Check List Carburettor carbutetor  Series    4A1                      Pierburg 4A1


Quick checks with assembled carburettor    4A1          GB
1. Remove air filter. 7. Check function of switch ventilation for float chamber. 13. Check bimetal spring and heater flaps in exhaust manifold for intake manifold heating for smooth operation.
2. Check intake air preheater (Vacuum unit leaks, function of thermo-valve and/or expansion element). Check carburettor attachment bolts for torque (10Nm), 8. Check thermovalve for TN starter air correction (Use thermopistol: cold closed, warm open)  (BMW/OPEL). 14.Check intake manifold area for leakage and cracks in hotspot area.
3. For BMW7OPEL visual inspection of thermal positioning motor (cold retracted, warm extended). 9.Check for air leaks in pulldown system, 2nd Stage vacuum unit, speed control and insulating gasket. 15.Check position of throttle lever reative to set screw at specified idle setting (no contact: possibly throttle valve worm).
4. Check O-ring between carburettor and air cleaner for distortion. 10, Check carburettor for visible distortion. Check air plates for smooth operation. 16.Close window for TN starter air with finger (idle speed must not drop markedly).
5. Check transmission lever of thermal actuator for smooth operation (BMW/OPEL). 11. Check idle setting according to manufacture specification and adjust, if necessary. Observer CO, increase rpm by throttle valve acturator. 17. Check uniform engagement of both main systems (above 2500/min possibly level too low;  seat of float needle valve displaced).
6. Check both cut-off valves. 12. Check function of pulldown unit.  
Maintenance Carburettor  4A1  BMW / Mercedes-Benz / Opel / Rolls Royce
Complaint: Possible Reason: Remedy:
Cold engine does not start. Choke plate does not close, throttle valve actuator does not position throttle valve. Smoothen and adjust choke plate. Install thermal timing valve 7.20242.00.   replace throttle valve actuator (1). For part no, refer to catalogue or data sheet.
Engine runs roughly after starting or stops. Defective thermal actuator or TN starter. Chocke lever missing. Replace thermal actuator (2) (BMW/OPEL).   Replace chocke lever (12).    For part no, refer to catalogue or data sheet.
Engine stops after starting. Pulldown diaphragm defective. Replace pulldown diaphragm (5) (BMW/Mercedes - Benz/Opel).  Adjust pulldown. Replace thermovalve (4).    For part no, refer to catalogue or data sheet.
rpm decreases unitil engine stops. Seat of float needle valve loose, fuel level too low. Install float needle valve seat (6) with oversize 1 or 2 4.07182.02 refer to Ti114 / Ti115.1
Rough engine running, low power (BMW 320/520). Worn cam on distributor intermediate shaft, mechanical fuel output low. Refer to Ti171, install electric fuel pump (7), if necessary. 7.21440.53
Poor engine starting in hot condition, low power output (BMW 320/520). Defective switch ventilation, switch ventilation not installed (Opel). Install electro-magnetic switch valve 7.20641.00 (Ti82.1).Install switch valve.   ( 8.2)
Poor transition to 2nd stage. Incorrect opening commencement of 2nd stage, plastic cam (9) for 2nd stage worn. adjust or replace air plate spring, spring set 4.07284.10 (Ti95) Install rocker (10) arm kit 4.07291.00     Replace choke flap repair kit (9) 4.07301.01
Idle speed remains high. Worn throttle valves. TN starter defective. Replace throttle valves (11) , refer to Ti125/Ti133  (BMW/320/520,525,630,728,730, Opel,Mercedes- Benz). Replace TN starter (12) .  For part no, refer to catalogue or data sheet.
Idle CO not adjustable (Too lean). Carburettor distorted (air leakage), crack in hot spot of intake manifold. Replace carburettor . Replace intake manifold. Replace heater plate shafts in exhaust manifold.
Low power output. Displaced fuel filter in carburettor. Choke plate closes during driving. Choke cover defective or not heated. Install new fuel filter (14) .  Check and replace choke cover (15).



Repair Kits Carburettor  4A1  BMW /  Mercedes-Benz  / Opel
Float kit


all 4A1 carburettors Float valve seat repair  kit 4.07182.02

( 6)

all 4A1 carburettors  Ti115
Float valve I  = 3.31440.01
                II = 3.31440.02
Return spring kit


all 4A1 carburettors Coke flap repair kit  4.07301.01

( 9)

all 4A1 carburettors
Choke lever kit 4.07243.08   BMW 4.07243.09   Opel   Needle jet 4.07271.20   BMW 4.07271.21   Opel  4.07271.22 Merced.2.79 4.07271.01 Merced.3.79
Thermal supplementary starter

( 12)

407265.00  Mercedes 280 4.07265.01 Mercedes 250 4.07265,02 Mercedes 250 4.07265.04   Opel   4.07265.06   BMW M60 4.07265.07   BMW M68 fuel filter 5.19203.01
Rocker arm kit   4.07291.00

( 10)

all 4A1 carburettors fuel filter

( 14)

manual vacuum pump 4.07370.02         pulldown-diaphragm   (Repair Kit)

( 5)

all carburettors throttle bodies

( 11)

Ti125 / Ti126

( 4)

BMW + Opel thermal timing valve 

 ( 1 )

all 4A1 Carbutettors
thermal actuator 

( 2)

 BMW + Opel electro-magnetic switch valve  Ti95      7.20641.00  = DB

( 8.2) BMW,+ OP = 7.20644.00

all 4A1 Carburettors
electric fuel pump

( 7)

7.21440.53   Ti171 choke cover 12V.

( 15)

all 4A1 Carburettors
Isulating gasket 3.50001.08  BMW M68 


3.50001.09 BMW M60


3.50001.10 Merced.M110

3.50001.14 Merced.M123


3.50001.15 Merced.M123


Datenblatt 4A1   BMW          
Datenblatt 4A1    DB          
Datenblatt 4A1  OPEL