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Jeff Cheng
Prolific User
Username: makeshift

Post Number: 106
Registered: 2-2016
Posted on Wednesday, 06 June, 2018 - 09:33 pm:   Edit PostDelete PostView Post/Check IP

I got SRH23650 back from its annual check with a clean bill of health up a few weeks ago, so I've been trying to make the most of the clear autumn weather before winter sets in. Last weekend was a 60mile drive through the countryside without a hiccup.

Driving home from work this afternoon (7 mile trip), I was rolling along in suburban traffic, everything fine. I coast to a light, and 10sec after I come to a stop, she cuts out (#1). The light goes green, the car starts right back up again and I pull away.

A mile or two later, traffic banks up, and the same thing happens as I come to a stop (#2). Again, starts right back up, but dies again several car lengths later (#3).

This time it took a good few minutes to start again as I frantically wave traffic around me; cranking with a combination of no throttle, full throttle, part throttle until she fires.

One last FTP a hundred odd meters down the road at the next lights (#4), after which she started right back up and drove the remaining 2 miles home without issue.

Now, since it suddenly cut out all at once, I initially suspected ignition heatsoak, but idling the car in my driveway another 15 minutes when I arrived home showed no misfires or faults. After turning off, the lightest flick of the key kicks her back to life.

Spark:
I replaced the Opus module 12mths/1000miles ago with a Flying Spares rebuilt unit, along with a new coil, cap and rotor. This was in response to a 'FTP when hot' situation diagnosed to a faulty Opus unit.

Fuel:
The fuel pumps were rebuilt 12mths ago and filter replaced along with some collapsed lines as required. They tick away as they should (quickly to fill the float bowls, then once every few seconds at idle when heard through a stethescope), so I don't suspect fuel either. Do these cars ever suffer vaporlock? I've idled in much hotter temperatures before.

I haven't been able to replicate the issue since, I've just returned from a 15mile urban drive, and she's been idling quietly in the garage for the last 30 minutes (with adequate ventilation, of course) with no hesitation.

I had just filled the tank to the brim, but that should have no impact on running...

Thoughts?
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Jeff McCarthy
Grand Master
Username: jefmac2003

Post Number: 514
Registered: 5-2007
Posted on Wednesday, 06 June, 2018 - 10:45 pm:   Edit PostDelete PostView Post/Check IP

This happened to SRH20280 a few years ago. The symptoms you describe turned out to be a leaking stove pipe in my case. That's the thin asbestos covered pipe on the nearside that takes heat from the exhaust manifold to the choke solenoid housing just near the centre of the carbs closer to the windscreen.

The leak causes vacuum loss and the stop and go symptoms. The exhaust gases eventually rot the pipe. Replacing it is a pain - you'll need a crowsfoot spanner and patience to get the nuts off the manifold.

My symptoms went on for months before it finally failed completely.

FS sell them but Robert Chapman in Melbourne makes them up and will get it to you faster and no doubt cheaper.
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Geoff Wootton
Grand Master
Username: dounraey

Post Number: 1963
Registered: 5-2012
Posted on Wednesday, 06 June, 2018 - 11:16 pm:   Edit PostDelete PostView Post/Check IP

Hi Jeff

That's a really strange fault given your car is so well maintained. Jeff McCarthy's suggestion is certainly worth checking out. If the stove pipes are leaking the bi-metal coil may be running too cool resulting in choke being partially on.

Another possibility is when you mentioned filling the tank. Was the tank nearly empty before you filled it up. If so, maybe a bit of debris from the tank got through the fuel line and partially blocked a carburetor jet, later freeing itself off.

Lots of possibilities here. Let us know if the fault recurs or if you find the solution.
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Jim Walters
Prolific User
Username: jim_walters

Post Number: 165
Registered: 1-2014
Posted on Thursday, 07 June, 2018 - 03:18 am:   Edit PostDelete PostView Post/Check IP

I also posted this on another forum: I urge everyone to order one of these and keep it in your car in case of an FTP. It will quickly and safely tell you if you have spark at the plugs. It takes the guesswork out of the eternal fuel/ignition fault diagnostic query.



Available here at the exhorbitant cost of $2.48.

https://www.ebay.com/itm/Great-Spark-Plug-Ignition-System-Coil-Engine-In-Line-Auto-Diagnostic-Tester/192177344759?

