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Post by jeff on Jul 11, 2024 12:43:57 GMT
Hi everyone,
Getting my mk1 morris ready for Gaydon show. Put fresh E5 petrol in and went for a 20 mile run without problems. Stopped to get stuff from Tescos, restarted OK then, in slow traffic began stalling on tick over. Restarted about 10 times.
Got home, all OK. Restarted when cooled off a bit, then after a short time, conked out on tick over but restarted OK.
By keeping Choke out on fast idle it keeps running but a bit chuffy. I reset air filter to summer setting. The coil, fuel pump, and points and condenser were replaced last winter.
Feels like a fuel problem.
I put in a fuel filter with a new tank last summer. I would have thought if filter was choked it would stall even more on high demand. Seems very odd to run well then play up after a short stop.
Are our cars known for fuel evaporation?? All seems very odd and difficult to pin down.
Any ideas folks?? Thanks.
Jeff
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Post by dave1800 on Jul 12, 2024 10:29:40 GMT
Hi Jeff Not an easy one to diagnose. There are many reports on the MGB forums about difficulties starting after stopping for a short while but none that I've seen that match exactly your car's symptoms. In theory the 1800 should be even more prone to fuel evaporation as the manifold is close to the bulkhead. I agree it does sound more likely to be fuel related. It would be worth checking that the float chamber valve is not sticking open and closed as this could lead to flooding and stalling at idle and maybe also difficult hot starting. The float valves can become gummed up or trap debris. You can check the spark plugs to see if they are black and wet with fuel when it stalls.
As you say, the filter would be more likely to cause starvation at higher rpm.
David
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Post by Penguin45 on Jul 12, 2024 19:18:43 GMT
Low carb float causes some interesting problems.
C.
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Post by jeff on Jul 12, 2024 19:22:21 GMT
Thanks Dave. After loads of checks I resorted to replacing the condenser. All was fine until just going into the garage and trying it out.
It started OK but on revving up it stalled when falling back to idle, and had difficulty restarting. Sometimes it will, sometimes it won't.
I did check the float valve setting and operation today and it seemed ok. However, on checking the plugs, a light black sooty coating was evident which wiped off easily..
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Post by dave1800 on Jul 13, 2024 1:25:52 GMT
It looks as though there's nothing immediately obvious. The problem seems to have started after adding new fuel so that could be suspect or just coincidence.
You mentioned you changed the coil, fuel pump etc last year. Is the replacement fuel pump an original low pressure SU? The SU float valve is very sensitive to the fuel pressure, and anything over will cause flooding and stalling at idle.
It is now down to the usual checks, is there fuel still being delivered when it stalls, are there any air leaks at the manifold, PCV diaphragm or servo hoses. Is the SU piston dropping fully and freely and the damper topped up.
It may be worth swopping the coil for the original unless that had actually failed. I have had weird running problems in the past that turned out to be a failing coil even though it tested correctly.
The usual electrical suspects are loose spade connections, the distributor cap and its carbon brush, rotor arm and capacitor. The latter two are especially problematic.
As Chris mentioned the fuel level in the float chamber can cause odd problems. You can check this by removing the carburretor suction chamber and the fuel should be around 3/8" below the bridge.
Good luck!
David
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Post by jeff on Jul 21, 2024 14:56:10 GMT
Seems OK now. No problems to and from Gaydon after going through everything with a fine tooth comb. A Few years ago I added a used rev counter from an MGB. I was never happy with it as it sometimes bounced quite a lot, indicating a fault. Guess what? I disconnected it and now the car starts instantly, no intermittent stalling etc which just goes to show the garden path can lead us to the strangest of places.
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Post by Penguin45 on Jul 21, 2024 23:31:07 GMT
That's just weird! There's some sort of induction sensor in the gauge, other than that, I don't know much about them.
C.
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Post by jeff on Jul 22, 2024 0:14:22 GMT
Chris,
I have been assured that these old taco's (spark counters), wired into the coil feed and earth, suffer deteriorating electronic components as they age. The internals, soldered joints, capacitors, transistors etc become weak and can cause problems with the ignition circuit in the car.
There is a fix available where the internals are replaced with a modern integrated circuit, but externally look the same.
In my case, I don't think I'll bother. Just now it's running on top form so probably best to leave it.
