CIS question - cold start valve test

[Alan L]

Originally Posted by tirwin

Tony,

Just a curiosity question... any idea what is exactly failing on those CSVs? Have you tried dissecting one to see if you can determine what is happening?

I did cut one (failed) open once. I posted a pic on Pelican - either in the 911 tech or 930 forum. About 15 yrs ago. It should come up in a search.
Alan

[jimmyjimmy]

i put 12V on it and squirt carb cleaner in it to see if it opens.
mine was faulty too ,left it 2-3 days in carb cleaner and it worked again.

[E Sully]

Originally Posted by Alan L

I did cut one (failed) open once. I posted a pic on Pelican - either in the 911 tech or 930 forum. About 15 yrs ago. It should come up in a search.
Alan

Here you go. Simple device, electromagnet pulls pin back and allows flow.

[Alan L]

Thats it. Well done. In my case the piston had some rust and was binding in the bore. Nothing I did would budge it.
Alan

[sunlion]

I’ve got 2 CSV, both click with 12v directly from the battery. I’ve checked all my connectors from the starter to the TTS. There is continuity and voltage. My TTS is bad so I’m grounding the red/Blk wire to the TTS. It goes/comes directly from the factory plug for the CSV. Neither valve is squirting fuel but both are clicking. Just checked resistance and both read zero meaning no resistance. I don’t understand why it would click, meaning it energizes but yet act like it’s open (no resistance between the terminals.) Must be a special crud situation inside. Thoughts? Ravi.

[Alan L]

Zero ohms is different to a no circuit. You have a circuit - thats why it clicks.
Alan

[sunlion]

Right. Perhaps I’m missing how is the zero ohms explained. Per specs above, should be around 4 but not infinity and not zero. There should be some resistance between the terminals, 4 ohms. Infinite ohms would mean something has shorted out breaking contact and zero means there a short making contact all the time. Weird that both my CSVs are the same. I plan to let them soak longer in carb cleaner. Then check after a few days. Trying to understand. Thanks fellas.

[Alan L]

I have a spare good one.
Will check
it is not a heating circuit. It is an electromagnetic circuit. Heating circuit relies on resistance. In the case of an electromanetic coil, less is best.
Alan
Edit 4 ohms

[Alan L]

If it has a circuit and not clicking it is jammed. If it has not had fuel thru it before, carb cleaner prob won't help. My faulty one had a rust spot inside.
Maybe worth trying to soak it in something else - like maybe citric acid.
Nothing to loose. But if it is stuck shut, nothing will enter from the bottom.

Alani

[Alan L]

The polarity matters to make the valve click.
My multi meter also read 0 ohms initially. I had to wait about 15 sec for it to find 4 ohms.
Whatever you use to try and free it you will need to pour down the bore.
If carb cleaner won't do it (only work if had old fuel in there likely) then something like CLR may help.
Not sure if you have same - takes out lime and rust.
Mild acid - oxalic I think.
Alan

[Alan L]

OK just re read, they are clicking. In which case they must be opening. Can you blow gas thru - compressor?
Alan

[Alan L]

There is a fine screen in top of them. May be blocked - if had fuel thru previously. Crud.
Alan

[sunlion]

Thanks Alan. Interesting on the resistance reading. Initially the 2 I have read 4
Ohms when pulled, but zero ohms after a few hours soak. I’ll do the air test now as they’ve been soaking overnight.

[E Sully]

Originally Posted by Alan L

There is a fine screen in top of them. May be blocked - if had fuel thru previously. Crud.
Alan

Yes, they can have some build up in them, and a fine screen filter as I posted in the sister thread. csv
I'd say to pull the filters before blowing air through to make sure not to damage the screen. I've checked for flow using the syringe and a piece of hose with 12v applied. I used a 3mm tap to pull the long skinny filter, and an 8/32 tap for the shorter thicker filter. I only lightly turned the taps in enough to get enough grip to pull them after soaking in WD40 and PB Blaster for a few days.




I've been able to free up 2 '86 fuel injectors and a CSV by soaking, tapping against a piece of wood, and applying 12v over a period of time. They still need a good 2 way flushing to clear them out after freeing the piston. The '86 injectors worked great after cleaning years back when I had that engine in my '73.

Continuity tests can be tricky sometimes. It can be difficult to get both leads from the meter in good contact with the terminals.

[sunlion]

I’m impressed you got those screens out intact.

[sunlion]

Ed, My CSVs are different than yours pictured. Mine have the fuel line on top and the electrical plug off to the side. But I can see a screen within the body.

[Alan L]

Try and pull the screen first, as Ed has described. May explain all.
You could then try your test with the screen out. Then you will know where the problem is.
Alan

[E Sully]

There were a few different CSV's. Mine came with the one year only 73.5 CSV, 911 606 101 00.
There was another, which I have one of, for the later 2.7 CIS, 911 606 101 02.
Then a CSV for the 3 liter CIS, 911 606 107 01.

[Jay Laifman]

Originally Posted by Alan L

If you get the 12V the wrong way round it won't hurt it, but it won't open either. The magnetic field is directional dependant on current flow direction.
Alan

Does that mean if you flip the connector 180* when putting it on, it won't work? I do not recall the connectors having any shape or rib that forces them to go in only one way (on my 73.5).

[E Sully]

I have checked this and it will still open with polarity either way.