I have a couple and even for that low price they are decent quality, not nearly what one would expect.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com

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Vladimir Ivanovich Kirillov
Grand Master
Username: soviet

Post Number: 929
Registered: 2-2013
Posted on Thursday, 07 June, 2018 - 06:37 am:   Edit PostDelete PostView Post/Check IP

Jeff, have a look at the fuel itself. It is not beyond some fuel stations to have bad fuel. Up here there are lots of examples of bad fuel and given the insane price of fuel these days and the low profit margins for fuel stations survival comes first.

Also, the older cars will misfire and cut out badly on any fuel containing a mixture like E10. E10 is bloody first class rubbish fuels for the earlier cars.

Disconnect your fuel line to the carbys and then pump a clear clean glass full of fuel and then inspect it. Water in fuel is also a big problem.
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 1927
Registered: 4-2016
Posted on Thursday, 07 June, 2018 - 07:58 am:   Edit PostDelete PostView Post/Check IP

Jeff.

The symptoms are identical to my switchbox problem a year or so ago.
You should be able to find the pics I posted.
The contacts were so bad the car just stopped intermittently.

Then it would be ok for months.
Once the switchbox was rebuilt, all good.
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richard george yeaman
Grand Master
Username: richyrich

Post Number: 974
Registered: 4-2012
Posted on Thursday, 07 June, 2018 - 08:31 am:   Edit PostDelete PostView Post/Check IP

A few years ago my Shadow had similar symptons after a lot of head scratching and money spent on coils and distributor parts it turned out to be my ballast resister.

Richard.
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Jeff Cheng
Prolific User
Username: makeshift

Post Number: 107
Registered: 2-2016
Posted on Thursday, 07 June, 2018 - 11:34 am:   Edit PostDelete PostView Post/Check IP

Thanks everyone for your insights and suggestions.

Stovepipes:
I will give them a tug next time I run the car and check for vacuum leaks with starter spray and report back.

Fuel:
I only topped off the tank from 2/3 as fuel was cheap. I only ever use 98ron Premium fuel, and there was so other signs of bad fuel (no poor running before, or after the FTP).

Ballast resistor:
I thought this was a possibility as it's one of the part I didn't replace last year. I've read on here about corrosion causing issues. I always thought the ballast resistor would show itself as hard starting, which it has never experienced. Do ballast resistors heatsoak?

Switchbox:
This has also crossed my mind, but she has never faltered over rough surfaces, and there are no other tags/keys on the ring. As a test, I jjiggled the key vigorously while she was idling away, and couldn't replicate anything. Doesn't rule it out though.

I did doublecheck all the terminals on the coil/ballast/igniton module, with nothing overly loose or out of the ordinary.

I guess there's not much I can do for now but drive it around and see if it will happen again. I will keep you updated.

Jeff.
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Jeff McCarthy
Grand Master
Username: jefmac2003

Post Number: 515
Registered: 5-2007
Posted on Thursday, 07 June, 2018 - 12:00 pm:   Edit PostDelete PostView Post/Check IP

Good plan Jeff. With the stovepipe you can tell if it's the original if it has the ratty looking white (asbestos!) insulation covering it.

If so I would advise prophylactic replacement before it fails - it's 40 years old and should have been done decades ago.

Cheers

Jeff
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Alan Dibley
Prolific User
Username: alsdibley

Post Number: 149
Registered: 10-2009
Posted on Thursday, 07 June, 2018 - 05:32 pm:   Edit PostDelete PostView Post/Check IP

I replaced the hot bit of the stovepipe with Cunifer/Kunifer brake pipe, and covered it with adhesive glass-fibre tape. Not original, of course, but has worked OK for 10+ years.

