1974 Porsche 911 Targa/2.7 Lt. engine

[Ladyheat]

Hello, I'm new to this forum but I certainly need some help and guidance. I have a 1974 Porsche 911 Targa with what I believe is the original 2.7 liter engine. About 18 months ago I had the fuel pump replaced and the car ran fine for about a month and then it started running roughly, had very little power when accelerating and eventually started back firing. I have had it worked on several times but no one seems to be able to figure out what the problem is. For the last 5 months it has been at a shop and the mechanic there believes it needs a new fuel distributor and warm up regulator. The problem is we can't find replacement parts for it. I ran the part number on the fuel distributor that is on the car (0438100077) and it shows to be for a 3.0 liter engine for model years 1979 to 1983. Also the warm up regulator that is on the car has a part number of 0438160001 which I'm told is no longer available and cannot be rebuilt. So my question is what do I replace this fuel distributor and warm up regulator with that will work with this engine and get the car running again. I have been told there is a replacement warm up regulator with the last 3 part numbers of 129 that will work with this engine but no one seems to be able to tell me what fuel distributor should be put back on this engine. I have printed a copy of the workshop manual for Porsche by Robert Bosch and according to it the original fuel distributor for this engine has a part number of 048100017. If I'm able to find the 017 will it work on this engine and if it is no longer available what should I look for to replace it with? Any information and help you can give me will be greatly appreciated. Thanks

[Walter_Middie]

Ladyheat,

There are some CIS experts that can help you here, but this is what I see:

0 428 100 077 is a fuel dist for a 911 SC 1980-1983 (you are correct). This must have been replaced sometime in the past.

0 438 100 004 is the correct fuel dist for a 1974 911

0 438 160 001 is a throttle valve or butterfly valve. On your 1974 this may also have a pressure regulator on it (TCPR). The Warm Up Regulator (WUR) is a different part.
Please help identify this piece

0 438 140 008 is a WUR for your 1974 911

Your last part number must have been written incorrectly. A 0 438 100 017 is a Fuel Distributor for an older 2.4 liter engine, but https://www.deloreanautoparts.com/fuel-distributors.html website shows it for 1973 - 1977 with 2.7 liter engines.

Where are you located?
Is your mechanic familiar with older Porsche 911s? Or is he just a regular car mechanic?

Usually your mechanic will run a fuel pressure test that will tell him what part is not working correctly. It seems unusual that a good running car will suddenly need a fuel distributor and a WUR. Your symptoms may be due to something as simple as vacuum leaks.

There are people on here that rebuild fuel distributors and WURs, if that is what is needed.

[Ladyheat]

I'm located in Oklahoma City, OK. The mechanic owns his own shop and works on all kinds of cars but before he opened his own shop he worked for Oklahoma Foreign which specialized in Porsche so I would think he be familiar with Porsche engines. The car actually hasn't run well ever since the fuel pump went out. That work was done at a Porsche shop but it just never really ran like it should have when I got it back. After about a month I took it back and the fuel pump was replaced again and the mechanic said the first one that had been put on wasn't the correct fuel pump. The car did okay for about a month and then it started acting up again with all the lose of power, missing, back firing ect. If I have the fuel distributor that is currently on the car rebuilt will it work on the car since it's obviously for a different motor or should I try to locate the 004 one for it? On the WUR I actually wrote the number down right from the part myself but my mechanic is the one who told me that part was a WUR rather than a throttle/butterfly valve or a TCPR.
The last part number I got directly from the WorkShop Manual for Porsche K-Jetronic written by Robert Bosch. It shows that part number for a fuel distributor for a 1973 911 T and a 1974 911 or 911 S. I'll see if I can upload the page for you.
If the problem is actually vacuum leaks how is that fixed?
Also on the fuel distributor and the WUR would I be better off just to try and locate the 004 fuel distributor and the 008 WUR rather than having them rebuilt?
Thanks for your help.

[john walker's workshop]

That 80-83 fuel distributor needs to work in conjunction with a frequency valve and computer that allows it to function properly, so that's why it runs poorly, among other things, probably.

