"Missing" cold-start parts!!

[azasadny]

Help! I'm having cold-start problems and discovered yesterday that the hand throttle on my 1974 911 with 2.7 and CIS isn't connected to anything! Evidently, there is supposed to be a plastic part that connects the hand lever to a rod that connects to the throttle. I need to get the part.... While I was troubleshooting I also found that I was "missing" the cold start relay in the rear electrical shelf and put a relay in. The middle fuse in the rear only has one beige wire connected to it and I believe that is the fuse for the cold-start system, but I'm not sure. Where do the wires from the WUR go? I have an orange "ground" wire that connects to the manifold and a beige wire that goes to the middle fuse in the rear fuse panel. Is that correct?

I have a difficult time understanding the wiring schematics in the books, does anyone have a wiring diagram for the rear engine compartment, covering the 3 fuses and their connections? I'm going to buy a multimeter tonight so I can find out if I'm getting any current at all to the thermotime switch, cold-start valve and the WUR. Any other suggestions?? Thanks!

[Early_S_Man]

There is no relay in the 1974 cold-start circuit!

Yellow wire from Tetrminal 50 on starter solenoid goes to microswitch ...

Yellow wire from other side iof microswitch goes to Terminal 'G' [heater element] side of ThermoTime Switch ...

Gray/White wire leaves Terminal 'G' of ThermoTime Switch and goes to one side of Cold-Start Valve ...

Red/Black wire goes from Terminal 'W' [switched ground contact] of ThermoTime Switch to other side of Cold-Start Valve ...

That all!

[azasadny]

Warren,

Thanks for the clarification. Just to make sure I understand what I'm doing...

1. Where is the "microswitch? Is it attached to the side of the throttle body?

2. Is the starter solenoid located near the starter underneath the engine? Do I need to go under the engine to see it. If so, I'll jack up the car tonight.

3. Is the "middle" fuse in the engine compartment used?

4. Do you have any diagrams that show the wiring, this stuff is very hard for me to visualize.

5. Sorry to be such a pain!!!

[dhoward]

Hand throttle control lever, Part #901-424-317-00
$23.69 at my dealer.

[azasadny]

I tried a few things last PM. I checked my wires to/from the WUR and there is a ground wire to the engine shroud bolt and a beige wire going to one side of the middle fuse in the rear fuse carrier. I tried lifting up on the lever under the fuel distributor in the airbox to see if I caould coax the car into starting, but no luck. I did notice a slight hissing sound coming from the CIS unit after trying to crank the car, is that normal???

[McDaniel]

The plastic part you are speaking of was broken in my '74
2.7.
Got one from Pelican about...?Can't find invoice...but about $15-$18

[azasadny]

McDaniel,

Thanks, I have the part ordered. I appreciate your help!

[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?

[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 very 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...

[azasadny]

I wanted to give you the “final update and root cause resolution” for the cold start problems I was having. The warm up regulator (also known as WUR or pressure control regulator) was bad and had to be replaced ($329.00 for new Bosch part) and 3 hours of labor to troubleshoot fuel system, CIS, ignition, wiring, install WUR and readjust mixture, idle and pressure, for a grand total of $558 (including tax). The car was in the shop for 8 days and starts easily now. I still need to fix the hand throttle and the part I need is on order. All in all, I’m very satisfied with the quality of repairs and I believe the 3 hours labor charge to be very reasonable considering the fact that the wiring was in such bad shape. I could recommend the shop and I’m glad I’ve found a place where I can take the car when I’m in over my head and need a professional to take a look. Thanks for all of your help, I really appreciate it!

[azasadny]

The original starting problem has returned. I managed to start the car after about 50 cranks and several loud backfires, then it started and ran great. I drove it about 60 miles to a Porsche event and I stopped at a gas station. Restarted the car with the first crank. After letting the car sit for 30 minutes, it's extremely difficult to start again. I'm goint to test the pressures using my recently acquired gauges. I'm going to search the PP archives for the testing procedure and take it from there. I'm not going to start replacing parts again and evidently my mechanic didn't fix the problem, so I don't think I'll be taking it back to him.

[McDaniel]

CIS problems (if indeed that turns out to be your problem)
are very difficult to identify and fix. Too many wrenches IMHO
go for replacement of parts too quickly. No suggestions for
repair, except to use the computer repair rule...fix or attempt
to fix one at a time. Only add one part at a time.
Good Luck!
I took my '74 out for test runs yesterday and it pulls strong...
great feeling after 9 years in storage and rebuild...

[azasadny]

McDaniel,

I agree 100%. What is so frustrating is that when I eventually get the car started, it runs great! I put 200 miles on it yesterday and the car ran flawlessly. It started right up when I sprayed starting fluid in the airbox, which leads me to believe there isn't enough fuel at startup. I'm putting in a check valve at the fuel pump this week but first I need to use up the 5 or so gallons of fuel in the tank. The WUR was replaced which improved things, but I still have a problem. I'm looking forward to turning the key and hearing the car start!!!! Thanks!

[ruf-porsche]

Hey Azasadny

You 74 should have the fuel pump in the rear and not in the front. It looks like the PO might had relocated the pump. If you can you should check the number on the fuel pump before order the check valve. He might had use a later fuel pump.

What did your mechanic do with the injectors that were leaking? Did he clean and tested them before reinstalling, or did he just replace with new injectors?

Hopefully you will get this all sorted out. I know when I had my 74 it always started fine except when the fuel pump went out.

[azasadny]

Ruf,

Thanks! My mechanic cleaned the injectors and replaced the WUR. That "fixed" part of the problem because before I couldn't start the car even when I sprayed starting fluid into the airbox. Yesterday, I was able to start the car easily once I sprayed starting fluid into the airbox. The car won't start "cold" or "warm", but starts "hot", meaning if I turn the car off for more than 30 min, it acts the same way as when it's cold and it takes 20-30 cranks to eventually start.

I thought the fuel pump was at the front of the car, just behind the fuel tank. I have not crawled under the car to find it. If the fuel pump is in the rear, whereabouts would it be? Someone else once said theirs was "behind the driver's seat, under the car". The parts diagram for the '74 looks like the fuel pump is in the front, I'm afraid I'm confused...

[ruf-porsche]

Originally posted by azasadny
Ruf, I thought the fuel pump was at the front of the car, just behind the fuel tank. I have not crawled under the car to find it. If the fuel pump is in the rear, whereabouts would it be? Someone else once said theirs was "behind the driver's seat, under the car". The parts diagram for the '74 looks like the fuel pump is in the front, I'm afraid I'm confused...

If you still have the original fuel pump for a 1974 911 it should be at the rear by the driver side wheel. If you do decide to replace the pump, buy a new one, don't buy a remanufacture one. I try the remanufacture route and the pump was leaking gas so badly that I sent it back for a new one.

Becareful with removing the pump,it is mounted with rubber isolation mounts, use plenty of penetrating oil.

[azasadny]

Ruf,
Thanks for the advice. I'm going to replace the check valve on the fuel pump one night this week. I just got back from a nice, spirited drive (to burn off gas so the tank will be as close to empty as possible). Any excuse I can get to drive on a beautiful evening is OK with me! I'll let you know how it goes, thanks again!