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Discussion Starter · #1 ·
Hi all,

I have a starting issue with my Silver Shadow. It has been off of the road for a little while as the brakes needed some work on the high pressure hydraulics. Once reassembled with new plugs, plug leads, points, condenser and clean of the carbs the engine started and ran ok.

But now i started the car at the weekend and it ran for a couple of minutes and then stopped.
I have checked that there is a spark at the plugs and put in a new coil
I have checked the fuel pump and that appears to be running ok to prime the system
I have made sure that the carberetter float chambers have fuel in them

Now it cranks but will not start.

The timing must be reasonably ok as it ran before.

I dont know if its of any relevance, but i did prevoiusly get a bolwn fuse Number 12 - for the ignition and fuel pump ( i assumed it was caused be bad earth connections to the fuel pump).
Also, it did backfire once when tring to start

Does anyone have any ideas where to start as i have tried all I can think of at the moment

Thanks
 

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Hi Leigh

Could be many things so I will start the suggestions.

Is your car a series 1 or 2 - what is the chassis number?

If it's a series 2 check the oil pressure switch is not faulty - the car will not run if it detects no oil pressure.

Is the distributor clamped tightly - if it's moved the timing will be out - worth re-checking timing anyway.
 

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The fuse blew because the components on that circuit are demanding juice. Make sure the fuel pump is not overworking due to a clogged fuel filter located before it. Clean the electrical connections while you are there. Sometimes fuel problems are caused by electrical issues. Clean grounds are just as important and clean every one you see going forward.
Did you change the inlet filter at the carbs, clean the float chamber, check to see if the floats actually "float", set the float height, etc?
 

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Discussion Starter · #4 ·
Hi, Thanks for your replies.

My car is series 1 I think.
1972 chassis no. SRH13450

So I guess it does not have a oil pressure switch?

I have checked the distributor an set the timing static as best I can. just as I have done previously and never had a problem.

Cleaned all connections to the fuel pump and made sure good connections to the coil too.

The fuel pump is quite new (about 2 years old) and can hear ticking it when the key it turned on, pumping the fuel through. and hear it stop when the system is charged with fuel.
I did not change the filters in the carbs, but the seem to be working ok and fuel passes through. The float chambers fill with fuel and yes the floats have been adjusted and they do float.
 

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If the carb filters are clogged, they do pass fuel, but will not keep up with the burn rate when the motor is running, so it will initially run.
You have to throw everything on the board and eliminate and you will find the cause.
Your car is a Series I. My first RR was a 1972 SRA-14704
 

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Discussion Starter · #6 ·
Ok.
I can change the carb filters, but i assumed that if they were a problem then fuel would not make it to the carb inlet, which it does.
Also would it not try to fire at first? Where as it does not fire at all.
I shall change them and come back and let you know if there is any change.
 

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Here is a simple step by step test procedure that I have posted previously that will narrow down the fault: Substitute points and condensor for module which is what your model should have unless you have installed an electronic ignition.

First thing to do is to check for spark at a plug lead, then spark at coil lead. If spark at plug lead (at spark plug end) then you have fouled plugs or a fuel issue. Remove plugs to check for fouling. If no spark at plug but spark at coil lead - rotor is faulty. If no spark at plug and no spark at coil lead - coil or module faulty. To determine which, attach a 12 volt test light to negative low tension terminal of coil. Have someone crank over the engine, if light flashes quickly the module is working trying to fire the coil - coil is faulty. If light doesn't flash the ignition module is faulty. These tests are assuming you have confirmed there is power at the positive low tension terminal of the coil.
Also to confirm a rotor is faulty, remove cap, remove coil lead from cap, hold end of coil lead to within an eighth inch of the centre of the rotor with gloves or insulated pliers. Have someone crank over the engine. If the sparks jump to the centre of the rotor the rotor is faulty. A spark SHOULD NOT jump to the rotor if it is good. Rotors can function fine when cold, short out when hot, and have intermittent symptoms. We see faulty rotors fairly often, especially aftermarket ones.

Another fault if you have good spark at plugs could be a malfunctioning weakener system. To eliminate that system from the equation simply pull the weakener hoses off the carb float bowls so they vent to atmosphere.

If it backfired once that usually indicates a faulty ignition module, on cars after VIN 22118 which are fitted with Lucas Opus electronic ignition. A backfire on models previous to that with points and condensor usually indicates a failed condensor.
 

