CIS Rant!

[Jay Laifman]

Ok, I may come back and recant all of this, especially since I've been a very long supporter of my 73.5 CIS, and tend to try to encourage people to not dump CIS for carbs. But, I'm in the middle of train wreck and I'm going to tell about it.

My 73.5 has been through three rebuilds and countless CIS changes for the last 4 years, and now the latest problem appears to be that the fuel distributor is bad. But, when we were trying to track down the source of my poor running, I personally brought it to Python who rebuilds fuel distrubutors to test it. They tested it and gave me this nice form showing it passed with flying colors. So, we IGNORED the FD during tracking all the problems, which lead to the third rebuild. Yet now it seems like it really is bad. This of course brings in to question Python's testing abilities - and of course since this is the test they run all their rebuilds through, this brings into question their rebuilds themselves!

So, of course, what to do? Break down and buy a rebuilt one from Bosch. But, guess what? No one has them! Not even Pelican. Had I known that after all the money I have spent on new CIS pistons and rebuilding the heads twice, that I'd end up with a part that is NLA, I'd have gone in such a different direction! A rip roaring 3.0, hot cams, hot pistons, hot PMOs and be done with it! But, NO! I had to love how my 73.5 CIS runs (or ran) and do tend towards originality.

My mechanic has a guy in Alabama who apparently can rebuild the fuel distributor, and do a good job. I don't know who this guy is.


As an aside, the original rebuild was to fix worn valve guides, which included a new clutch and P&Cs with Deves rings. The second rebuild by the same guy with help from another Porsche mechanic was because it wasn't running well, the new rings were not sealing, and it had a vibration at 2,300 rpm. The Deves rings were replaced by OEM and it was rebalanced. But, still it did not run right and the 2,300 rpm vibration was still there. I decided to take more into my own hands, and with the help of Pete Z. and Jim Williams, and Art Z, found that the WUR was dead, the cold start o-ring was the wrong one, the throttle body had been epoxied to the airbox, the fuel pressure was too high, the intake runner gaskets had been reused multiple times, and the airflow plate was not adjusted exactly right! I fixed all that, for a noticable but partial improvement. Thus, a third rebuild, now by a completely new mechanic. This third mechanic found that the clutch was bent, probably by a bad installation during the original rebuild and the head rebuild was a disaster: the exhaust valves were burnt and had not been replaced, the valve seat grinds were bad, and the valve guides were too long causing the valves to bottom out on the guides not the seats! So, the 2,300 rpm vibration has been fixed with the new clutch and the valves are much happier now. But, still not perfect, and thus back to the fuel distributor. Anyone want to trade an almost perfect 2.4 CIS engine for anything else?

[Paulporsche]

Sorry to hear about all your problems!

So what are your current symptoms and why do you suspect the FD?

[spuggy]

I got a 930 rebuild invoice with my car. Monty @ Redmond European sub-contracted the fuel head rebuild to an outfit called "Pacific Injection".

Imagine Auto modify 930 fuel heads, I'm sure they could rebuild a stock one. Others must be able to do it too.

Keep the faith, it'll all be worth it when you've got it sorted.

[patkeefe]

Imagine Auto did my SC fuel head...but it was a non stock application. I think they sent it out somewhere.
Pat

[john walker's workshop]

i think special t subs them to python. try www.fuelinjectioncorp.com

[Porsche-O-Phile]

At some point, someone is going to have to break down and pull the F.D.s apart and repair them. At the moment there are a lot of used ones floating around out there, but the day is fast approaching when someone is going to have to either develop a replacement or a solid method for rebuilding those distributors.

I like the authenticity of the CIS system myself, but I have to admit, the allure of the PMOs has great appeal. I hate to admit it, but the biggest reason I'm staying with CIS for now versus going carbs is because the PMOs are so damn expensive, not because I have any great love for the CIS system. I don't hate it and I'll certainly keep it when I finally do make the switch, but carbs are just so much simpler, easier, etc.

[JP911]

I have two unrelated thoughts.

1. What condition are the fuel injectors and all of the fuel lines in? Maybe the (some) of the injectors are clogged, and old fuel lines can get crimped or clogged as well.

