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CIS WUR and Fuel Distributor -rebuild because of age?

Both my WUR and Fuel Distributor checked out on pressures and the FD had equal volume on all injectors.

My question is does the performance of the WUR and FD degrade over time and miles? Or to put it another way, do they either work or not, or is there a benefit to sending them in for a rebuild and if so any recommendations on rebuilders?

Car is a '77

Thanks,
Rutager
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Old 12-30-2016, 05:20 PM
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I'll probably get flamed for this by others, but I see no reason to rebuild if it's functioning within spec. The system is very robust.
Old 12-30-2016, 06:56 PM
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By all means leave it alone. Sufficient unto the day and all that. If it is working you can't make it better. So you say it is like bearings - replace them so the new ones have many good miles on them rather than an unknown continuing life? Well, bearing failure is often catastrophic. CIS failures tend to be incremental, and can be chased down one by one. If pressures go off, the WUR can be adjusted - it is basically fairly simple compared with the FD. Resealing the FD after opening it up has caused many much gnashing of teeth.
Old 12-30-2016, 08:08 PM
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Old 12-30-2016, 10:01 PM
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CIS components degrade with age. The degradation is caused not so much by age as it is by contaminants and corrosion (which introduces contaminants). The non-Lambda fuel distributor is purely a mechanical device so the degradation slowly occludes the tiny passages causing issue. The WUR is both mechanical and electrical and can suffer from the same occlusions as well as electrical component degradation. At some point the system degrades to the point where fuel pressures and volumes reach levels that are close to being out of spec. That is where you first see issues. At that point I would clean everything. Change the filter, pull the lines, flush and clean everything including the fuel tank. Maintenance buys you time. Once the system is out of spec the components need to be rebuilt and, of course, everything must be flushed and cleaned. I am not a proponent of adjusting the WUR to compensate for a problem - fix the problem.
The vast majority of CIS issues we see could be prevented or at least offset by cleaning and maintenance. Keep the filter changed, inspect and clean the WUR screen, replace old dirty injectors with new, and drop the fuel tank for a full clean out. How often this needs to be done depends on how often the car is driven. The less you drive the car the more frequently you need to maintain the fuel system as it sits and rusts while the water separated out of the gasoline.
We handle rebuilds for a lot of FDs and WURs, it is unbelievable the shape some are in and the car still runs.
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Old 12-31-2016, 06:57 AM
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Rutager,
If you have the one CIS system that still works well...............don't fix it.

regards,
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Old 12-31-2016, 06:59 AM
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Quote:
Originally Posted by al lkosmal View Post
Rutager,
If you have the one CIS system that still works well...............don't fix it.

regards,
al
That's funny Al! Been following your itb threads, great upgrade, just a bit rich for me now- I do think it won't be long that the cost to refurb CIS will equal EFI.

My system basically runs fine, I put a new air box and replaced virtually all the gaskets, seal and hoses that I could this spring hoping for a perfect running car, but not there yet. My idle doesn't drop when oil cap is removed, acceleration is very flat from idle to 2500rpm and holding a steady speed can have a very, very slight bucking sensation.

Since the WUR and FD are the heavy hitters in the system, I thought I would get some opinions on if they needed a rebuild every thirty years or so! Car does see regular use and non-ethanol fuel most of the season and during storage.

Rutager
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Old 12-31-2016, 10:29 AM
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Quote:
Originally Posted by fanaudical View Post
I'll probably get flamed for this by others, but I see no reason to rebuild if it's functioning within spec. The system is very robust.
Agreed. Maybe pull injectors and clean / replace o-rings on them, but if the FD & WUR are working leave sleeping dogs lie...
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Old 12-31-2016, 10:47 AM
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PS,
Run only clear gas, keep the fuel filter and swirl pot screen clean and when you park for any length of time - especially in winter - keep the tank full. A splash of Stabil never hurt either.
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Old 12-31-2016, 10:49 AM
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concur, not to mention the cost of not fixing it, to have them rebuilt to spec is what say $1500?

A check on the FD, is it should not flow any fuel with the injectors removed, the fuel pump hotwired, and the air flow plate at rest.

WUR is easy to do, anyone can do that if the VAC diaphragm is good. The FD I have not yet had success with and the last one I had rebuilt (by a pro) failed the test above. So doing nothing if everything is okay is sometimes a very wise option.
Old 01-01-2017, 01:34 PM
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I agree with brain, but, I also agree that if tested and all tests are good, it idles smooth and runs good, I would just run some cleaner every now and then and leave it alone. just make sure all the rubber is good so no vacuum leaks,.

I would also do injector volume tests at a simulated idle, you have to run this one for a long time so connect a battery charger and I would test at WOT.
the more fuel you have to compare the better.

I personally like the 76-79 systems the best.
make sure the WUR holds vacuum
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Old 01-03-2017, 04:22 AM
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Very wise advices........

