CIS injectors injecting continuously
 

OK, I got the ingine in and mostly installed without bugging the board much, but now I have questions:
I bought a 1974 911 2.7 with CIS with a wrecked engine, almost all parts included but the ignition and CIS in pieces. These have been re-assembled in a fashion that appears to match the diagrams (here and at the enormously helpful CIS primer http://members.rennlist.com/jimwms/CIS/CIShome.html).
But, when I turned on power to the pump, expecting to check the spray pattern while fiddling with the air plate, all injectors started spraying continuously. This richness does not seem like a cold start valve problem, so what would be the next adjustment? Moving the plate does not affect the pressure.

Thanks, and I have already looked for obviously titled threads in the archives.

Perhaps the fuel distributor metering valve is stuck?
-Chris

CIS....Continuous. Injection. System.

Yes... continuous injection is correct vs. sequential fuel injection.

targa911: Sigh. Yes CIS = Continuous Injection. He knows that. CIS squirts when the air meter is moved up by air - not when the just the fuel pump is running i.e. the fuel distributor only supplies fuel to the injectors when the motor is running.
kellzey: CIS is not the "flip side" of sequential injection. Sequential is just a flavor of Electronic Fuel Injection
-Chris

Dr. No,

First of all...'sit down'...(sorry no caged spider available ;) )

I have the same '74 motor...the idea is that these spray continously from the moment power is applied to the fuel pump...air sensor plate meters the volume delivered depending upon condition...this is normal operation.

Btw, sorry Crab Key was destroyed...I was just doing my job...;)
Ryan (007)
:cool:

i bet chris is right. the injectors dont spray when the engine is not running. you need the pillow of air to hold up the sensor plate. take the fuel dist off partially and peek under it, is it stuck. a good indication, is also; when you lift the plate manually, do you feel any resistance? no resistance like a perfectly balanced balance (that was an awkward sentence, sorry) usually indicates a stuck control plunger. even zilcho fuel pressure, there would be a tiny bit of resistance. but you already proved there is fuel press.

cliff

Ack...my bad...Cris is right...they only should flow while the engine is running and the air sensor plate actively metering a fuel volume. Started to sound like maybe a stuck comtrol plunger...need to think a moment here...
Ryan

I did some work on a '74 CIS that had been sitting for a 10 years. The fuel distributor was gunked up enough that air wouldn't lift the plate but I could lift it by hand. To start the car I needed to lift the play by hand but after running it for a couple of days it worked fine.
Thinking out loud...
If your fuel distributor is stuck open I would think that the air meter plate would move with no resistance at all and then hit the "pill" that meters the fuel. If the "pill" is really stuck, the plate would stop right there. If the pill is just gunked up, you would be able to move the plate up further with some "gummy" resistance.
-Chris

I'd also start at the fuel distributor.

I'm with Chris on the stuck control plunger...it's the only think that would allow fuel to flow to the injectors...should be closed without engine running, but yours is apparently open. It's possible that the pivot lever between the air sensor plate and the plunger is having no bearing because the plunger is already stuck 'open' or 'up'....so movement of the plate has no impact, matching your symptoms.
Ryan

try just cranking the adjuster counterclockwise until they just stop spraying. if the piston was stuck you would feel no pressure on the sensor plate arm when you lift it, or at least some freeplay. the arm lifts the piston.

Chris: sigh, that was tongue in cheek. I know nothing about CIS. I leave that to you experts. I've got my hands full with my MFI.

Sorry. I must be grouchy today.
-Chris

I understand...it's cool.

Thank you all for your replies.
Yes the plate bounces up and down with no resistance or effect on the spray.
Is there a way to free the piston without taking the whole fuel distributor apart? I have "spare" CIS unit from a Rabbit I will dissect later for more data (it also bounces freely, but there is no fuel pressure to deal with).


And, yeah, I didn't thing 'continuous" meant filling up a couple of cyliders before applying spark.

You can blow compressed air into the top, center port to loosen the stuck plunger. You'll probably want to remove the fuel distributor from the sensor plate housing first. Be sure to catch the plunger so it doesn't go flying. I wouldn't recommend disassembling the fuel distributor unless completely necessary. I've done it, but it was a huge pain to get it sealed up properly afterwards.