2. 40mm PMOs would still work well with your setup, just not as "good" as with high comp carb pistons, hot cams, etc. While PMOs aren't cheap, neither are replacement CIS parts or the labor spent diagnosing, rebuilding, etc.

[Mysterytrain]

Have you tried these guys:
http://www.jaytanindustriesinc.com/PorscheFD.htm

[patkeefe]

Great link, Ron. Maybe someone has used one of these Jaytan FD's? Their prices are great.
Pat

[stlrj]

I had a bad injector that made me to buy a rebuilt FD...boy, did I feel stupid!

Joe

[Bobboloo]

Boy Jay I really feel for you. It hurts just reading your post.

It seems your problems stem more from incompetence than anything else so try not to take it out on the CIS.

I think you need to find someone qualified to troubleshoot your car/CIS.
Flow rate should be measured to the injectors before replacing the FD. Injectors should be checked for spray pattern.

I find it strange that Python would give the FD a thumbs up if it had a problem because after all they only make money repairing faulty ones.

How did you determine that the fuel distributor is faulty?

The sad truth is that there are mechanics and or repair shops that haven't a clue on how to troubleshoot a problem. They just start replacing parts at your expense. When replacing one part doesn't fix it they move on to the next. The reward for their incompetence is they make extra money selling you parts you didn't need.

I had my Mercedes in a shop once for what seemed like a fuel delivery problem. I told them that a fuel line had just been replaced and soon afterwards the problem started. They started replacing parts at my expense and when it still still didn't run right they announced it was the FD and it would be $2500 non-returnable. When I asked them what delivery rate measured as the guy had a blank look on his face and then said he didn't measure it. I asked what the pressures measured as. "Uh I didn't measure the pressure". I then told him to not touch the car anymore that a tow truck is on the way to come get it.

Long story short it was the "new" fuel line. I had even put it in writing that the problem started after the line was replaced when I dropped the car off. A measurement of delivery rate by a competent mechanic pinpointed the problem.

I wouldn't buy another FD unless you can be certain that it's faulty because you'll really be frustrated and p*ssed if replacing it doesn't fix your problem.

Has the ignition been properly tested for a clean bill of health? A faulty dizzy or intermitent electrical problem can make a car seem like it has a fuel problem.

Time to take a deep breath, step back and take your time to decide your next course of action.

[HarryD]

Jay,

Maybe you just do it your self. Check this thread: CIS fuel distributer cleanout w/pics

[SCWDP911]

sub'd. I hope you can get this sorted. I am awaiting someone to speak up about Jaytan Industries. That looks promising for future needs. Also, would someone post the contact info for the one in AL, as they are close? I wonder if that is the Jim guy that wrote a CIS book I saw on eBay recently. He is from AL I think...

[Gunter]

It sounds to me that the first two rebuilds were done by severe incompetents, really bad.
Sometimes the special rates offered by some "Mechanics" turn out to be an expensive nightmare.
I wonder why one would go back to the same place for another helping of a second rebuild?
Next, I agree that a shop speciallizing in 911's should be able to trace problems with a K-Jetronic CIS.
All the components can be tested individally and in conjunction with each other.
The problem here seems to be the people working on it, not the CIS itself.
Maybe someone can point out a "real" Porsche shop in your area?

[Jay Laifman]

Thanks for all the comments. In response to all, yes, the first shop which is one guy who works on lots of Italian high end cars and Porsches, must have been out of his league with this. In defense of the second guy, he was just helping the first guy get the engine back together on a short time frame, and didn't have anything to do with the heads, bent clutch or CIS - though he did mess up the tranmission rebuild and had to redo that (another long story). The third guy is a unquestionably top level Porsche mechanic. He has been testing and replacing everything. I did have brand new injectors in there, but he swapped in others anyway. He also put in a new dizzy, coil and CD unit, to no effect. I wasn't charged for any of them. The list of things tested and replaced is really crazy.

Quite frankly, I'm not so sure it's not that there is simply nothing left. But, I don't know, I didn't ask since he was so distraught over not finding what it is, I didn't want to push it. He did say that if the FD rebuild doesn't fix it, he is paying for it. So, I can't complain about it. I do think I now know who in Alabama rebuilds these, and he sounds like he is simply the best, and is one of the guys Bosch even sends stuff to for rebuilds. So, that works for me!

