HELP! 2.7L runs only when gas poured in.
 

Novice here.

I have a 1974 911 that has been sitting for a number of years. Cleaned fuel tank and lines but it will only run when I pour some gas in the Throttle Body and stop after several seconds when the gas runs out. Let me say I know nothing about these systems.

It is getting gas to the Fuel Distributer and gas is going to the part in the picture below. Im guessing that is the Cold Start Valve? (I have a service manual but the picture is different) The line going into it is from the center of the Fuel Distributer and gas comes out of that. The arrow in the photo points to a line that looks like it is going back to the Throttle Body. When I pull that line it is dry. Any help is greatly appreciated!
http://forums.pelicanparts.com/uploa...1601232388.jpg

Mark,

The part you are looking at is called the Warm Up Regulator (WUR). This in not a good name, as this device regulates fuel pressure at all times (not just during warm up). There are threads on how to take apart and even to modify it so that you can adjust the pressure yourself. These are pretty easy to remove from the car and take apart - not much to them.

http://forums.pelicanparts.com/porsche-911-technical-forum/272502-modified-my-wur.html

So you think that’s the problem since the line I’m pointing to is dry?

WOW, a guy that admits he knows nothing questions a guy who knows a lot!

I wasn't suggesting that you need to modify your WUR - I was just pointing to a good thread with pictures - such as this one:

http://forums.pelicanparts.com/uploa...1208278116.jpg

If you're getting fuel into the WUR and not out, there must be something hanging up in there - or you're not developing enough fuel pressure to operate the WUR. You may need to get some pressure testing tools - I'd still pull the WUR and see if it looks OK inside it.

Ok, it’s my WUR in the picture but I asked if the one line that is dry is an indication of it being at fault for not drawing fuel. His link is to modify a WUR. Can it be rebuilt? How do I know if it is at fault? Do I test the connection? I need more info if possible. I just want to get the car running and not start modifying things.

Thanks. I guess I’ll look for something. I’m an old school V8 guy. Porsche stuff new to me. No Holley there.

Patience. Take the time to get it right, and it will run great for years.

Mark, good job on getting a 74. I have one also that was only a little better running than yours 2years ago. I just got back from a 100 mile loop. You can get it to run properly with patience and reading; starting with the "CIS for dummies" thread. CIS is basically a system of parts that have
to work together to perform well. The 74 is the most "basic" fuel injection system with the least amount of components. Start by identifying all the components and their function. CIS sitting is the worst thing. some thing is most likely gummed up. Lots of good info on this forum to help you.
I too am a carb guy, surprised you got the car to do anything dumping fuel in throttle body.

Everything looks ok inside. Is there a test for the wiring?

http://forums.pelicanparts.com/uploa...1601240961.jpg

18 to 22 ohms resistance between the contacts. Also, make sure there is 12 volts all the time to the WUR.

Getting 36 ohms between contacts in WUR.

If the WUR looks OK, and you don't have a fuel pressure tester, I'd also check the fuel pump delivery. It should be at least 850 cc in 30 seconds. This can be tested from the output of the fuel pump, output of the fuel filter, and the return line to the tank.

You may be able to borrow a fuel pressure tester from a local auto parts store.

Mine was as high as 30 ohms - yours may be tired, but it was not an open contact. It should still work.

Ok I’ll need to check fuel pressure. Might take a few days.

Wur
 

I'm not a CIS expert, but I believe that the hose you have the yellow arrow pointing to is the vacuum hose and should be dry. The fuel lines are the other two in the pic.

http://forums.pelicanparts.com/uploa...1601242390.jpg

https://jimsbasementworkshop.com/CIS/CIShome.html

regards,
al

Can you blow compressed air through the WUR ports.

The line you point to had fuel in it. The small one with the hose clamp appears to go to the return fuel line. The one with the yellow arrow could be a vacuum line since there was no clamp on it.
I could be attacking this all wrong.

I'll confirm that - Line with yellow arrow is vacuum and should be dry.

