73.5 cis help

[gibran911]

Hello. I am rescuing a 1973.5 Porsche 911T Targa from the Arizona desert. It has sat for about 16 years, only started occasionally and driven around the neighborhood by the previous owner.
I started out draining the tank of old fuel, about 1 gallon, through the drain plug at the bottom of the tank (screen was clean) and replaced all six injectors as well as the fuel filter.
The car starts right up and runs and drives, well sort of... here's the situation.

#1 injector flows as soon as the key is turned on and the fuel pump engages. none of the other jets do this. If the key is left in the on position, the#1 cylinder fills with fuel and the car wont start - Hydro lock>until I turn the motor by hand and relieve the fuel from the cylinder. Once the car is started the excess fuel comes out the exhaust.

Q) Is this problem related to the fuel distributer or perhaps another component of the CIS?

Any Idea's or experience with this? I know that I will probably be doing a complete shake down of the system, from tank to the injectors and all points in between.

[boyt911sc]

Originally Posted by gibran911

Hello. I am rescuing a 1973.5 Porsche 911T Targa from the Arizona desert. It has sat for about 16 years, only started occasionally and driven around the neighborhood by the previous owner.
I started out draining the tank of old fuel, about 1 gallon, through the drain plug at the bottom of the tank (screen was clean) and replaced all six injectors as well as the fuel filter.
The car starts right up and runs and drives, well sort of... here's the situation.

#1 injector flows as soon as the key is turned on and the fuel pump engages. none of the other jets do this. If the key is left in the on position, the#1 cylinder fills with fuel and the car wont start - Hydro lock>until I turn the motor by hand and relieve the fuel from the cylinder. Once the car is started the excess fuel comes out the exhaust.

Q) Is this problem related to the fuel distributer or perhaps another component of the CIS?

Any Idea's or experience with this? I know that I will probably be doing a complete shake down of the system, from tank to the injectors and all points in between.

Gibran,

I just posted a similar picture earlier to assist another member with his problem. The way you described it, it looks like one injector is stucked open and spraying fuel prematurely. To determine whether this is true or not, fabricate something similar to this set-up. Then turn the ignition to switch @ RUN/ON and the FP will start to run as per '73.5 CIS model'.

There should be no fuel coming out from any of the injectors. No mist or drip at all!!!! If you find any injector/s delivering any amount of fuel at this early stage, either the injector/s is bad (dripping) or the air-mixture screw is set too rich. Do not touch or alter the air-mixture screw!!!! I would bet the injector is bad.

Your goal is to have the FP running with zero drip (fuel). Sometimes the fuel injector could be refurbished and cleaned by pressure cleaning. Install the defective fuel injector in another line and test. Start from this and keep us posted.

Tony

[Gogar]

1. I don't know if it's even possible, but make sure the line to your Warm Up Regulator (which comes from the center of the Fuel Distributor) didn't somehow get switched with the line for #1 (which can come from your choice of the other 6 on the top of the Fuel Distributor.) That would cause fuel to get to the #1 injector all the time regardless of sensor plate position, and an improper amount of fuel everywhere else.


It's also possible the Fuel Distributor is dirty, especially after sitting so long.

If you do remove the FD for cleaning, make sure that you DO NOT take it apart, and

Make sure when you remove it from the airbox that the center pin does not fall out. It's delicate and any nicks or burrs on it at all will make it useless. You can remove it and carefully clean it, just don't drop it or scuff it up.

Tony's suggestion is also a cool thing to do. You can also perform the test with just the fuel lines only, no injectors, if you like.

[moneymanager]

Gogar, it is possible. I did it several years ago. Car didn't work well at all. If everything has come apart, this is something I'd check before doing anything else.

[bfunke]

There are some interesting and informative posts past few days on refurbishing the fuel distributor. May want to search for them. Seems they can be rebuilt successfully.

[gibran911]

Ok - so far only #1 fuel injector sprays fuel with the key in the on position and that is with a new injector. I did the six injectors into six cups initially to determine if they needed to be replaced and found them to be all over the map, so I replaced them all. #1 still sprays when key is in the on position.

Im pretty sure that all the fuel line are in the correct position, but I will re-confirm that later today.

Is it possible to clean the fuel distributor without opening it up? from what I have read, there are only 3 guys people recommend to have rebuild one. Or you buy a kit and cross your fingers as new or rebuilt ones are either NLA or Big$.

Any other ideas?

Thanks again to all who replied,
Gibran

[Walter_Middie]

If it were mine, I'd swap #1 injector and another - if your leaking injector moves to the new spot, then the new injector is bad. If that doesn't work - I'd follow Gogar's advice and remove the FD and make sure the plunger is free to move and not stuck. Then I'd check to make sure the air flow plate is adjusted correctly, and at rest, it is not hung up.

If none of that works, then you might be looking at options for a rebuilt FD.

[Gogar]

I'm still wondering if someone swapped the middle fitting on the FD for #1, and the gas that should usually be going to the WUR is just getting sent to #1.


Pull the gas line that is going to the Warm Up Relay (which is bolted to the #2 intake runner) and stick it in a bottle or something that will catch gas. Turn on the key and see if gas comes out of that line!

[gibran911]

Sorry for the delay. work and the weather are keeping me from doing any further investigating at this time, but as soon as I can I will update.

Thanks again.

