Helpp......Starting problems 911sc

[T77911S]

may be a clogged screen in the WUR, bad pressure, wrong mixture setting, air leak.
if you are pushing up on the plate to make it run then first, high control presure(clogged screen or just bad WUR), or the mixture is too lean.

[Alan L]

I would second Gunters advice.
Another option may be to hold the plate steady til it runs and then tweek the adjust screw - a 1/4 turn either way should be plenty to see a change. 1/4 turn almost takes you from too rich to too lean. Open the idle screw a turn or two.
The starter solenoid problem usually starts intermittent, before it fails to go completely.
My guess is you will have the same problem another day - not to far away.
Next time you take it out, pull the solenoid apart and clean it up.
Alan

[black 911sc]

I think I am going to drop the engine (for the 3 time) and check for any air leaks.
The drop is easy because, I have a car levée bridge

The first time a put the engine in it was running fine, must by a small thing that's not good.

[Gunter]

By air leaks you mean vacuum leaks?
To check for vacuum leaks, the engine must be running.

[Alan L]

Dropping the engine because it wont run is a bit drastic.
Your best chance is while it is in and hooked up to power and fuel.
Start diagnosing - fuel - spark etc.
Alan

[black 911sc]

I must now all the basic checks before I drive another 40 km.
I have check several topic's here fore the basic checks.

The FP, FPR and wiring are ok.
Spark (plugs) ok
injectors ok
Ignition ok

Can anyone give my the complete list of checks with specs how to check for example, the WUR CSV, enz.

[Gunter]

Since you do a lot of work yourself, why not get the Bentley SC Repair Manual?
It has a lot of info on how to test the components and troubleshoot; you"ll love it!

For problems with cold-start, the WUR, AAR, AAV, Thermo-timer, CSV, Deceleration Valve............are suspects.
The Bentley shows you the right terminology and how to test.

[Alan L]

If you have managed to repair the head leak yourself? you have enough experience to find the problem.
You wont be driving 40 km if it wont run for more than a second.
Is it starting, or not?
Do you get fuel pressure on the airplate?
FP, and FPR OK? - what are you particularly refering too.
Is the only symptom you can desribe a 1 second start. Each and every time, or will it not start at all now. Or are you driving 40 km in it?
Alan

[black 911sc]

Alan,

My porsche is stalled 40km(single) far away in a garage.

What I meand is, I must drive every time whit my car (VW Passat) to the garage and check for things that are proberly wrong, then back home again.
I am doing that for the last two weeks now, and still the Porsche runs for only one second......

I am going to buy the Bentley SC Repair Manual.

I have the Manual from this site.

http://www.cannell.co.uk/Manuals.htm


Alan,

Is the only symptom you can desribe a 1 second start. Each and every time.

Yes, each en every time 1 second start, I will run by holding the airplate stedy.
But then I runs not good en popps every time.

[T77911S]

i would still check the control pressure before an engine drop

[black 911sc]

Friday I am going to my Garage where the 911 is stalled.

Then check some things again.

[black 911sc]

Friday I am going to my Garage where the 911 is stalled.

Then check some things again.

Her's a picture of my new rebuild engine.

[black 911sc]

Originally Posted by black 911sc

Friday I am going to my Garage where the 911 is stalled.

Then check some things again.

Her's a picture of my new rebuild engine.

and my car.

[T77911S]

beautiful

[Gunter]

Very nice.
I would concentrate on manipulating the mixture and fast idle to get it running.

There is a small screen inside the WUR that sometimes gets dirty.
Remove the line on top (One wrench to counter-hold the nipple and one to open the cap-nut)
Remove the nipple, look inside. You should see the tiny screen.

Check the AAR (It is mounted between #5 and 6 intake runner and has a plug for power plus large vac hoses) The AAR is important for cold-start.
When cold, open the clamp on the large outside hose, pull the hose off just enough so you can see inside.
Use a light and a small mirror.
You should see an opening in the valve like a half-moon.
This opening closes when the engine gets hot. (The AAR has a heat element inside that gets 12V from the plug)
So, open when cold, closed when hot when working correctly and getting 12V.

[black 911sc]

I went today looking for a pressure gauges.
It cost here in Holland $150 a $200,-....

I am going to try make one myself.

[Alan L]

You can make your own for about $50.
You need a 100 psi gauge, and a switch off valve, plus the plumbing fittings to hook into WUR line.
You break into the system at the WUR exit to the fuel head - so you need a male, and female of this union.
Alan

[black 911sc]

I am just back from the garage where the porsche is stalled.

If check serveral things:

-WUR
screen cleaned. measering with the ohm meter, bitmetal is ok
Not check the fuelpressure (did not have a gauge )

-Thermal Valve.
removed and plugged on the 12v, after 30sec it's open.

-Auxiliary air valve
does open, hoses removed and look with a mirror and flashlight in it.

-thermotime switch.

It's halve closed when engine is cold, This switch allows operation of the cold start valve at engine temperatures below 45 degrees.
I removed the thermotime switch and heated it, the thermotime switch bimetallic strip, which interrupts the current flow on the ground side of the cold start connection failed and did not switch off.
Must have a new thermotime switch, but engine must run with this thermotime switch, only when engine is warm it faileds.

-Fuel pump gives approxle 1litre after 30sec's.

-Vaccum leaks.

I found out that the airbox is cracked (where the 6 intake tubes are coming together, i fix it after the first backfire)

so that must be it.

when not..... its the fuelpressure.

next friday the engine will be dropped

[Gunter]

Cracked airbox will give problems for sure.
For repair, we have an epoxy here called: JB Weld.
It comes in 2 tubes, one is a hardener and you have to mix them together 50/50.

Quote:
"-Auxiliary air valve
does open, hoses removed and look with a mirror and flashlight in it."

To be sure: It has to be open when cold but completely closed when the engine is hot.
The opening depends on the temperature: If it's really cold, it shows almost completely open.

[Alan L]

Not sure precisely where your airbox is cracked- but if it can allow air into the intake fuel mix without going past the airplate, you will have a lean mixture. Enough to cause your symptoms.
Alan