Cold start issue

[dave123456789]

Hi all.

Having issues with my 1982 911 SC.

Really hard to start. when starts idle fine but if I press the throttle it will die unless I really feather into it. If i leave it idling it will often stumble and die as well. When warmed up seems to not have an issue.

Done a pressure test.
cold control pressure 1bar
warm control pressure 2.5bar after 4 mins - peak 2.7bar
system pressure 4.5bar
residual pressure is fine - just starts from 2.5 but its still 1.2ish bar after 20 mins.

WUR is an 089 model

All pressures seem low. Where do I start? Google is leading me towards just rebuilding the WUR but wanted to see if anyone has any other ideas.

Thank you

[Dripola]

Your pressure readings look fine for an 089.

[dave123456789]

Well now I am even more confused. I am unsure what temp the WUR was when testing but ambient temp was about 10 degrees in the garage (unsure if WUR was any differnet) so 1 bar would be on the very low side. Also my test was without vacuum.

Looking at your data there I am at the extreme low end for all readings.

[Dripola]

I got the pic from another pelican, I was working through fuelling issues last weekend. I believe it’s official Porsche specifications for that WUR.

The Low pressure would give you a better start (rich), wouldnt result in the issue you’re having. you could check your cold start valve or your AAR.

[dave123456789]

Originally Posted by Dripola

I got the pic from another pelican, I was working through fuelling issues last weekend. I believe it’s official Porsche specifications for that WUR.

The Low pressure would give you a better start (rich), wouldnt result in the issue you’re having. you could check your cold start valve or your AAR.

Thank you I will test both those components tomorrow after work and see if they are the cause

[boyt911sc]

Dave,

Is the motor in your car a US spec SC or a RoW? Without knowing which motor you have in your car, we will be just guessing. Keep us posted. Thanks.

Tony

[dave123456789]

Originally Posted by boyt911sc

Dave,

Is the motor in your car a US spec SC or a RoW? Without knowing which motor you have in your car, we will be just guessing. Keep us posted. Thanks.

Tony

It’s a right hand drive so would be RoW.

[Schulisco]

First and foremost: Check for vacuum leaks, only with a smoke generator. Brake cleaner, cigarette smoke is nonsense and ineffective.

Then:
* Check the ignition timing (suppose the ignition wires, spark plugs and rotor and rotor cap are in order)
* Check the the thermotime switch (controls the cold start valve, it is located on the left chain cover, the CSV is located in the bottom of the airbox on the backside)
* Check the for fuel leaks within the system, esp. fual accumulator and check valve (at the fuel pump)
* Check the mixture if the engine does not run either too lean or roo rich

Thomas

[boyt911sc]

Originally Posted by dave123456789

Hi all.

Having issues with my 1982 911 SC.

Really hard to start. when starts idle fine but if I press the throttle it will die unless I really feather into it. If i leave it idling it will often stumble and die as well. When warmed up seems to not have an issue.

Done a pressure test.
cold control pressure 1bar
warm control pressure 2.5bar after 4 mins - peak 2.7bar
system pressure 4.5bar
residual pressure is fine - just starts from 2.5 but its still 1.2ish bar after 20 mins.

WUR is an 089 model

All pressures seem low. Where do I start? Google is leading me towards just rebuilding the WUR but wanted to see if anyone has any other ideas.

Thank you

Dave,

Where are you located? Was the motor running when you did the pressure test or just the FP running? Do not touch the gas pedal to start a fuel injection motor. Just put the gear in neutral, hand brake on, and turn the ignition switch to START. I don’t even get into the car. Reach through the open window and leave the gas pedal alone. Thanks.

Tony

[dave123456789]

Originally Posted by Schulisco

First and foremost: Check for vacuum leaks, only with a smoke generator. Brake cleaner, cigarette smoke is nonsense and ineffective.

Then:
* Check the ignition timing (suppose the ignition wires, spark plugs and rotor and rotor cap are in order)
* Check the the thermotime switch (controls the cold start valve, it is located on the left chain cover, the CSV is located in the bottom of the airbox on the backside)
* Check the for fuel leaks within the system, esp. fual accumulator and check valve (at the fuel pump)
* Check the mixture if the engine does not run either too lean or roo rich

Thomas

I’ll do those and report back

[dave123456789]

Originally Posted by boyt911sc

Dave,

Where are you located? Was the motor running when you did the pressure test or just the FP running? Do not touch the gas pedal to start a fuel injection motor. Just put the gear in neutral, hand brake on, and turn the ignition switch to START. I don’t even get into the car. Reach through the open window and leave the gas pedal alone. Thanks.

Tony

Located New Zealand. Car was running fine prior to this issue.
Test was done with just the fuel pump running