Alan D.
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Jim Walters
Prolific User
Username: jim_walters

Post Number: 166
Registered: 1-2014
Posted on Thursday, 07 June, 2018 - 06:02 pm:   Edit PostDelete PostView Post/Check IP

Every Shadow owner should carry a spare ignition rotor in their car unless they have installed a red one from the Distributor Doctor.
http://www.distributordoctor.com/red-rotor-arms.html

And should read this:
http://www.distributordoctor.com/rotor_arms.html

Even if your rotor was new a year ago, it means nothing if it is one of the poor reproductions on the market. Your symptoms are in line with a defective rotor. I'm not saying that is the fault, but it is an easy thing to check and/or replace. I have seen lots of them fail in client's cars over the years, it has even happened to me in my own Shadow.
Also Jeff, if you get one of those spark plug testers as I mentioned previously you can quickly place it on either a spark plug or the coil high tension lead. If you place it between the coil HT lead and cap you can confirm if you have spark or not. If you have spark there that eliminates a whole bunch of possible culprits. Next, place it on a plug lead. No spark - shorted rotor. Spark - fuel issue. If you have spark at the plugs, before you go checking pumps and filters, remove the vent hoses from the carb float bowls. This will eliminate the weakener and anti run on solenoids as possible faults. With over 40 years of working on these cars you learn to diagnose and narrow down the cause of an FTP quickly.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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Patrick Lockyer.
Grand Master
Username: pat_lockyer

Post Number: 1889
Registered: 9-2004
Posted on Thursday, 07 June, 2018 - 06:39 pm:   Edit PostDelete PostView Post/Check IP

Tip, if your rotor arm packs up on route with no spare some insulating tape doubled up and fitted between the shaft and rotor gets you home!

Spark plug HT tester..... IMO just hold the lead and crank if you feel currant should be ok and good for the heart I am told!

For the test with a new plug, fit plug to the coil HT or plug HT and see if it sparks, one less tool to look for!
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Jeff McCarthy
Grand Master
Username: jefmac2003

Post Number: 516
Registered: 5-2007
Posted on Thursday, 07 June, 2018 - 06:59 pm:   Edit PostDelete PostView Post/Check IP

Jim,
Thanks for those links. I've just contacted them to get some sent down under. The info on the site is very useful - especially the stuff on condensers.
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Jeff Cheng
Prolific User
Username: makeshift

Post Number: 108
Registered: 2-2016
Posted on Thursday, 07 June, 2018 - 07:18 pm:   Edit PostDelete PostView Post/Check IP

As my FTP's were in the middle lane of a 3 lane main street in peak hour traffic, I didn't get much opportunity to do much troubleshooting there and then, my priority being to get it off the road safely. When it started back up (and didn't cut out), it drove all the way home fine, so no replication of fault to troubleshoot.

Jim;
I have indeed heard of the defective rotors doing the rounds. Are there usually tell-tale burn marks from the current arcing where it shouldn't? While mine is just a standard FS rotor, there are no scorch marks from current leakage, and the rotor tip is wearing as expected for the 1000miles on it.
I have a similar design spark plug tester, fantastic little gadget and much easier to use than sticking a screwdriver in the HT lead and holding it by hand close to a ground.

Jeff;
If you do hear back from the mob regarding the red rotors, I would be more than happy to chip in on a group buy to save shipping if they require a minimum order.

With rain forecast the next week or so, it looks like I might not be able to go out troubleshooting for a little bit.

Maybe I can convince the wife to pack a picnic and let the car choose our destination...
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Jim Walters
Prolific User
Username: jim_walters

Post Number: 167
Registered: 1-2014
Posted on Friday, 08 June, 2018 - 04:12 am:   Edit PostDelete PostView Post/Check IP

Jeff, yes the condensor info is a must read too. The Distributor Doctor has the price break at 25 rotors. One to 24 - £15.95, 25 up £7.50. (I have no affiliation etc.)
The rotors usually short through the material to the shaft underneath so will not show a carbon trail. When testing rotors I have seen the spark jump around the side to the shaft, in which case you may see some tracking.
Two good reasons to use a tester and not hold the lead by hand. One, you can easily do it without a second person cranking the engine while you hold the lead. Two, you avoid the risk of a nasty shock.
Also Jeff, a handy test gadget you can make up and drive around with is a small 12 volt light bulb or LED. Use either a small socket and wires for the 12 volt bulb or solder wires to the LED. Ground one wire (observe polarity with an LED) and attach the other to the coil negative terminal. Lay the bulb/LED up onto the cowl under a wiper arm and tape it to the windscreen so it is in plain view. Next time the engine quits, observe the light. If it is flashing when you crank and try to restart, then you know the ignition switch, start relay, ignition module, are OK. This test confirms that the module is triggering the coil to fire. If you are quick you can glance at the light just as the engine quits and see if it is still flashing as the engine stops turning over. Then if it is flashing you can go on with testing for spark at a plug to confirm operation of the coil and rotor. If that all works then you know you have to look at fueling issues.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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Jim Walters
Prolific User
Username: jim_walters