Here's a link to help with CIS troubleshooting:

https://jimsbasementworkshop.com/CIS/

Al is correct:

http://forums.pelicanparts.com/uploa...1601246251.jpg
http://forums.pelicanparts.com/uploa...1601246251.jpg

With the key in the run position, your fuel pump should be running. If you lift up on the air flow plate (under the air filter), do you hear your injectors running? Air in the lines may keep the fuel from getting to the injectors. Be careful not to flood the engine with this test.

May I suggest before you do anything follow the link Al gave to familiarize yourself to the cis. Learn some basics and also get a proper cis pressure gauge test set. Also check out the cis for dummies thread on here.

Thanks, I’ll do some more studying up.

Yes I hear a slight squeal.

Disconnect all 6 vacuum lines from the injectors, put them in a jar, lift the sensor plate and see if fuel comes out. The reason for disconnecting the fuel lines is, lifting the sensor plate shoots fuel to all 6 injectors at the same time and will flood the engine if you over do it.

You have ignition - as it rums with fuel added to the throttle body. You have fuel to the injectors as you hear squealing. These cars are very hard to start without the cold start injector working, but adding fuel to the throttle body should compensate for that. Seems like this car should start.

Anybody else have a suggestion?

Pull all your injectors out and put each one in a plastic bottle. Lift up on the air flow plate and see if each one is spraying. The spray should be in a perfect cone atomizing as much as possible.

Report back and we can go from there.

Rahl

All injectors squirting equally and good pattern.

OK - Couple of quick things to check:

- Verify no holes in the rubber boot between the throttle body and the air flow sensor.

- Verify no open ports to the air box.

- Verify that the hand throttle (black-knob next to the parking brake) opens the throttle plate when you pull it up.

Rough starting sequence:

- Hand throttle all the way down.

- Turn key to run position, let fuel pump run ~15 seconds

- Pull hand throttle up ~1 inch

- Crank the starter

- Adjust idle speed with the hand throttle if it catches/runs

It should still start (might be tough) if the cold start valve isn't working.

Will check in the morning.

Warm-up Regulator identification......
 

Mark,

It would be much easier to help you if you understand the basic CIS fuel flow schematic. You said you have a ‘74 CIS, and that’s a good start. Since you know now the difference between a CSV (cold start valve) and a WUR (warm-up regulator), start reading or learning the different common acronyms people used in this forum.

The first thing I would ask you is what is the ID number of your WUR? If your are not familiar with Bosch WUR identification number (0-438-140-xyz), the last 3 digits identify a particular Bosch WUR. It is located on top near the post where the rubber hose is connected. I could see the numbers from your picture.

Depending on the last 3 digits (xyz), you could identify a particular WUR whether it vacuum assisted or not. Except for a rare or hard to find WUR. Second, the rubber hose with yellow arrow could be vacuum or vent line depending where it is connected at the throttle body. Before we get into further discussion, you need to identify this particular WUR. Thanks.

Tony

Be very careful not to over fuel the airbox, otherwise you will be in danger of an airbox backfire, it will ruin your day.

If all injectors are working well and understanding it runs when fuel is applied directly e.g. a spark is present, it should at least fire if not run. Unless maybe the air flap is closed/blocked in normal operation.

It will run when gas is put in directly. Just won't keep running. Has good spark. Compression and leak down numbers were good (checked by Vision Motorsports in Laguna Hills). Car has security systems that I disconnected but wonder if they are still somehow effecting it. Could be bad CSV? It's going to be 80 degrees today. Will try what Fanaudical suggested.

WUR is 0-438-140-009

Not sure how you are getting fuel into the TB but if the rubber bellows "popes hat' is not secure and air tight the car won't run.

Ok didn’t realize pope needed his hat. Buttoned everything up and let fuel pump run for 15 secs. And used hand throttle.

CAR RUNS!!!!!

Thanks to all!!!!

Let the fun begin.

Yes, the air boot between the throttle body and the air flow sensor must be installed and sealed well (or else the air flow sensor won't lift and injectors won't get fuel).

FWIW - The "run the fuel pump for 15 seconds before cranking" is either total hogwash or standard operating procedure, depending on who you ask. I find my '75 starts very quickly if I let the fuel pump run/prime things for a few seconds.