[Mgs] too rich or too lean?

Hans Duinhoven h.duinhoven at planet.nl
Mon Oct 26 11:52:22 MST 2009


Condensor getting faulty?

Cheers,

Hans
----- Original Message ----- 
From: "Paul Hunt" <paul.hunt1 at blueyonder.co.uk>
To: "Aaron Whiteman" <awhitema at panix.com>; "MG Mailing List" 
<mgs at autox.team.net>
Sent: Monday, October 26, 2009 9:51 AM
Subject: Re: [Mgs] too rich or too lean?


> Could be almost anything, especially since you have recently worked on 
> ignition and carbs.  What does the tach do for a start?  If that is 
> flicking all over the place then it is an ignition LT problem.  If it is 
> relatively steady then HT or fuel.  As it happens when cruising you may be 
> able to reproduce it with your head under the bonnet, if so clip a timing 
> light onto the coil and plug leads and watch the flashes.  Erratic 
> flashing on the coil lead indicates coil or possibly condenser problems. 
> Steady on the coil lead but irregular on the plug leads (remember the coil 
> lead flashes four times faster than any one plug lead) indicates that the 
> rotor or cap are breaking down, although that would be more likely under 
> acceleration than cruising. While on No.1 lead point it at the timing 
> marks to check that it is about right, and not jumping around.  If all 
> that is OK then it looks like carbs. Unlikely to be fuel starvation as 
> that would be worse under acceleration. Could be the aforementioned vacuum 
> leak, test with propane or carb cleaner, or possibly float valves, a 
> slight leak causing mixture problems under light fuel demand but not under 
> heavier demand.  If you have an SU pump turn on the ignition but don't 
> start the engine, and listen to the clicks.  Once the float chambers have 
> been filled the pump shouldn't click more than once every 30 secs.  More 
> than this indicates a leaking float valve or possibly a leaking one-way 
> valve in the pump inlet, although this latter is more likely to cause 
> problems under high fuel demand than low.  Remove the float chamber vent 
> pipes to see if one or other carbs does eventually start to overflow, this 
> can take several minutes, so disconnect the coil to prevent it 
> overheating.
>
> PaulH.
>
> ----- Original Message ----- 
>> ...  The spitting issue was much worse coming home.  Essentially,
>> after a half-mile of steady speed cruising, she would start this pop-
>> pop-pop shutter.  If I were climbing a hill, or accelerating
>> moderately, no problems.  I've recently set the timing and set the
>> carbs.


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