Jeff
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Post by dave1800 on Jul 22, 2024 1:47:50 GMT
Someone said something like "90% of carburretor faults are actually down to Lucas", can't find the original quote. The earlier rev counters were wired in series with the ignition coil switched terminal and simply wound the wire around an iron core a few times to provide an inductive pulse. In theory nothing to go wrong with that part other than a dry joint,short or wire fraying. I said "in theory"  . The rev counter electronics, transistors etc should not cause the symptoms even if they have failed or are failing. May be worth a quick look, given the symptoms it may be an easy fix. David Seems OK now. No problems to and from Gaydon after going through everything with a fine tooth comb. A Few years ago I added a used rev counter from an MGB. I was never happy with it as it sometimes bounced quite a lot, indicating a fault. Guess what? I disconnected it and now the car starts instantly, no intermittent stalling etc which just goes to show the garden path can lead us to the strangest of places. |
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Post by andrewa on Jul 22, 2024 5:19:54 GMT
Glad you got it sorted - those intermittent faults can drive you round the bend - or not!
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Post by jeff on Jul 22, 2024 15:49:19 GMT
Cheers for the comments lads.
The type of Tacho I fitted was the later RVC type, as opposed to the earlier RVI type. RVC just uses a sensor wire connected in parallel, from the distributor side of the coil, in my case Negative as car polarity was swapped years ago. The earlier RVI type, as said, is wired in series.
The only other connections are the case earth and it's lamp.
At Gaydon show I had a good conversation with Nick Basford, my cars previous custodian. He his quite well versed in electronic matters and explained having multiple capacitors (condensers) in the circuit including the one in the distributor, can cause weird ignition faults if they start falling out with each other.
The tachometer, is a usefull instrument, letting you know just how much the engine is being flogged. At 3000 rpm my landcrab would be cruising along at about 50ish mph. If I hit 3000 rpm in my golf diesel, I'd soon get nicked for speeding, probably dangerous driving on the motorway.
When I drive the Landcrab ,it always feels as though it should have had a 5th gear. Just imagine a 7 speed DSG Semi auto box as is in the Golf diesel. Sheer luxury! But without a tachometer, I revert to what I was told when learning to drive in the 1960's
"Ah well now young Jeffrey, the good driver ALWAYS listens to his engine".
When driving
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Post by dave1800 on Jul 23, 2024 5:39:05 GMT
I always felt that the Crab should have had higher gearing. The very early Mk1 cars were even lower geared and I think their final drive ratio was retained in Australia. Back in 1964 50 mph was deemed a good speed, (not by me  ) other than on a motorway. What I found suprising was that my Crab and Saab 9000 returned similar fuel consumption on a run even though the latter gearing was considerably higher and they were not dissimilar in weight but the Saab was aerodynamic and benefitted from a sophisticated engine management system. It is good to hear you have sorted out the stalling. Intermittent faults can be very frustrating. Did you try reconnecting the tacho to be 100% certain it was the culprit? It does sound as though it had an internal fault and being the sensor type could well have leaked the 360 volts that develops across the coil primary when the points open and caused the stumbling. The symptoms are a bit weird but where electronics are involved there are no surprises! David |
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Post by jeff on Jul 23, 2024 17:18:23 GMT
Dave, I'm guessing here but no doubt because the MK1 had only 13inch wheels, the overall gearing is lower. My old MK2 felt much more relaxed on its 14inch wheels and no doubt had a final drive to match.
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Post by dave1800 on Jul 24, 2024 0:46:01 GMT
Hi Jeff The change from 13" to 14" wheels only raised the tyre circumference by 1.6% as the width was reduced to 165 from 175. Early Mk1 cars 16.39 mph per 1000 rpm Later Mk1 cars 17.69 mph per 1000 rpm Mk11/11 cars 18.20 mph per 1000 rpm There was also a lower ratio available for Mk11 cars (? used in Australia) and the automatics were slightly higher geared. Your Mk11 may have felt a bit more relaxed as there were other changes such as the use of slipflex metalastik in place of roller bearings that produced a more damped less bouncy ride and larger inlet valves with higher compression that shifted the torque characteristics up the rpm range. If you need to know which differential you have in your Mk1 you may need to reinstall the tacho! David |
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Post by jeff on Jul 24, 2024 11:59:56 GMT
Think I might get a new or refurbished tachometer. I've had three used ones and they either bounced like mad or caused ign problems. Upwards and onwards
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. The rev counter electronics, transistors etc should not cause the symptoms even if they have failed or are failing. 
) other than on a motorway. What I found suprising was that my Crab and Saab 9000 returned similar fuel consumption on a run even though the latter gearing was considerably higher and they were not dissimilar in weight but the Saab was aerodynamic and benefitted from a sophisticated engine management system.