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Fault Diagnosis 

Help - My Morris Won't Start!
The information below is provided in the order that it should be checked, starting with the 'first checks' tab

First Checks

Have you got petrol in the tank?

 

​​​​Open the bonnet - are there any obvious disconnected wires or hoses?​

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Could you have over choked and flooded the engine?

If this is the case, start the car with the choke in and your foot fully down on the accelerator. Once started, ease back on the accelerator until you get even running.​

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Does the ignition warning light come on?

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If the ignition light doesn't come on, check the following: Check the battery output, which should be above 12v at the battery Check and clean the battery connections Check and clean the earth to body cable  Check all the connections between the battery, solenoid and starter If your ignition warning light didn't come on, check the wiring to the ignition switch

Starter

The starter motor doesn't make any sound or just hums

If the starter makes no sound, there are 4 possible explanations:

  1. The starter motor is jammed

  2. The starter motor is faulty

  3. There is an issue with the  amount of electrical supply to the starter

  4. There is a fault in the electrical system supplying the starter

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Switch on the headlamps and ask someone to watch them whilst you try to start the engine.

  • Lights already dim - this is an issue with the electrical supply

  • Lights go dim when trying to start - this suggests a jammed starter motor or a faulty starter motor

  • Lights are bright with no change - issue with the electrical system

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Jammed Starter

  • To free a jammed starter motor, turn off the ignition and use a spanner on the square end on the starter, turning it either way to free the motor.

  • Alternatively, with the ignition switched off and the car on flat ground (not a hill) put the car in 4th gear and rock it backwards and forwards. You may feel a sudden release.

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Issue with electrical supply or system

Check the battery output, which should be above 12v at the battery

Check and clean the battery connections

Check and clean the earth to body cable 

Check all the connections between the battery, solenoid and starter

If your ignition warning light didn't come on, check the wiring to the ignition switch

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The Starter Motor is noisy

This is likely to be to do with a fault within the starter motor or a starter motor is worn.

Whilst there are a number of steps that can be taken to inspect and repair a starter motor, it is likely to be simpler to replace it. 

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The Starter Motor Turns the Engine Slowly

Check the electrical connections

Check the battery output

If both of these are satisfactory, then there will be an issue with the solenoid or starter motor itself.

One possibility is that there is dirt on the pinion assembly or a broken spring on the pinion assembly. It is possible to clean the pinion assembly but this requires removal of the starter motor.

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Ignition

Please be aware that the symptoms from issues with the ignition system and fuel system are very similar.

It is more likely that the issue will be with the ignition system, so it is suggested that this is checked first.

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  • Check all wires and leads within the ignition system

  • Remove the spark plugs in turn and clean, inspect and reinsert, in case of condensation. If any issues are suspected, consider replacing the sparkplugs

  • Check the points gap and with the ignition off, watch the points whilst the engine is turned to make sure that they open and close

  • Check and clean the rotor arm and replace if required

  • Change the condenser

  • Test the coil using a test lamp to check that there is electrical flow through the LT lead connection

  • Consider checking the ignition timing. It is unlikely that this would cause a running car to suddenly stop running, but may be the cause of very poor running

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Fuel System

Petrol Pump​

  • Does the petrol pump tick when you turn the ignition on?

    • If not, this may indicate an issue with the fuel pump or stuck points

      • Give a light tap to the body of the fuel pump and see if the fuel pumps starts to work.​

 

If no change:

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    • With the ignition switched off, remove the end of the fuel pipe that goes to the float chamber and put the open end in a safe container .

      • Turn on the ignition and see if a steady stream of fuel is seen.

      • If no fuel is seen, give a light tap to the body of the fuel pump and see if the fuel delivery improves.

        • If so, this indicates stuck points which have now been freed

    • If you get a steady flow of fuel, inspect the float lid and needle valve to make sure it isn't stuck

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Carburettor Cables

  • Inspect the movement of the choke and accelerator cables at the carburettor end to make sure they are moving freely and correctly

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Suction Chamber Piston

  • The suction chamber piston may be stuck.

    • Checking this requires undoing the damper rod and using the piston lifting pin to move the piston up and down.

    • The piston should drop quickly with an audible click.

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Air Filter

  • Inspect the air filter element which could be dirty and preventing air flow.

    • Clean or change it as required.

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Air Leaks

  • Check for air leaks around the area where the carburettor joins the manifold caused by loose joints or broken gaskets

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Fuel Contamination

  • Look inside the float chamber to check that the fuel is not contaminated

  • This could be water contamination

 

  • This could be sediment in the float bowl, causing fuel blockages 

    • If so, clean out using a rag or kitchen roll and also consider contamination of fuel within the rest of the fuel system

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Mechanical

It is unlikely that a mechanical issue would cause complete failure of the engine to start and run and is more likely to be seen in cases of rough running.

However, if all other steps have been carried out and no cause can be found, it is suggested that a mechanical cause is ruled out.

Most investigations used to look into a mechanical cause will need indepth mechanical work to be undertaken.

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Likely causes:

  • Stuck or broken valve or valve spring

    • This work would require removal of the rocker cover and checking the clearance of the valves as well as checking the movemt of valves whilst the engine is turned by hand.

    • The valves and springs would also need checking for breakages

  • Blown head gasket

    • It can be difficult to diagnose a blown head gasket based on symptoms alone, but you may see:

      • An increase in the mayonnaise on the oil filler cap (it is normal for a small amount of mayo to be seen in Morris Minors run on short journeys only and this shouldn't be mistaken for a blown head gasket)

      • Oily spark plug near where the head gasket has blown

      • Rough running

      • Difficulty starting

    • The common area for a head gasket to go is between cylinders 3 and 4

  • Loose Cylinder Head Nuts

    • Check for tightness and then if found, tighten the centre ones first and then outwards working diagonally across the head to 40ft/lb.

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