[Top] [All Lists]

Re: [Mgs] too rich or too lean?

To: "Aaron Whiteman" <>, "MG Mailing List"
Subject: Re: [Mgs] too rich or too lean?
From: "Paul Hunt" <>
Date: Mon, 26 Oct 2009 08:51:54 -0000
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 


----- 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.


Support Team.Net

<Prev in Thread] Current Thread [Next in Thread>