Defect Location

    
     
 
SYMPTOM POSSIBLE CAUSE REMEDY
A—ENGINE FAILS TO FIRE WHEN COLD

1. Inadequate or no fuel supply

 

 1. Slacken filter plug on A.E.D. Crank engine, fuel should leak from
to A.E.D. plug.
If no fuel, check system leading to A.E.D. If fuel is present,
tighten plug. Then carry out check 2 under symptom A.
2. Inadequate or no fuel supply from A.E.D. to inlet manifold 2. Crank engine for several seconds. Remove pipe at inlet manifold.
If fuel is present, it indicates that the A.E.D. is satisfactory
and the cause for failure to start must be traced to some other
source. If no fuel is present this indicates a faulty A.E.D.
Proceed as follows:
(i) Check that main valve is open by inserting probe down centre hole—press down fully, probe should return approximately .030 in. (0,7S mm) when released.
NOTE: This check is not applicable when temperature is above 350C.
(ii) Remove float chamber lid, check that needle valve and float are free to move.
If there is no fuel in float chamber check that fuel filter is clean and that ample fuel is being delivered to the unit. See Operation N/Q 21A.
B—ENGINE FIRES BUT FAILS TO KEEP RUNNING WHEN COLD

1. Sticking or faulty needle valve or float

 

 

 

 1. Check the following:
i) Remove vent pipe from float chamber and check that fuel
is not discharged when cranking engine.
(ii) If fuel is discharged check operation of needle valve and float
as detailed under ‘A’ item 2 (ii).
2. Faulty air flap valve 2. Remove air inlet elbow on A.E.D. and check that flap valve is
free to move, and return under spring load. If jammed dismantle
unit and rectify.
3. Inadequate fuel supply 3. Check for lack of fuel as detailed under ‘A’ Item land ‘A’ Item 2 (ii).
4. Faulty jet needle diaphragm

4. Remove cap for needle diaphragm, then withdraw diaphragm and
check for damage. Replace faulty parts. Reassemble as detailed
under Operation NIQ 20A.

If diaphragm is satisfactory a complete overhaul of the unit is
indicated.

C—ENGINE FAILS TO START WHEN HOT OR PART WARM OR FIRES AND FAILS TO KEEP RUNNING

 

 1. Incorrect starting procedure 1. Crank engine and open throttle slightly, if unit is badly over-
choked open throttle fully do not over-rev. If engine starts but
fails to keep running carry out check 4’ below.
2. Leaks from pipe layout 2. Ensure’ that all pipes are correctly fitted, particularly the pipe
between the hot air pick-up and the A.E.D. Rectify as necessary
ensuring air tight joints.
NOTE: Air leaks at the hot air entry will result in excessive fuel
consumption and the possibility of stalling at certain
engine temperatures.
3. Before carrying Out further checks ensure that the A.E.D.is not the cause of failure tostart 3. Remove pipe from A.E,D. to inlet manifold. Blank off aperture
in manifold. If engine starts this indicates A.E.D. is at fault, and
further checks must be made. However, if engine is flooded it may
be necessary to crank for several seconds, with slightly open
throttle before the engine will fire.
4. Sticking or faulty needle valve or float 4. Check the following:
(I) Remove vent pipe from float chamber and check that fuel is
not discharged when cranking engine.
(ii) If fuel is discharged check operation of needle valve and float. Remove float chamber lid, check that needle valve and float are free to move.
if there is no fuel in float chamber check that fuel filter is clean and that ample fuel is being delivered to the unit. See Operation NIQ 2lA.
5. Main valve faulty. This fault and the checking procedure applies only when engine really hot. 5. Check that main valve is completely closed by inserting probe
down centre hole, press down fully, probe should not return which
is indicates that valve is fully seated. If probe returns under spring
pressure dismantle unit and rectity.
6. Incorrect, needle movement 6. Check movement of jet needle by inserting probe down hollow
grub screw, push down fully, if engine is at its normal working
temperature probe should not return, if partly warm, probe
should return approximately .015 in. (0,40 mm).
7. Faulty needle diaphragm 7. Carry out checks as detailed under ‘B’ Item 4.