Check the timing when cranking, should show approximately correct timing on
1 and 4 and on 2 and 3 it will be 180 degrees out. But if it starts with
ether it probably isn't spark, unless it is weak sparking due to a bad
condenser. Remove the coil HT lead while cranking and see how far you can
get a spark to jump. Should be at least 1/4"
After cranking for a while take out each plug and check for fuel. They
should smell strongly but not be wet. Wet indicates rich or flooded, no
smell indicates no fuel getting through or very weak. If no fuel or very
weak check for a major vacuum leak around the inlet manifold, particularly
the Welch plug at the back end. The anti runon valve can also cause fuel
starvation and should only operate when the ignition switch is in the off
position and when the oil pressure switch is closed. The pressure switch
operates from very low pressure upwards i.e. when ever the engine is
running. Disconnecting either wire at the valve, or the wire at the
pressure switch, will eliminate the valve. Other problems in the emissions
and anti-runon plumbing could cause a similar effect, remove the overflow
pipe to the charcoal canister from the carb(s) to eliminate these.
As long as you have fuel, air and spark in approximately the right
quantities at approximately the right time it should start.
Good luck,
PaulH.
----- Original Message -----
From: "Christian, Wellner L. CIV COMNAVAIRSYSCOMPATUXENTRIVERMD AIR 4.1.1.4"
<wellner.christian@navy.mil>
To: "MG Digest (E-mail)" <mgs@autox.team.net>
Sent: Thursday, January 08, 2004 12:10 PM
Subject: 1974 MGB Died While Driving
> On Tuesday afternoon, after prolonged cruising at around 4200 RPM, car
started to break down when RPM dropped below approx 3000.
|