I know the PMOs are expensive. But, in the end, on the money spent on this issue, I'm not so sure the difference is all that great.

As to my symptoms, the car will not run well or smooth. For example when holding it at mid range rpm, it sort of lightly stumbles "pa - pa ... pa - pa" here and there, it's light, not like the rpm drops noticably, but definitely not 911 correct. Richening the CO mixture helps, but doesn't make it good. At least that was what it was doing which started after the first rebuild, continued after the second, and presumably is still what the symptoms are - again, I didn't ask during our last conversation.

Perhaps I should add what happened during the first rebuild. New P&Cs, Mahles, NOS that had been sitting on someone's shelf, appeared to never have been installed. P&Cs and rods sent to Competition Engineering for honing, balancing, and reboring. Heads rebuilt - which we now know was a very bad job. New clutch - which we now know was bent on that installation, or came bent. Various potential oil leaks addressed, though it wasn't leaking at the time. That's all. It also sat for a long time during this (so bad gas by the time it was running again). The problem did not arise until after this work was done. So, something during this job went wrong. Perhaps related, perhaps coincidence.

It also has since had a new fuel filter, new air box, new Warm Up Regulator, new air valve o-ring, throttle body o-ring, and sensor plate seals, new injectors and injector o-rings, with that special sealing lubricant from NAPA and new intake runner gaskets. Gas return tubes all checked. Probably more things too. I just can't remember right now.

[Gunter]

Glad you have someone now that really wants to find the problem.
A lot of time it's something simple like a bad plug, or ignition wire or many of the other little things.
Hope the rebuild of the FD will do it so you can enjoy your 911.

[Sunroof]

I have a 1973.5T/CIS and plan to replace my FD as well. I have replaced every CIS fuel component from the fuel tank back and I am not pleased with the overall performance right now. A pressure test will isolate the component, or so I am told. In researching FD's I find that very few cores are available for 73.5T's for rebuilding. I was advised NOT TO USE a FD from a newer model, like the 1974, as their are differences! I noticed several catalog competitors have removed the FDs from their inventory probably based on a low core supply. Prices for re-building run anywhere in the low hundreds to over a thousand! Go figure?! I did hear not so good news on the FD rebuilds where you had yours origanally tested, but I have no direct experience with these folks. The rebuilders offered up here on this thread are worth looking at as prices are reasonable and warranties are good. Choices are few, but at least are still out there.

I figure, if I plan on keeping the longhood, it would be a wise idea to replace this old and worn component anyways. Its not going to break the bank and as long as these early cars keep escalating in value and demand, in the long term its well worth it. Besides, a fresh FD should make a very big differene in performance. The FD has been one of those "mysterious" components that never seems to get much attention. The fact is, this is the heart of the fuel system and as old as mine is (original unit) its letting me know its tired.

Good luck

Bob
73.5T Sepia of course

[Jay Laifman]

Originally Posted by Gunter

A lot of time it's something simple like a bad plug, or ignition wire or many of the other little things.

At this point, I don't care what it is, as long as it's found!

FWIW, it has new wires and new plugs. I had Magnecors, which were of course fine, great in fact, but I put in a brand new set of OEM braided wires. They are actually a very nice product should anyone care.

[Fidalgo911S]

Originally Posted by Sunroof

Prices for re-building run anywhere in the low hundreds to over a thousand! Go figure?!

For a FD?! That's stupid money, highway robbery. What's contained in a FD? A plunger and six ports? I took mine off the flow plate to clean the passages and put it back together in under an hour. No issues. Granted I did not seperate the two halves because there was no need. Clean the little filters and the fuel lines and that should be it.

My '74 "CIS issue" was old spark plug wires and one bad injector. I put in a set of Clewetts, rotor & cap, points, condenser, and bought new injectors. The car ran like a top after that.

I agree with the aforementioned post of ignition tune-up. Maybe send your injectors to Witchhunter performance for a check and cleaning too.

[Bobboloo]

Has the fuel been checked for contamination?