Pelicans, I need your help.

[Starless]

OK, I will try to make this as short as possible. The company I worked for for 27 years filed for bankruptcy protection 3 years ago and let go all senior employees to save money. I worked as a film camera repair tech. I am now self employed but the amount of cameras coming in is as you can imagine getting pretty scarce. The one saving grace is that the large camera repair company that was my only real competition downsized and moved most of it's employees down south. They also stopped repairing film cameras. My wife has a decent job so we're not looking at loosing our home or going hungry. But............and here is where the Porsche comes in, I feel that it's only fair that if we're going to keep the 911 I am going to do as much repair as possible myself. I have always done what I could, oil changes, brakes, tune ups, etc. Simple stuff. I suck at diagnosing problems.
So here is my problem, and believe me have been searching for a couple of weeks on this site to try and figure it out on my own. When i start the car cold, it starts and dies. As I try again to start it, it will backfire through the pop off valve, i can hear it slam open and close. After a few tries it will stay running, poorly. If I give it gas it will backfire. After a couple of minutes I will be able to drive it out of the garage but as I give it gas it backfires and has no power. So being stubborn I drive it around the block and it barely makes it up a very small hill. After about 10-15 minutes, as it warms up, it starts to run better, no back fires. When it's all warmed up it runs pretty good but it's still not the way it should be. When I stomp on the gas in 3rd it doesn't take off like it used to. It was running fine when I last drove it, but it did sit for about 3 weeks prior to this. I have replaced the dist. cap and rotor and put some techron in it as I had them new in the garage and felt it couldn't hurt. Sorry for making this so long. So, any ideas of where i should start?
Oh, it's a stock 1980 SC.
A pic for the hell of it. Thanks for listening.

[emac]

Sounds like your popoff valve is not seating. Also after the first start do not pump it. Would go on but I suck texting in a phone
Ernie 81 SC

[Jbp]

Runing to lean.
Fuelfilter?
Fuelpump?


Jocke.

[Starless]

Ernie, Jocke, thanks for your ideas, but why would it run so much better after it warms up if it was the popoff valve, filter, pump or running lean? Just asking.

[Flat6pac]

Without a pressure test on the fuel its guessing but it sounds like the warm up regulator is on the fritz. Pressures need to change over the warm up. Also, being an 80 SC with lambda, the relay under the passangers seat, when it goes bad it act like a defective WUR, and its inexpensive available at local auto stores.
Bruce

[kodioneill]

Originally Posted by Flat6pac

Without a pressure test on the fuel its guessing but it sounds like the warm up regulator is on the fritz. Pressures need to change over the warm up. Also, being an 80 SC with lambda, the relay under the passangers seat, when it goes bad it act like a defective WUR, and its inexpensive available at local auto stores.
Bruce

I agree with Bruce.

[tirwin]

Starless,

I am NOT a CIS expert (hopefully some of the guys will chime in soon), but I think we can help you. Have patience. Take a deep breath.

I have learned a good bit since I bought my '83. If I can do it, you can do it.

First thing, let's address some basics. There are several common causes. Vacuum leak. Poor spark. Fuel pressure. Too rich, too lean. You could have a combination.

The good news is that a lot of troubleshooting this is not about parts swapping. The first thing you will need is a set of CIS fuel pressure gauges. I bought a set on Amazon for about $100. You might be able to borrow a set. I'm reading this on my phone so I can't tell if you have your location in your profile. If not, put it in and someone might be kind enough to come over and help. A cold beer is cheap.

Your car has a WUR - warm-up regulator - aka, the control pressure regulator. Part of the WUR's job is to adjust the mixture at cold start. If you drive the car and let it get warm and turn it off and then start it again, does it exhibit the same symptoms?

There are several things to check. Do you have the Bentley manual?

Some recommended reading is to search the forum for the keywords "CIS" and " cold start". You should find plenty to read. There is a good website for CIS troubleshooting. I will post a link later tonight.

Have patience and you'll get this sorted out.

Good luck!

[gtc]

I ran into a similar problem on a friend's SC, and it turned out to be the O2 sensor relay (under the passenger seat). I replaced the ancient relay and cleaned up the socket, and the problem went away. It is also driven off the dome light fuse, so check that while you're at it.
If you do a search for "oxygen sensor relay" here in the tech forum, there are a number of people who think their WURs are going bad, but then find that it's only a bad relay.
And many thanks to John Walker for one of his posts on the subject. It brought several hours of frustration to an end for me.

Edit: Looks like this is what Bruce was talking about in post #5 above.

[everforward]

I recently had this problem and I suspect it was bad gas from Shell or some how some moisture worked its was in there. It ran fine after I filled up, but after I parked it for about a week and a half I had the same exact problems as you did. I was very frustrated and gave up for a day or two. I did some research on Pelican and I heard about the Techron tune up. Well low and behold after 2 more days of doing nothing the car started fine. I had already sourced a bottle of Chevron Techron and I immediately drove my car to the nearest Chevron station added the bottle of Techron and topped off the gas tank with supreme. I then took it for an Italian tune up, 3 runs at 100mph for about 1/2 mile each. I have not had a problem since. I hope your issue is as simple as mine was. Good luck.