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Hi Leigh

Yes, your car is a Series 1, as is mine, so it will not have the oil pressure cutoff.

Have you got all your air intake ducts fitted. From cold if the two U shaped ducts that attach to the carbs are removed, then the engine can be hard to start as there is no choke. If you have got them fitted, pull back the duct that runs from the air filter to the central plenum and check the choke butterfly valve is closed.

Also, make sure your air filter is not blocked.
 

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Discussion Starter · #9 ·
Dounraey,
Yes the U shape ducts are in place and the butterfly valve us closed. the air filter duct is off at the moment, so not a problem with blocked air filter.
 

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Discussion Starter · #10 ·
Hi Jim,
I have a good spark at the plug and also have tried with the hoses disconnected from the carb float bowls.
I will check through it again as you suggest.
I have another set of points and condenser, so will swap them too and see if that makes any difference.
 

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If the condensor is bad the spark at the points will be yellow and bright, if condensor is good the spark will be blue and small. Make sure the spark is regular and not intermittent. Check plugs also to make sure they aren't wet.
 

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Wow - this is a tough one.

Could your fuel have been contaminated. Has the car been standing outside for a while - maybe water has got into the tank. Also, old petrol can cause starting problems. I'm grasping at straws here. Will be interesting to see what the cause is when you find it.
 

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Discussion Starter · #13 ·
Wow - this is a tough one.

Could your fuel have been contaminated. Has the car been standing outside for a while - maybe water has got into the tank. Also, old petrol can cause starting problems. I'm grasping at straws here. Will be interesting to see what the cause is when you find it.
Nope, the fuel quite new and its in a garage all the time (especially at the moment).
I could drain it out and refill and see if it makes any difference. At least that way I will know it's definitely not a fuel quality issue.

Yeah, its is a tough one. I will keep you posted with any progress, slow as it might be.
 

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Your answer is within the "fire triangle"; Air, Fuel, Ignition. You'll find it, and the journey is both educational and frustrating to a point.
 

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Discussion Starter · #15 ·
Hello,
Your not wrong about the frustrating part :)

Today I have insalled a different battery today (barrowed from another cat i have) and checked the spark at the plug, which looks blue and small to me. I have checked the plugs which are not fouled.
There does not appear to be any issues with the distributor or coil that i can tell.
I have disconnected the hoses from the carb float bowls.
I have checked the fuel pump connection, and they are good
I have tried to start it, and it sometimes seems to be attempting to start, but not enough to get it running.
I have tried to start and rotate the distributer a little (as i have done previously) incase the timing has become out.

My guess is that there is a fuel issue.

I am yet to change the filters in the float bowl lids, so will try this and drain the fuel tank and replace with fresh fuel and then try again.

Any thoughts?
 

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Replacing the small carb filters sounds like a good next step. Check inside the filter bowls for crud and clean out if necessary. It might help if you spray some carb cleanerr in there in case the inlet valves are stuck.
 

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Spark is blue and small as Jim says.

Unlikely it suddenly fell out of ignition time, unless the distributor came loose some how or the things that drives it fell out of time.
Both scenario's are very unlikely to happen.

When you remove the float bowl lids, check that the float bowl check valves are clean and working.
Check for sticking pistons in the dash pot.

Check floats for cracks, they SHOULD NOT be filled with fuel.

As others mentioned, it's acting like there is dirt (rust) in the fuel flow.

If there are rust particles at the bottom of the float bowls, then the feed from the float bowls to the main jet also may be partially blocked.
Take some carb or brake cleaner in a spray can with the long plastic spray nozzle and squirt it in the orifice at the bottom of the float bowl, it should spray freely out the main jet.
Watch your eyes, have a rag handy and notice if there is any rust debris.
 

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Spark at the POINTS should be blue and small, if bright yellow then you have a bad condensor. Set the timing statically and check once running with a timing light. If you are getting a steady blue spark at a couple spark plug leads then you are correct to look for a fuel delivery issue. Confirm you have fuel flow to the float bowls, remove the filters at the float bowl inlet and clean or replace. . Note: If you use a GM carb filter you must remove the rubber plug in the end of the filter for it to work on a Shadow.
 

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If you have spark at the plugs and fuel and air this little Roller not only should run, it has to run. I would check the compression to see if something has changed there. Also king wires and spark plug wires can cause intermittent start and run conditions . One more thing. I recall a resister on the firewall near the distributor. This can be intermittent along with the connector that fits into it. Check these. Good luck.
 
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