83' sc cold start ignition problem
 

Hi Guys,

I have long standing problem with my Sc 83, I have it for 2 years and been the same .

Upon cold start I need to turn the engine twice/three times
before its fires up.

The Car is well maintained/serviced, havingh done 131k its featuring new vacuum hoses (samco), stainless steel heat exchanger, exhaust, air tight air-box too ( a year ago split I'd , too much throttling upon cold start....bang! $600 lighter , i'd stuck in a $23 pop-off valve ..Don't want to go there again and just want to isolate the root of the problem for the multiple turning.

The hot start is spot-on first time roound startup..text book.

Any pointers/fixes would be much appreciated.


Cheers.

Jaz

Could be a faulty check valve at the fuel pump or leaking fuel accumulator. If you check your fuel pressures and find that the system does not hold pressure after shut down, then the check valve is suspect.
Also, on cold starts, you should get an immediate firing of the engine (though maybe not continuous running) from the cold start injector. It's possible the injector is malfunctioning and the engine is "waiting" to get fuel from the system pressure.

Thanks Ossiblue, where can i find the cold start injector?


Regards, jaz

Sounds like his problems are with cold-start, not hot, so, rule out check-valve and Accumulator.

Jaz: You'll need the Bentley SC Repair Manual.

For cold-start problems, check these circuits:
There are 2 yellow wires on the Starter Solenoid.
One is for the cold-start-circuit, the other is coming from the ignition key and energizes the Solenoid when starting.
ONLY during cranking, the 2nd yellow wire energizes the Cold Start Valve (CSV) which is controlled by the Thermo Time Switch (TTS) located on the left chain cover.
CSV is blue in colour and located behind/below the Throttle Body (TB), hard to see or reach.
Aside from an electrical connection, it has a thick vacuum line going to it which is coming from the AAR.

The real suspect here IMHO, is the Auxillary Air Regulator (AAR)

Check the AAR located on the right side of the engine between 5-6 intake runner.
It's the item that has a small electric plug and a large vacuum hose connected to it.
Open the clamp holding the outside-hose.
Pry it off with the screwdriver just enough to get it out of the way so you can see into the opening.
Don’t worry about the Alu pipe; it’ll move enough.
With the help of a small mirror and a light, peek inside the AAR.
When COLD, you should see an opening in the slide shaped like a half-moon.
When HOT, the opening is completely closed.
If it isn't closed, the AAR is either kaput or doesn't get any power.
You can spray some WD-40 into the valve in case it is just sticky.
To check the power, carefully open the tiny clip on the plug with a very small screwdriver and pull it off.
The wire clip is tricky but necessary; don't yank it off.
Start the engine and check the plug for 12 V.
(One wire is power, the other (brown) is ground)
If all is well, replace the hose and clamp securely.
Let me know if the AAR works HOT and COLD.

Get the Bentley. :)
And no pumping the gas when starting. :(

Very sound advise.......
 

Jaz,

Gunter has given you a very sound advise in troubleshooting your problem/s. But if you prefer to do the electrical tests for FP/AAR/WUR without having to run the engine, simply use jumper-wire with in-line fuse between terminals 87a & 30 (fuel pump relay socket) and turn the ignition switch to ON position (not start). This procedure will mimick a running engine with regards to fuel pump, auxiliary air regulator, and warm-up regulator operation.

Tony

Gunter & Tony ....Thank you,

Gunter I will try the AAR approach first and report back.
Regards, Jaz

Quote:
"If you prefer to do the electrical tests for FP/AAR/WUR without having to run the engine, simply use jumper-wire with in-line fuse between terminals 87a & 30 (fuel pump relay socket) and turn the ignition switch to ON position (not start). This procedure will mimick a running engine with regards to fuel pump, auxiliary air regulator, and warm-up regulator operation."

Good stuff, Tony. :)

This way one just has to disconnect the plugs and check for power without having the engine running.

not likely the AAR, that comes into play after it is started. besides, putting his foot on the gas will do the same thing as the AAR.
plus, the aux air valve (AAV) gives it a good dose of air while starting, hot and cold.
most likely it is in the CSV circuit. if that is good i would then look at the cold control pressure (CCP). plugs/tune up?

Hi Guys,


Finally got round to test using your advise and subsequently FIXED the problem.

When COLD: I'd removed the vacuum hose to the AAR, and noted the AAR neck had a thick oil deposit (butter consistency) , and also noted the opening into the AAR had an oblong notched-opening on the plate and not a half-moon opening. I'd used cotton-bud-Qtips to clean up and sprayed liberal amounts of WD40 behind and in-front of the notched-opening plate. Then put the vacuum hose back on, and successfully started it on first crank/key turn.

Just to be sure: - When HOT (let the car warm up for 5mins), I'd removed the AAR Vacuum pipe to view the plate position , noted it was competely closed and then over a course of a few minutes it was slowly opening to reveal the oblong opening at the edge.


Thanks Guys.


Cheers, Jaz

Always corrected if I'd spray WD40 into the AAR aperture (cold start) and starts immediately.

On subsequent mornings it back to multiple cranks again

Any clues?

Jaz

Jaz,

Does your SC have a vacuum retard distributor (two hoses to the vacuum module).

Paul

Sounds like the WD40 acts as "fuel" and this is why your cold-start behavior got so much better. WD-40 is a blend of very light oils and has a pretty high vapor pressure.

I would check the cold start injector and the circuit to it. It is a fuel injector much like on modern cars that is activated by +12 volts. It is on the same circuit as the starter. So every time you crank it squirts fuel into the intake.

If memory serves it is mounted to the throttle boddy bottom facing the firewall of the engine. So it is a little hard to get to.

Ingo

cold hard starts = cold start valve (CSV), and circuit. cold control pressure. that is with hot starts ok and it runs good once wramed up. if it runs ok cold after it starts up, i would look at the CSV first. if the CSV is good, it will fire up then die.

the DW40 is acting like a fuel, as said above.

turn the key on, lift the sensor plate for few seconds, cold, i bet it ifres right up.

The vacuum retard distributor has a single hose into the vacuum module.


I will focus in on the cost start valve and check the 12v voltage into it next.



Thanks

Jaz

The CSV only gets power if the TTS allows it depending on temperature.
When turning the key to start, the second wire on the Solenoid sends power to the CSV but if the temperature of the TTS is past the threshhold, the CSV will not squirt.
The TTS is mounted on the left chain cover.
The CSV is very hard to reach and the electic plug has a small wire clip on it; PITA.

Before going there, I'd check wiring to and from the Starter Solenoid, CSV, TTS, WUR and ensure that power can indeed reach those components as needed.

If the wiring looks good, maybe take the plug off the CSV on a cold morning, attach a test light to the plug, have someone crank the engine and see if you get power for a few seconds.
Disconnect the CDI module to prevent engine-start!

The Bentley SC Repair Manual page 970-11 shows the circuit for cold-start.

the TTS provides a ground for the CSV. one wire has power when the key is on, the other (red/blk ?) has power from the CSV like gunter said. may be easier to check at the TTS. pull the wire off of course. you could also try grounding the CSV wire and see if it starts.