[Ladyheat]

The attachment is the information on the fuel distributors taken from the Workshop Manual Porsche K-Jetronic.

[75 911s]

That's not the right mechanic. 5 months? Surely some OK pelicans can direct you to the local CIS mechanic. It requires some finesse. Not saying he's a bad mechanic just not the right one.

[boyt911sc]

Ladyheat,

Buying the CIS components you need to make your '74 to run good again will cost you a lot. And sometimes these expensive components are not even the culprit at all. First, make sure we identify your engine correctly. Post the engine type and serial number.

I could loan you the correct FD and WUR that your mechanic/s could test on your engine. You are not obligated to buy these components. They are loaner. BTW, WUR-008 is not rebuildable.

If I were in your shoes, I would try FD-004 or FD-006 and WUR-009. Or get rid of the TPR (throttle pressure regulator) and use a vacuum assisted WUR. PM me if you are interested.

Tony

[Walter_Middie]

Ladyheat,

You've been given some very good advice from some of our best Pelican members. Let me add to what they have said:

he worked for Oklahoma Foreign which specialized in Porsche

I would tell your mechanic you'd like another opinion. Oklahoma Foreign - Buyer Beware

Several Pelicans have recommended Porsche Repair by Dumont's Porsche Service in Oklahoma City, OK | PCarShops

If I have the fuel distributor that is currently on the car rebuilt will it work on the car since it's obviously for a different motor or should I try to locate the 004 one for it?

John Walker gave some reasons that your Fuel Distributor will not work on your car (assuming your engine is a 2.7 Liter from 1974 - Tony recommended sending the engine number to ensure it's not a 3.0 liter or something else.)

Also on the fuel distributor and the WUR would I be better off just to try and locate the 004 fuel distributor and the 008 WUR rather than having them rebuilt?

I am not afraid of rebuilt items, and Tony made an incredibly generous offer to loan you these components for diagnosis.

If I were you, I'd take the car to someone like Dumont's and have them correctly diagnose the issues. You may have to find the correct Fuel Distributor and go from there. Best of Luck.

[boyt911sc]

Originally Posted by Ladyheat

The attachment is the information on the fuel distributors taken from the Workshop Manual Porsche K-Jetronic.

Difficult to read the headings above the column/s. But some of the numbers are familiar. The 3rd. column is for what?

Model
Year
???
FD
AFM
FI

Thanks, Tony

[Jack Stands]

Have you considered dumping the CIS system and switching over to EFI? The Bitz Racing kit uses the CIS components but then uses modern injectors and electronics. As far as I can tell, the CIS system is similar in operation with other tapered needle carburetors and were a great system back in their day, but we can do much better now.

[Charles Freeborn]

Originally Posted by Jack Stands

Have you considered dumping the CIS system and switching over to EFI? The Bitz Racing kit uses the CIS components but then uses modern injectors and electronics. As far as I can tell, the CIS system is similar in operation with other tapered needle carburetors and were a great system back in their day, but we can do much better now.

Don't do this.

Properly functioning CIS is fine, and your '74 engine (mine too) was designed to run with it. I'll look up my Fuel Distributor and WUR numbers. Tearing into those components is the last resort. Service all the other components first - fuel filter, swirl pot screen, injectors, injector sleeves and all o-rings. Test fuel pressures, flow and pattern at the injectors, proper air flow and plunger operation and first and foremost that there are no vacuum leaks. Also run only clear gas (no ethanol). You can find stations here: http://pure-gas.org

[Targalid]

As Tony said, you need the engine number. We have no idea what engine you actually have. That you have an SC fuel distributor argues that you have an SC engine. Get the number pronto and post it here.

[Charles Freeborn]

My 1974 911S Targa has the following numbers
Engine: 6341146
Fuel Distributor: 0 438 100 004
WUR : 0 438 140 008
All of these components are original to the car.
The engine should look something very similar to this:

I have changed my ignition system to MSD (red box on left side of engine compartment) and the spark plug wires are now red, but the rest of the engine is completely 1974 stock.

