CIS help anyone?!?!

[air-cool-me]

I need to get my 79sc in tip top shape before i turbocharge it.

The problem is recently I have been having some starting issues.


Starting is a little weird, first it takes a bit to crank over... then it feels like it runs on only a few cylinders.
It sputters and shakes down at 300rpm for a second then if i tap the gas it starts to climb slowly. Once its been coughing for about 5 seconds it comes to life.

it feels like someone throws a switch and the rest of the cylinders come to life.

then if i don’t set it gently down at 900rpm to idle... it will fall down to 300 then shoot up to 1200 then fall again.. then shoot up..
Occasionally it doesn’t recover from a fall and dies.. but then starts right up!

after about one minute it just has a hunting idle..


when its hot none of these symptoms are present.

Looking at the CIS trouble charts... I am guessing vacuum leak?

if thats it, im gona find it tommarow!

[afterburn 549]

perhaps warm up regulater.....if your gonna turbo it you will probly end up throwing most of that crap away....................................

[slater]

I don't know enough to answer your problem, but incase you don't already have them here are a couple of good links that helped me.
http://members.rennlist.com/jimwms/CIS/CIShome.html
http://www.phat-gti.com/downloads/boschtech-12d.pdf

Good luck!

[air-cool-me]

perhaps warm up regulater.....if your gonna turbo it you will probly end up throwing most of that crap away....................................

thats the idea.. .. i might just strip the motor down to bare min in 24hours

[afterburn 549]

did not mean to say anything wrong......just pointing out why wast time and $$ if your gonna do away with that stuff anyway??

[clevy70911T]

I'm pretty new to CIS, but after tackling a number of problems I can say that you have to check many things and rule out things like
system pressure, cold pressure, warm fuel pressure, vaccuum leaks, aux air reg working correctly, mixture. I used the above links to learn and start going through everything one at a time to eliminate future problems. Also due searches on Pelican for the various component tests.

[David]

If you're going to stay with CIS for any length of time, go ahead and buy some CIS gauges (about $100) and check your cold fuel pressure. It sounds like a WUR.

[stlrj]

Seems like your probem has to do with your CIS not being able to maintain residual pressure so when you shut it down, bubbles (vapor lock) form in the lines, so the next time you try to start ...you know the rest.

Cheers,

Joe

[air-cool-me]

i was going to go check things out today... but 4 inches of snow changed my mind

[vizail]

Check the Fuel Accumulator too..!

Vic

[makaio]

You need a fuel pressure test to really tell you what is wrong. But it sounds like a vacuum leak to me.

[azasadny]

Check all vacuum lines, fuel lines, WUR, CSV, wiring. It takes alot of detective work, but once you check everything, you'll be a "CIS expert" and will be able to troubleshoot quickly. Don't start buying parts until you go through everything one-at-a-time as it gets expensive to replace everything (ask me how I know)!! Also check the gap on your spark plugs and check the plug wires.

[jess p]

Take a 3mm alen wrench, and insert it into the fuel distributor
co adjusting nut. Turn clockwise one-fifth of a turn. That should
slove your start up problems.



76 911
81 911 SC
66 912 V8
70 914 project
66 912 2.2

[air-cool-me]

um... why?

[Mike Kast]

The amount of all over the place opinions offered about what the problem may be seems about as helpful as getting nothing at all. I guess that shows what a confusing Pain in the A$$ the CIS system is.
When I had CIS problems it turned out to be a sediment issue. It is hard to say where all the sediment came from but it came. Souk and Zeek led me in the right direction in the clean up. If there is a sediment problem the cure starts in the gas tank.
My tank had plenty of sediment but how did it get past the fuel filter? I don't know if it did. but on the engine side of the filter things were nasty too. I ran lots of injector cleaner through the system and the car would run good. What I think that did was let loose rust and goo that had been fixed for years and it clogged things up.... It was a mess. I felt like I was chasing ghosts.
If you think it is possible you have a sediment problem one quick test might be to remove the Warm Up Regulator and check the screen. If it looks clear then that would mean the screen is clean I found out the screen in my in my WUR was clogged when I was replacing it with a new one. I was soon thereafter scolded by the PO because he had changed the WUR 2 years earlier when he did the rebuild. I'm sure the not so old one was fine if I had just cleaned the screen. It was the same with the injectors, but they were clogged so I changed them.
I cleaned out every line, part and fitting with lacquer thinner. I fought the problem for a year. It seems to have been worth it but I thought it would never end. I haven't had any CIS issues since last winter so I'm thinking I won, for now...

[jess p]

sediment that eventually finds it's way into the fuel distributor
will cause the plunger to stick. this problem will present itself
in all phases of the rpm range. Oftentimes, the control pressure
regulator will fall slightly out of spec. This is compensated
by a slight adjustment of the co screw. This simply causes the
plunger to move up or down which in effect causes more
fuel to flow to the injectors or a decrease in fuel flow to
the injectors, without the vain moving. The fuel distributor virtually never fails. The weak link in cis are the fuel pumps which always require a minimum of 65 psi control pressure as output.
The job of the control pressure regulator is to oppose the
control pressure flow based on engine operating temp
initially. The control pressure regulator is the second weak link
in cis. A clean fuel supply is essential as well.

76 911
81 911 sc
66 912 v8
66 912 2.2
70 914 project car