Desperate in SE Michigan

[azasadny]

Folks,

I've read in a few posts that there are kind souls who will assist in troubleshooting for beer/food, etc... I'm having a cold start problem on my 1974 911 (2.7 with CIS) and I would gladly provide food (brats, tacos, steak, sushi, whatever) and whatever beverage you would like (German or Belgian ale, whiskey, tequila, etc...) if someone could help me out.

I think the problem is either electrical or (more likely) fuel pressure related and I don't have the tools (Bosch fuel pressure gauges) to troubleshoot very effectively. The car ran great last Sunday and it starts when warm, but not cold.

I have replaced the CD unit, plugs, points, rotor, dist cap, cold start valve, thermotime switch, battery, fuel accumulator, fuel filter, etc... and no improvement.

There is a shop near me but not being able to start the car is a problem. If I can't figure this out by Monday (5/12), I'll have to take it to the shop and I REALLY don't want to do that. I've checked everything I can think of and nothing has helped.

Any takers??? When the car finally starts, it runs great, I'm frustrated beyond description...

[silverc4s]

I wish I could help. Sadly, the one system that I have zero experience with is CIS, so I am not your guy.. Way too far away as well. Have faith, I'm sure that help is here, just about to show itself..;-)

[Tim Walsh]

do you get spark and fuel while cold?

[Volkovich]

I had a cold start problem on my 1979 and the Bosche fuel gauge and my Bentley manual helped me zero in on the problem really fast.

When you say it doesn't start, is it starting really, really hard or not at all? Mine would start, stall. Start, over-rev, stall and finally after a lengthy warm up I could give it gas and it would run.

My problem ended up being the warm-up regulator (mine was plugged shut and had a bad heating element). The problem was my car was ALWAYS getting full system pressure (5bar) when it should have been getting 1.5-2.0bar at start-up and then 3.6bar when hot.

Might want to try cleaning the little screen in the fuel inlet side of the regulator. Wouldn't hurt...

[azasadny]

Guys,

Thanks for the advice. I'll recheck everything this weekend, but I don't have a pressure tester. I really need a set of hands and eyes to help me figure this out. I don't think this is a "simple" problem, but it's apparently too much for me. I'll check the fuel hoses, vacuum lines, etc... again this weekend...

[detroiter]

Hi azasadny,

There's a retired Big 3 engineer who is very familiar with CIS in Windsor, ON. I'm sure it will be OK with him, but let me call first and check if it's OK for you to call him.

I will PM you when I hear from him.

Randy P
Windsor-Detroit

[IROC]

You should add another selection to your poll that says, "Take it easy on him - we've all been there."

Throwing new parts at a CIS system is a frustrating method of trouble-shooting. If it "ran great last Sunday", you can't be too far from it running great again.

One thing to check is to make sure everything that you replaced was hooked up correctly. A loose wire here or there could be the problem...

Good luck,

Mike

[bigchillcar]

Art,
Damn! I wish I was still an Ypsilanti-based pilot! I lived in Detroit for a year back in '99. Big change coming from Florida. Anyway, wish I could have helped more. I'll take my Bosch book in to work today and at least try to come up with some more helpful suggestions. When you don't work on this system everyday, it doesn't take long to forget. It seems whenever I have a CIS problem, I study long enough to become an 'expert', I solve the problem and then forget how I did it a month later!
Hang in there, this board's too proud not to send some cavalry!
Ryan

[mr914]

Azasadny,

I have a '74 with CIS in the Clarkston area.

I have 2 complete spare CIS setups.

Are you near Taylor-tucky?

Depending on weather I may be able to give you a hand.

PM me for phone numbers

[azasadny]

mr914,

I'm in Wyandotte, about 4 miles from "Taylor-tucky"! I'm near the Detroit River... (5 blocks away)

[zenodog]

azasadny,

I'm going to be out of town for the weekend, but my friend Robert will be around and he has the CIS guages. He has a fair amount of CIS experience working on Audis and VWs. I'll PM you with his phone number. He lives up in Ferndale. He has been known to work for beer. Call him up maybe you two can work something out. Good luck.
-Aaron

[azasadny]

Well,

A fellow "Pelicanite" came over this AM to try and help me figure out why my car won't start and we did the following:

1. Confirmed that we have spark at plug #1
2. Confirmed that we have fuel at the injectors
3. We towed the car and popped the clutch in 2nd gear and the car started, popping and backfiring the whole time and when I pressed on the gas pedal, the engine immediately died.
4. We sprayed starting fluid in the airbox and it still wouldn't start.

