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CIS Rebuild

 
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Ozzie  



Joined: 12 Mar 2005
Posts: 4448
Location: Townsville, Qld. Australia

PostPosted: Thu May 29, 2014 2:54 pm    Post subject: CIS Rebuild Reply with quote

Erratic Idle, Injectors spraying without the engine running, unequal flow from injectors usually means an overhaul is required.
Kits are available to match the part number on the CIS or if you prefer, get the parts individually.
I bought a kit and it comes with different seals for variants and not all are used.
A new metal diaphragm is also included in a kit.

So you have it on the bench and ready to start.


1. remove ‘O’ ring
2. straighten lock tab and undo 19mm nut
3. check orientation of notch in piston housing
4. undo 8 screws
5. separate gently the two halves,

*do not twist, use any levers or damage the mating surfaces, a few light taps on the outside with a hammer should be all that is needed.

You should now be at this stage.



Pull off the centre cylinder and remove the piston if it has not already been removed.



There are 6 ‘O’ rings here to be replaced, check the small fuel filter and remove and clean if necessary.
Check movement of piston in the cylinder and very lightly sand if necessary.


There is an ‘O’ ring in the base, a bit tricky this one.


And one final ‘O’ ring in the pressure relief valve (may be different for USA models)
Shims may be needed to adjust system pressure later.
System pressure should be between 65-75 psi.


Insert the piston back in the top section, using plenty of lube, wd40 or oil, aligning the mark with one of the outlets.
Fit the new diaphragm and reassemble.


There you have it, a lot simpler to do than expected; on a scale of 1-10 I’d give it a 5.
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Porsche 924 1984 (UK import) NA
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Montego Black on black/red
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Ozzie  



Joined: 12 Mar 2005
Posts: 4448
Location: Townsville, Qld. Australia

PostPosted: Thu May 29, 2014 3:10 pm    Post subject: Reply with quote

Result after setting the a/f mix -
smooth idle, easy start, no misfire, pulls well.
I think this is the best it has run since I bought it.
Still have a hot start problem but can live with that.
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Porsche 924 1984 (UK import) NA
Its AUTO and its BLACK
Montego Black on black/red
Engineer of Electro/Mechanical Systems Maintenance
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Rasta Monsta  



Joined: 12 Jul 2006
Posts: 11723
Location: PacNW

PostPosted: Fri May 30, 2014 12:50 am    Post subject: Reply with quote

Wow, good work. I haven't tried it, but I understand these can be a bear to reseal.
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Ozzie  



Joined: 12 Mar 2005
Posts: 4448
Location: Townsville, Qld. Australia

PostPosted: Fri May 30, 2014 6:54 am    Post subject: Reply with quote

maybe a fluke but haven't had any problems.
Make sure everything is clean especially the mating surfaces.
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Montego Black on black/red
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musicalannette  



Joined: 21 Feb 2012
Posts: 413
Location: UK

PostPosted: Sat May 31, 2014 10:41 pm    Post subject: Reply with quote

Would you recommend scotchbrite as a surface cleaner if its needed?
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Ozzie  



Joined: 12 Mar 2005
Posts: 4448
Location: Townsville, Qld. Australia

PostPosted: Sun Jun 01, 2014 9:33 pm    Post subject: Reply with quote

probably 1200 wet and dry.
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Montego Black on black/red
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MikeJinCO  



Joined: 08 Jun 2010
Posts: 1227
Location: Maysville, Colorado

PostPosted: Mon Jun 02, 2014 11:26 pm    Post subject: Reply with quote

If you're going to use 1200 paper. Way back when we had to repair industrial piston type air compressor valves(called reed valves I think) the technique was to put the paper on a sheet of plate glass. then take the valve part with a little oil on it and sand it using a figure 8 motion. The figure 8 motion tends to equalize all the little natural pressure variations from pushing it around. I'd practice first using some Prussian Blue on a chunk of steel. It was pretty tricky to do correctly, but got a surface better than a surface grinder.

This really dates me.
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'67 MG Midget Dp
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Ozzie  



Joined: 12 Mar 2005
Posts: 4448
Location: Townsville, Qld. Australia

PostPosted: Tue Jun 03, 2014 9:44 am    Post subject: Reply with quote

Yes- definitely the best way
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Its AUTO and its BLACK
Montego Black on black/red
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