-Rob
1980sc

I think I'll try the compressed air route. The fuel distributor can be removed from the air box without dissasembly. Here are pictures from the 4-hole rabbit version. http://forums.pelicanparts.com/uploa...1079492183.jpg http://forums.pelicanparts.com/uploa...1079492198.jpg

And by the way, that was not really Crab Key--it was a decoy. Your day will come, Bond...

But...I saw you disappear into the radioactive vat...?! Curses...
Ryan

Two hours of busted knuckles, BP Blaster, and finally a drill for the last of the three screws the FD is separated from the rest of the thing. The plunger is apparently welded in there--it won't even turn in place. Next--new/used fuel dist. or disassemble this one. Any advice on that job?http://forums.pelicanparts.com/uploa...1079539450.jpg

Here's a pic of when I rebuilt mine. The plunger was stuck on this one too, but it was before I knew about the compressed air method. You can do it if you have the patience, or you can find a used distributor for around $200.

http://forums.pelicanparts.com/uploa...1079540276.jpg

-Rob
1980sc

You're not the real Dr. NO. The real Dr. No always wore gloves.

Blue nitrile from Harbor Fright (sic) or purple nitrile from work.
Neither provides much cushion when the rachet slips.....
And here is my caged spider:http://forums.pelicanparts.com/uploa...1079541748.jpg

sometimes you can get a grip on the end tit with some needlenose visegrips and get it to move.

dr, no. it will move. you gotta use carb spray. pb blaster is way to thick to get inbetween the tight clearances. think about it, gasoline cant get through. no way pb will even stand a chance. you may need a new FD anyways, so time to get medival on your existing one. at least that was my philosophy. needlenose pliers and carb spray. spray the bastard down, and grab the tip with the pliers and just start push/pulling it to get it to move. you will barely do anything at first, and then you kinda build up momentum. more spray and repeat. the smart money is on you, not the damn plunger. once it pops out, it may fly. dont let it hit the ground. you efforts would be wasted if you hit hit the flying control plunger against anything hard. like i said, the machine tolerance is amazing!

you can get new screws to hold it down easy. and they dont need to be so damn tight. they only need to hold the FD down, and there are three of them!

Are you allowed to use t*t on this board?

If you have an understanding wife or significant other maybe putting it in a hot oven (450) for about a half hour will cause the metal to expand enought to allow you to remove the plunger.

Carb cleaner use to work fine for me. Just don't reach into the cleaner if you have scrapes or cuts on your hand.

Properly, it should be spelled "teat" and pronounced "tit".
When I said welded, I meant welded. Hemostat, needle nose, Visegrip, nothing will move it at all. The whole FD is now sitting in a can of Chem-Dip. Maybe for a week.

"Underneath the mango tree..."

Sorry...didn't have anything in particular to add...just that...No will understand...

my honey and me

I understand.................

Mission accomplished!
Nine days in the chem-dip bucket, sprayed it off (I hate the way that stuff smells), grabbed the teat with the needle-nose (kinky) and it resisted a moment, and now moves freely. All reassembled and re-installed and the injectors spray only when the plate moves.
But now, no spark.
New topic....

Well, now that you have learned patience ...

Less brute force will be needed for the CDI system, but cutting and crimping will be needed for the bench test ...

http://forums.pelicanparts.com/porsche-911-technical-forum/155489-72-911-t-all-sudden-no-spark.html

no spark is harder.

Persist it will pop out
 

Just in case this helps, reviving an old thread.

I had the same problem, gas pouring into each cylinder when the ignition was on - CIS was sending fuel continuously. Culprit was a stuck fuel distributer plunger, which was as result of vanished fuel because car was sitting around for a couple of years during restoration.

I ended up taking the whole flapper and distributer off (didn't like the look of the tree screws), I used lots of carb cleaner on the plunger and then compressed air into the centre inlet on top of distributer to free the plunger with the distributer right way up on rags so that when plunger released it popped onto rags. It took some time and effort, and now running beautifully. Needless to say very happy. Thanks to this board and Pelicanites.

Wow, nice revival!

Great timing for me with the exact same issue. Wish I'd found this thread 8 weeks ago!