Post Number: 168
Registered: 1-2014
Posted on Friday, 08 June, 2018 - 04:19 am:   Edit PostDelete PostView Post/Check IP

Also, how to test for a faulty rotor. Remove coil lead from distributor cap. Remove cap and tie out of the way so the rotor cannot hit it. Using insulated pliers, hold the coil lead within 1/8th of an inch from the centre of the rotor where the carbon brush contacts it. Have someone crank over the engine for you. IF a spark jumps to the rotor, it is shorting out through the plastic to the distributor shaft underneath. You do NOT want to see a spark jump to the rotor.

SRH8505 SRC18015 SRE22493 NAC-05370
www.bristolmotors.com
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Jeff Cheng
Prolific User
Username: makeshift

Post Number: 109
Registered: 2-2016
Posted on Wednesday, 13 June, 2018 - 07:57 pm:   Edit PostDelete PostView Post/Check IP

The weather has been pretty average the last week or so, but I have been able to take the car out on two occasions, each to run a local 15 mile loop in suburban traffic. No hard starting or issues at all.

I gave the stovepipes a good shake at idle, and (while they are original) they were both pretty solid. Sprayed some starting fluid around for good measure and found no vacuum leaks

Jim,
While there was a spark between the coil lead and the center of the rotor when I performed your recommended test, there was also a correlating spark from the rotor tip to the distributor body, bright blue and jumping almost 3cm!!
Please correct me, but I believe this confirms that my rotor is NOT faulty...? Since spark travels the path of least resistance, jumping the much farther 3cm distance from the rotor tip to the distributor body (compared to through the plastic to the inner shaft) demonstrates that rotor plastic has sufficient resistance/insulation...? I.e. the spark will jump the 3cm to a nearby ground before going through the rotor itself

My car is running a rebuilt Opus electronic ignition module, so no condenser, right? I cannot find one and only have the RFI suppressor on the coil terminal.

Since I had to put an order through flying spares, I ordered a new ballast resistor since they're cheap enough. It's the only ignition component that was not replaced last year (Opus, coil, cap, rotor, plugs, leads).

Thanks for all your advice, I will keep updating this thread with any developments.

Jeff.
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Patrick Ryan
Grand Master
Username: patrick_r

Post Number: 1928
Registered: 4-2016
Posted on Wednesday, 13 June, 2018 - 08:15 pm:   Edit PostDelete PostView Post/Check IP

Good luck Jeff.

Iím following this with interest.
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 249
Registered: 7-2012
Posted on Wednesday, 13 June, 2018 - 08:46 pm:   Edit PostDelete PostView Post/Check IP

Depends on what emission system is fitted, but it is worth venting weakener system by just removing float chamber depression sampling cap. I just leave mine off all time and no issues. If the weakener system is not working correctly and too much depression on top of fuel in float chamber, this will in fact hold fuel back, giving symtoms described. Just another thing to consider!
Item is cap on float chamber, no 2 on illustration. Hope helps.
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Jeff Cheng
Prolific User
Username: makeshift

Post Number: 110
Registered: 2-2016
Posted on Wednesday, 13 June, 2018 - 09:05 pm:   Edit PostDelete PostView Post/Check IP

Thanks Gordon and Jim for the suggestion of the weakener system.

Although it's not very scientific making multiple changes at once trying to diagnose an issue, I have just ducked into the garage and disconnected the carb float bowl vent hoses to eliminate the weakener system on your suggestion.

Jeff - who is not averse to throwing parts and ideas at a car, as long as it ends up fixed.
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gordon le feuvre
Prolific User
Username: triumph

Post Number: 250
Registered: 7-2012
Posted on Wednesday, 13 June, 2018 - 10:28 pm:   Edit PostDelete PostView Post/Check IP

Jeff, just remove cap, as you do not want problems if float chamber happens to over fill.

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