Could a "bad" cold start valve cause this. Any suggestions as to what to do next?

[fredmeister]

You should check to see that the thermo time switch wiring is intact before going after the cold start valve. Make sure that the connections are clean and both tight on the little terminals in the drivers side chain housing cover.
The cold start valve may be the culprit. Is the fuel pump pressure ok....could be a bad fuel pump relay or a bad pump.....mine failed last summer.
The CIS gages will tell you alot. Did you check the pop off valve inside the intake housing to make sure it is not leaking or open? Provided you have a pop off valve installed. Is the air box cracked? The fact that it popped and backfired in second gear may have damaged the air box. If it is cracked it will not run and will be really lean if it does!
Is the timing set properly? Severely advanced timing will cause the same problems....and the distributor shaft is known to stick and not allow the centrifgul advance weights to return freely unless lubricated on a periodic basis. My 79 911SC distributor had to be rebuilt twice for this same problem. I now make a habit out of lubricating the shaft under the little felt pad when the rotor is removed.
Check all these little things first before a massive replacement campaign begins. Timing will be hard to set without the car running, but you should be able to see if the advance plates are stuck on the distributor by feeling for rotation when grabbing the rotor and rotating it back and forth a little.
Good luck.......don't give up no matter how frustrating it gets.....I know the feeling.

[azasadny]

I just discovered that my Cold start valve and Thermotime switch aren't getting any power when cranking the engine. I used my circuit tester and confirmed that there's no power on that circuit. Since all of the original wiring is long gone, tracing the wire will be a pain, but I'll do it right now. I'm colorblind, which doesn't help. Someone gave the me "this goes to there" description of the cold-start valve and thermotime switch, so I'll have to follow that.

Thanks for the good advice and encouragement guys!!!!!

[azasadny]

I replaced the cold start valve and thermotime switch last summer when the intermittent cold start problem began. Today, I was able to get the car started after replacing a wire splice from the throttle microswitch to the solenoid (old wire was in ver bad shape). After driving the car about 15 minutes, the car started easily, after sitting 1 hour the car will not start again. I'm back at "square one" and I only hope I can get the car started again to drive it to the shop and let a "professional" look at it since this problem is obviously beyond my meager abilities. Thanks for your advice, I've gotten lots of good advice, I just can't get the "root cause" of this problem resolved!

[azasadny]

I took the car to a local mechanic and he's had the car for two days. He checked and found several "small problems" (leaky injectors, loose connections, etc...) but he tested the WUR and he got "bad results" which leads him to believe the WUR has failed and needs to be replaced. He's going to get a Bosch remanufactured unit and swap it to see if this fixes my cold-start problems. If the car (after being warmed up) sits for more than 20 minutes, it is very difficult to restart and a cold start is incredibly difficult. I really hope this is the "root cause" of my problems...

[Schuey]

keep us posted, I'm new to the CIS as well and feel for you...best of luck

[ruf-porsche]

Originally posted by azasadny
I took the car to a local mechanic and he's had the car for two days. He checked and found several "small problems" (leaky injectors, loose connections, etc...) but he tested the WUR and he got "bad results" which leads him to believe the WUR has failed and needs to be replaced. He's going to get a Bosch remanufactured unit and swap it to see if this fixes my cold-start problems. If the car (after being warmed up) sits for more than 20 minutes, it is very difficult to restart and a cold start is incredibly difficult. I really hope this is the "root cause" of my problems...

I think that your cold start problem is the leaky injectors. Leaky injectors or a bad check valve does not allow the system to retain the fuel pressure within the lines.

It could be that the leaky injectors may leak enough gas into the intake manifold that when you try to start the car, the plugs get wet, and with wet plugs you will never start the engine.

The WUR may also contribute to the COLD start problem, but if you drove the car and let it sit for 30 minutes, the engine should still be warm enough that the WUR does not come into play.

When you start your Porsche, do you let the fuel pump run for a while or do you try to start it up immediately? If my Porsche has been sitting for more than a couple of days I generally let the fuel pump run for about 30 seconds before trying to start the car.

[azasadny]

ruf-porsche,

I always let the fuel pump run for awhile before I start the car. The mechanic didn't say how bad the injectors were leaking. Can they be cleaned or does this usually require replacement of the injectors? Thanks!

[azasadny]

I guess right now the cold start problem is due to one or more of the following:

1. leaky fuel injectors
2. bad Warm up Regulator
3. any other related components

I'll post the results when we figure it out! Thanks for the helpful advice and assistance!