[74-911]

Originally Posted by Charles Freeborn

Don't do this.

Properly functioning CIS is fine, and your '74 engine (mine too) was designed to run with it. I'll look up my Fuel Distributor and WUR numbers. Tearing into those components is the last resort. Service all the other components first - fuel filter, swirl pot screen, injectors, injector sleeves and all o-rings. Test fuel pressures, flow and pattern at the injectors, proper air flow and plunger operation and first and foremost that there are no vacuum leaks. Also run only clear gas (no ethanol). You can find stations here: Ethanol-free gas stations in the U.S. and Canada

Agree with Charles, check all the above (although your mechanic should have already done this) and Boyt911sc is an expert on CIS systems, you might take him up on his offer (after you change mechanics). You stated the first fuel pump installed was the wrong one ? '74 fuel pumps are mounted in the rear driver side fender well and are more or less a one-of and are expensive and hard to come by. If your fuel pump is still rear mounted and he installed the "wrong one", he had to really jury rig it to get it to work. This whole fuel pump deal doesn't really add up to me. It doesn't make a lot of sense that it ran OK for a while then started missing/back firing again.
Has your mechanic checked the points/coil,CD box. etc. to be sure it is not an electrical problem?.

[Ladyheat]

The engine number is 6143499. This is the number that runs horizontal and I understand there is another number below this one that runs vertical however it isn't visible because of some type of metal plating over it. There is also a gold colored metal plate on top of the fan housing that states the engine is a 2.7 liter and the engine looks pretty much identical to the 1974 911 picture shown.

The fuel distributor that is currently on the car has a part number of 0438100077 and the part number on what my mechanic said was the warm up regulator is 0438160001. I also understand that the 2.7 liter engine has points and the 3.0 doesn't so I verified that my engine has points and it does. The third column on the page taken from the shop manual is for fuel distributors and the number in the box is 0438100.

Dumont's is actually the shop that replaced the fuel pump on the car and then had to replace it a month later because they said it was the wrong one. At this point I'm going to have the car towed back to Dumont's and see what they have to say about it. I will definitely take the offer of a loaner on these parts to see if they will work if Dumont's believes that is what is causing the problem. At least that way we'll know for sure and if I need to have the parts re-built if that's a possibility I'll definitely take that offer as well. As soon as I can get over and take a picture of the engine, fuel distributor and warm up regulator I will post those as well. The current mechanic told me he believes that I got some really bad gas even though I don't run ethanol in the car and the injectors are going to have to be cleaned and the gas tank replaced. He doesn't believe the gas tank can be cleaned rather than replaced because the gas in it is such a bad color.

Thanks for all the input. I'll be posting again soon when I have information from Dumont's. L

[Walter_Middie]

Ladyheat,

Your engine number appears correct for a 1974 911.
614 3499
6 = 6 cylinder
1 = 911 type 911/41
4 = 1974
3499 = sequential serial number usually starting from 0001

Seeing that is has points is another good clue that this is 2.7L.

As mentioned before, the fuel pump is located in the left rear wheel well. They don't sell these anymore, and the replacements are usually mounted up front with some modifications. It could be that Dumont's tried to use a fuel pump that was not stock, as they could not get a stock one.

[Charles Freeborn]

Correct. The original fuel pump is nla. The replacement is the Pierberg sold here. It does require some modifications to get it to install correctly.
Pierberg Pump Install
If you choose to change the fuel pump ( or already have) to a front mounted one (up near the gas tank) you ABSOLUTELY MUST change the fuel line running through the tunnel of the car. The original fuel line is vinyl and should be replaced anyway, but ESSENTIAL is that it is not meant for the high pressure that the pump puts out. You risk a high pressure fuel leak, and if it happens back where the original fuel pump is located it will spray fuel on your exhaust system.
If the pump has not been switched with one that puts out the proper pressure your CIS will not work correctly no matter which FD or WUR you've got.
A great source for CIS parts and repair is CIS Flowtech - Rebuilding Bosch Fuel Distributors & Warm-Up Regulators
The electric WUR on '74 cars is not rebuildable.