[boyt911sc]

Originally Posted by Gogar

I'm still wondering if someone swapped the middle fitting on the FD for #1, and the gas that should usually be going to the WUR is just getting sent to #1.


Pull the gas line that is going to the Warm Up Relay (which is bolted to the #2 intake runner) and stick it in a bottle or something that will catch gas. Turn on the key and see if gas comes out of that line!

gibran,

Could you post a couple of pictures of the FD and line to the WUR? This will answer some nagging question about your set-up. Switching the #1 injector to another line is a good test to determine if #1 injector is the culprit or something else. I doubt it is the plunger!!! Otherwise there will be more than one injectors spraying fuel if the plunger was stuck on at upper position. Just a thought.

Tony

[gibran911]

OK - I have confirmed that all the lines are hooked up correctly and have photo's. still not understanding why #1 is getting fuel when key is in on position while all the others are idle.

Have not had the time to dig deeper, but will continue this week. I'll keep you updated.

hanks again and Happy New Year.

[gibran911]

Hello. Today, with the help of two good friends, pulled out the motor of my 1973.5 porsche 911T Targa. The initial question I had concerning the fuel distributer is answered - Rebuild it! After seeing a thread on it, we have decided we can do it.
Additionally, after seeing a thread concerning hydro lock, decided to check into the motor further - top end and bottom if needed. This will be a lengthy endeavor, but one that will be well worth the time and effort. Oh, and MONEY. As I stated in my first line, I found this car locally (I live in Tucson, Arizona) and knew it had been sitting for the better part of 16 years and only driven occasionally around the neighborhood by the owners kids. Not doing a complete restoration, rather a mechanical overhaul on the car to make it a solid daily driver in as much of "original" condition as possible.

More to come.........
Thanks again, Gibran

[HarryD]

Giban:

You are driving what I consider the best early 911 for street use. Of course I am biased...

Looks great and you will have a ton of fun.

[Walt Fricke]

Gil

Did you swap the #1 injector for the #2 and vice versa? And did you find that it was still the #1 fuel line (now with the #2 injector on it) which was a problem? Thus confirming that all of your new injectors worked properly?

Because it is possible for a new injector to be bad. Not common, but possible. I suppose you know that the injectors have a "cracking" pressure: they stay closed until the fuel pressure rises to a certain point. Only then do they spray anything. So many (like Tony) who responded thought that a bad injector could do just what you have found.

If you haven't done this, you really need to before you go messing around with "rebuilding" your fuel distributor. Given the limited amount of what can be "rebuilt" as opposed to just cleaned, you need to be realistic here. If it is one bad new injector the fix is very simple.

It is a bit hard to know what in the fuel distributor could cause this, and at the same time be something you (or perhaps anyone) could fix.

Each fuel distribution line gets its fuel through its own differential pressure chamber. A diaphragm separates the fuel in the upper (fuel line) part of this chamber from the fuel in the chamber under it. That lower fuel is at "system" pressure, so if it can bypass (through a torn or otherwise incompetent diaphragm) the fuel control plunger and the related metering slits, it will have plenty of fuel pressure (with the fuel pump running) to push a veritable gusher of fuel out of its injector.

I don't think you can get replacement diaphragms. If this is the cause of the problem, cleaning won't help. I've only had a fuel distributor apart once, and that was just to clean it and get the plunger to stop sticking. I noted the diaphragms and moved on. If it can be removed, I suppose you could scavange one from a junk fuel distributor.

Another possibility (pure guesswork based on how the distributor works) is wear on the slit for this fuel line. If the slit wore so it extends lower than the other slits, possibly even a closed plunger might still leave the bottom of the slit exposed and thus provide a path. If this is so the unit is junk, as there would be no practical way to repair this. While abrasive wear seems unlikely in an engine which mostly sat for 16 years, who knows. Rust doing the same thing?

[gibran911]

Hello,
Hi Walt,
Yes, I did rotate a couple of injectors onto the #1 line and found all to squirt fuel (only when attached to #1 line - not on any others) so, unfortunatly it is not simply a bad injector.
I wish there was an easier way to fix the problem, but right now the plan is to open the fuel distributor and see what could be causing this. Rust, bad o-ring, or torn diaphram? From what I have read, it should be possible to do this.
My hope is that it is either rust, or an o-ring or some other debris holding the port open and allowing fuel to pass at the incorrect time. Any Idea's?
Gotta run, thanks again.

[kodioneill]

Bad fuel distributor. Dirty fuel distributor.

[gibran911]

Started engine tear down and will start the process of opening and inspecting the fuel distributor today or tomorrow

[gibran911]

Ok, so We did it and it was not that hard. Here are the photo's of the fuel distributor opened up and the reason why #1 was getting fuel. The O-ring was not seated properly. The O-ring must have slipped during previous rebuild (Wow) and did not seal correctly, allowing fuel to flow through the circute and into #1 injector The previous owner stated that it had been rebuilt and it was obvious that it had. Probably why it sat so long and he finaly sold it to me (Luck?).With the help of my good friend Chris Janson, who is The Volkstop ( VW repair and restoration and now Porsche - He owns two, A 71 and 74) here in Tucson, we were able to clean it and put it back together with new O-rings. It will be a while before we can run it as the motor is out of the car for a once over.




Stay tuned for more Porsche Excellence,
Gibran

[KNS]

Let us know how it turns out...

[kodioneill]

Way to go guys. Well done. It's nice to see someone listen, take action, and solve a problem.
GOOD LUCK!