Quote:
Originally Posted by fanaudical View Post
I'll probably get flamed for this by others, but I see no reason to rebuild if it's functioning within spec. The system is very robust.
Jim,

No you won't and completely agree with your advice.

Quote:
Originally Posted by Walt Fricke View Post
By all means leave it alone. Sufficient unto the day and all that. If it is working you can't make it better. So you say it is like bearings - replace them so the new ones have many good miles on them rather than an unknown continuing life? Well, bearing failure is often catastrophic. CIS failures tend to be incremental, and can be chased down one by one. If pressures go off, the WUR can be adjusted - it is basically fairly simple compared with the FD. Resealing the FD after opening it up has caused many much gnashing of teeth.
Walt,

A very logical advice why you should not worry fixing or correcting something that is not causing you a problem.

Quote:
Originally Posted by timmy2 View Post
If it isn't broken, don't fix it.
Dennis,

Yes, completely agree with you. But others in this line of business might think otherwise.

Tony
Old 01-03-2017, 07:12 AM
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No one thinks you should rebuild a component that is performing within spec, especially as these cars have been out of warranty for 30 years. Maintenance is another issue; CIS is a commonly neglected system. A little maintenance goes a long way.
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Old 01-03-2017, 10:11 AM
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Steve W says run Marine Stabil in every tank. Preserve, don't rebuild.
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CIS WUR and Fuel Distributor -rebuild because of age?

Bump to a good thread topic.

I just completed a full fuel line replacement on our 78 SC all six main lines( thanks to Len and his fantastic lines). Replaced the fuel filter before the car went down for a full suspension refresh and still currently down after 24 months. Yeah, that slippery slope deal.....

Anyway, I also replaced the accumulator and have a new filter in stand-by. So I was wondering if I should replace the installed filter (24 months ago)in the car or should I replace it as well? I'm also looking to install a small inline fuel strainer between the tank and pump as well.

But I also have a couple questions regarding injectors and the above mentioned WUR "screen". The original set of injectors are currently running with 260K and I was looking into swapping with new ones(thoughts?) and is it a good idea to clean the screen on the WUR(no idea where that is, internally I assume). The car ran fine before I parked it for the suspension deal and all the fuel has been removed from what I have worked on, however I know there is residual fuel in the system.

Thoughts and suggestions?
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Old 07-16-2017, 08:36 AM
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Injectors with 260K miles on them were shot a long time ago. I'd be surprised if they weren't changed out sometime along the way. You can clean them which results in clean worn out injectors.
The screen in the WUR is on the intake side. Just remove the fuel line and look inside and you will see it. I'd clean the tank as well, no need in plumbing all new components only to run bad gas and contaminants through the system.
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Old 07-16-2017, 07:13 PM
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Quote:
Originally Posted by bugstrider View Post
Bump to a good thread topic.


Anyway, I also replaced the accumulator and have a new filter in stand-by. So I was wondering if I should replace the installed filter (24 months ago)in the car or should I replace it as well? I'm also looking to install a small inline fuel strainer between the tank and pump as well.


Thoughts and suggestions?
Who knows how clean everything is that you just put in. I'd run it with the old filter, then put a new one on in a week. Or, if it's on standby, put the new one in. What's $20 at this point in the journey?
Old 07-16-2017, 07:36 PM
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On my old SC I sent the injectors in for cleaning, I had around 170,000 or so miles on them. The shop called me and said they were all shot. They recommended I replace rather than rebuild.

So, I installed six new CIS injectors. Couldn't tell any difference.
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Old 07-16-2017, 07:38 PM
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And, oh yeah, if the CIS works don't mess with it.

Frankly I love CIS. I had it in my first car, Audi 4000, in my 924s, and now in the 911 - and to me it's a great system that's trouble free once it's set up. Don't mess with it. The only thing besides maintaining it with clean filters is not having it sit. CIS hates to sit in my experience (like anymore than 6 months).
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CIS WUR and Fuel Distributor -rebuild because of age?

Quote:
Originally Posted by RarlyL8 View Post
Injectors with 260K miles on them were shot a long time ago. I'd be surprised if they weren't changed out sometime along the way. You can clean them which results in clean worn out injectors.
The screen in the WUR is on the intake side. Just remove the fuel line and look inside and you will see it. I'd clean the tank as well, no need in plumbing all new components only to run bad gas and contaminants through the system.


Kinda what I thought on the lifespan, however I never saw any indication of them being replaced. Seals yes, and I installed new intake sleeves when I addressed the "triangle". I inquired about new injectors to a Porsche buddy/shop owner and he said notes to worry. It's always been in the back of my thoughts. These things look original.

The WUR is all exposed due to the line replacement and I did drain the old fuel from the tank. I'll take a look at the fuel one like you mention, I'll see what I can gleen. That's also why I was also looking into a "pre" pump inline filter as well.

Thanks


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