[Targalid]

My thoughts are similar to Everforward's. You have water in your fuel tank. With 10% ethanol in the fuel, the condensation from moist air can quickly saturate the ethanol and cause it to separate as a watery mixture in the bottom of the tank. This less than combustible mixture then is preferentially pumped into the fuel system. My guess is that you had the car parked for most of the winter and are just now getting it running again. Try running a series of fuel conditioners through the tank. Check the internet for a fuel station near you that provides ethanol free gasoline. I don't discount the information about the oxygen sensor relay under the passenger seat. Check that too but my bet is on water in the fuel. Best of luck. My wife just had her computer programming job outsourced to India.

[porwolf]

I seem to remember some time ago it was not uncommon that gas stations or delivery trucks were exposed with water in their tanks. So, the water could come right with the gas you are pumping.

[Jdub]

You mention you just replaced the distributor cap and rotor. I would focus on ensuring the parts are correct, then confirm that the wires are all connected to the correct distributor towers. Check those grounds. Then, be sure your battery is 100% charged so you are not leaning on the diodes in your alt. etc. - give your car every benefit.

Did you turn the distributor? Is it loose in the engine case? Check your timing if possible.

May seem elementary but you have to ID either something you did to the car or what can happen when it sits (bad gas; condensation; drained battery; etc.).

[Starless]

Thanks everyone. I did check continuity across the 2 terminals on the WUR. There was continuity but my multimeter is of the old dial type, so not very accurate. I'll get my neighbor the retired electrician over and get a reading. The lambda relay, I did a search in the Pelican parts catalog, can't find the part for the lambda relay. Dome light works, but I assume that just mean the fuse is ok not necessarily the relay itself. Is there a way to test relays? Wait, after re-reading the posts above, I'm guessing the lambda relay is the oxygen sensor relay, correct? You see, I do need help, but I want to do everything i can to get this done myself. With your help of course. The dist. cap and rotor are new, just got them from Pelican a couple of weeks ago. And no my dist. is not loose, it will not turn. The battery is only a couple of years old and I disconnect the neg. cable when I know the car will sit for more than a couple of days.
OK so this is what I plan to do for now. The easy stuff first. I'll replace the relay, and run some dry gas and see what happens.
The only books I have are 101 projects and the Haynes manual. I will have to look into finding a copy of the Bentley. But, just for future knowledge, is there a way to test relays?

[tirwin]

Here is the link to the CIS info I promised:

CIS Primer for the Porsche 911

[Starless]

To answer tirwins question, once the car is warm, if I shut it down it starts right up fine as long as it doesn't get the chance to cool down too much, but it still a bit sluggish. It just ain't got that zip it had. If it sits overnight, I'm right back to the original problem.

[Starless]

Thanks tirwin, I have that saved on my desktop. I just don't know where many parts are located on the engine, or what they even look like or how they are supposed to work. I can fix a Pentax K1000, but when it comes to cars.......

[tirwin]

Here is a link to the Porsche PET catalog:

Porsche Original Parts Catalogue - Parts and Diagnostic Information - Porsche Service - Dr. Ing. h.c. F. Porsche AG

I have the PDF version saved for handy reference.

The other link I sent has part numbers for some components. You can cross reference it to the PET and it will show you where it is in the car. (Adobe Reader will let you search the PDF.)

If you go to the troubleshooting link on the CIS Primer site, look at the possible causes that are in common to the symptoms you have.

Bad gas is relatively easy to rule out so do that first. If the problem persists you want to first make sure your fuel control pressures are in spec. The Bentley manual has the procedure in section 240.

If you search for "CIS troubleshooting" (or it might be "troubleshooting CIS") you will find my thread where I started from square one. I replaced rotor, cap, plugs, wires and did a valve adjustment and it made a huge difference.

I am not a CIS expert by any stretch -- there are plenty of people on here that understand it much better than I do, but given what you've done for a living you are accustomed to troubleshooting so you can do it. Focus on understanding the principles of operation first and it will start to come together. You just have to take what you already know and apply it to this.

[flatsicks]

Don't know if a 32 year old 911 is the right car to own when on a very tight budget but that is another story. Parts/ repair cost get costly very quickly, it is a P car after all.

I'd look into the WUR as well - sounds too familiar.

[Starless]

Flatsicks, we're not really on a very tight budget, no kids. Just feel that whatever I can do to save some money is worth it. Plus I really want to learn, as I'm now semi-retired it's now my hobby. Beats hanging out at the bar. Also when we bought the car over 10 years ago we were in a different situation. Plus it's been a very reliable car, it's paid for, and we have 2 other cars, so it's not like I depend on it to get around. I've been thinking WUR also after all the reading i did. I just added some fuel conditioner in case there is some water in the fuel. My local auto parts store has a ox sensor relay in stock, I'll try that too. Then on to maybe the WUR and fuel pressure. One step at a time. I'll let all of you know what happens as it happens.
Again, thanks all.

[boyt911sc]

Juan,

The way you described your car's running problem/s, I would say it is minor and would not worry too much about it. So, if I were in your shoes, I would check the following:
1). Fuel pressures (control and system).
2). Unmetered air going into the system.
3). Relay for the FV (frequency valve).
4). A dwell meter would tell a lot about the OXS/ECU. (Optional).

Investing on a fuel pressure gauge is the best $$$$ you'll spend on your car and reference books/manuals about fuel injection systems. Until you know the fuel pressures and integrity of your vacuum/air system, you'll be doing a lot of guess work. Not only it would be time consuming, you might be replacing components unnecessarily. Keep us posted.

Tony