.
Check your "green wire" for abrasions and make sure it's routed on top of the bundle and away from the block.
Leave the fuel distributor until last.

Dennis Wilson

Sounds like the vacuum lines to the distributor advance unit could be reversed. May want to check the diagrams in the WSM to confirm.

Dennis

Mike Simard

Do you mean the round washer gaskets? The dist itself has a sheet but it's not a replaceable gasket.

I'll be glad to help out if you decide to dive in and rebuild it which would be the thing to do IMO. There are some things to discuss such as sealing and o-rings and little filter thingies. I need to clear these tidbits from my brain and make room for new stuff!
You could also need to address the WUR, it could possibly have something to do with your current issue because it handles control pressure.

Also, I have fittings and a bunch of o-rings that I sourced for these, everything except for one which is an oddball. Do you live near Daytona Beach? I might be there soon, for spring break!

Fabio421

Spring break? I thought that was last week? I live about two hours from Daytona. In central FL terms, thats pretty close. LOL

Regarding the fittings. I think the easiest thing to do would be to source fittings that would replace the male/male fittings in the WUR and the Distributor with a JIC on one end. I think the fittings going into the dist and WUR may be a standars metric pipe thread. I haven't verified yet. Working now, will have to do it later. If you have this info, please pass it on.

That metal sheet is what I was refering to. I have seen some call it a gasket and others call it a diaphram. I would assume that it is available somewhere. Aren't there places that rebuild these distributors? I used to source alot of my Bosch fuel components from a place is SoCal called Moparts. If I can get a Bosch part number off of the distributor I think they could probably get any parts for it that are available.

Fabio421

I've already done some of whats on your list but I'll check the rest.

Thanks

Will do.

Mike Simard

I don't know what those threads are. If you buy a gage kit from JC Whitney it has them and they fit.

Here's a reputable guy who rebuilds them:
http://www.cisflowtech.com/

jpitman2

I suggest back to basics - get the pressure tester working and verify system is 75psi, hot control no more than 45-ish, and the delivery rate is ok (1360ml/30secs). If it starts, cold control sounds ok, but hot control could do what you are seeing. Any of these wrong can give you a lean condition. With pressures unkown you are working in the dark. I have heard of some with CIS cars that have sat idle for long periods loading the gas tank with Berrymans, bridging the pump relay and letting it run for long periods to dissolve gunk and carry it to the filter....When I changed my tank and the fuel lines, I bridged the pump for 10 mins to leak test it (found one), and after that it fired first try.

When my WUR clogged, sitting idling seemed OK, but driving lifted the temp enough to produce a control of 60psi, and it wouldnt get past 15-20mph, on a gentle throttle. I recently bought a used WUR off ebay Germany, and cleaned it up. I could blow air through the inlet both ways, but I could NOT see through the hole. When I picked out the gauze filters I found there were FIVE layers of them!!!
jp 83 Euro S AT 52k.

PorKen

Tired or missing vacuum limiter?

tailpipe

the last fuel dis I took apart was doing the same sort of things it would rev to about 2500 rpm then bog after taking the dis apart I found the pots in the dis were full of debris not allowing the diafram to open completly sounds like thats what your dealing with good luck you can do it prolly don't need any new parts except new o rings