[pmax]

Originally Posted by Ladyheat

He doesn't believe the gas tank can be cleaned rather than replaced because the gas in it is such a bad color.

If the gas is bad, all bets are off.

I would fix this first and foremost before racking up hourly charges with the mechanic swapping CIS components for you.

[juanbenae]

Originally Posted by pmax

If the gas is bad, all bets are off.

I would fix this first and foremost before racking up hourly charges with the mechanic swapping CIS components for you.

I agree with pmax. but the color of bad fuel is subjective, it's the smell you will notice. it will quit smelling like gas and smell like varnish. there have been some great suggestions above, but if I were looking to make this right prudently id consider the fuel system. it's hard to say what's up with a tank from afar, but have it pulled & take it to an independent place to be evaluated & cleaned. if it can be flushed out and returned to service you could save a ton money over new. if they say it's junk it's already out & buying a new one is an easier decision.

if the intent is to get the car running as economically as possible the relocating of the fuel pump is a great idea in the long term, it will however be costly to go that route now. I have just done this for a project car and would be happy to send you a working fuel pump from my 75 I will not longer be using. not worth selling in the classifieds as I can only state "it was working when removed". if yir in a pinch this might save you a few hundred bucks. the draining of the tank for evaluation might be a pain as shops hate to do this. they'd rather sell you a new one. buyer beware.

really, until you can be sure the system is getting good, fresh fuel from the pump & filter system all bets are off. if the tank is junk there are particles making their way to new fuel filters and pumps ruining them you are spending fools money.


lastly, if the car has been anywhere for five months it's time to consider a new shop. if the long duration suited your budget better, well then proceed. however if a shop holds a car that long with no clear analysis of the issue then they likey don't know. buyer beware.

t

[boyt911sc]

Originally Posted by Ladyheat

The engine number is 6143499. This is the number that runs horizontal and I understand there is another number below this one that runs vertical however it isn't visible because of some type of metal plating over it. There is also a gold colored metal plate on top of the fan housing that states the engine is a 2.7 liter and the engine looks pretty much identical to the 1974 911 picture shown.

The fuel distributor that is currently on the car has a part number of 0438100077 and the part number on what my mechanic said was the warm up regulator is 0438160001. I also understand that the 2.7 liter engine has points and the 3.0 doesn't so I verified that my engine has points and it does. The third column on the page taken from the shop manual is for fuel distributors and the number in the box is 0438100.

Dumont's is actually the shop that replaced the fuel pump on the car and then had to replace it a month later because they said it was the wrong one. At this point I'm going to have the car towed back to Dumont's and see what they have to say about it. I will definitely take the offer of a loaner on these parts to see if they will work if Dumont's believes that is what is causing the problem. At least that way we'll know for sure and if I need to have the parts re-built if that's a possibility I'll definitely take that offer as well. As soon as I can get over and take a picture of the engine, fuel distributor and warm up regulator I will post those as well. The current mechanic told me he believes that I got some really bad gas even though I don't run ethanol in the car and the injectors are going to have to be cleaned and the gas tank replaced. He doesn't believe the gas tank can be cleaned rather than replaced because the gas in it is such a bad color.

Thanks for all the input. I'll be posting again soon when I have information from Dumont's. L

Ladyheat,

Not all good mechanics are well familiar with CIS. And vise versa. I say this because your mechanic mistakenly identified your TPR (0-438-160-001) as your WUR (0-438-140-008). They don't even look similar and located far away from each other on the engine. I would not even consider this blunder a typo.

Think hard and make your decision. The shop maybe reputable but the mechanic working on your car is questionable. They installed a new FP and was later determined to be the wrong type. Now, they don't even know what and where the WUR?

Is this there any shop/s in your area that has a mechanic very familiar with CIS-Ketronic? I know a guy who owns a '78 SC and works as a Service Manager for a well established Audi and Porsche cars dealership. He has 25 well trained mechanics under him and none of these young mechanics know about CIS troubleshooting. As a matter of fact, I lend my pressure gauge kit for them to check the fuel pressures. And their hourly rate was more $100.

Tony