Why won't my engine start?

So your treasure won't start? Worry not - it happens to all of us at some point.

Pour courself a cuppa, take a deep breath, and let's narrow the problem down to possible culprits...

MOWOG A series engine in a Jimny

Why won't my petrol engine start?

Ignition switched off

Flat battery

No or poor earth from battery to chassis

No or poor earth from chassis to engine

Poor electrical connections

Damaged spark plugs

Incorrect spark plug gaps

Damaged or dirty spark plug caps

Faulty HT (high tension) leads

Defective ignition coil

Defective condenser

Worn distributor rotor arm/cap

Broken contact-breaker spring

Incorrect distributor point gap

Oil/grease on distributor contacts

Burnt distributor points

No fuel (faulty fuel gauge?)

Incorrect idle adjustment

Sticking SU carburettor piston

Sticking carburettor float bowl valve

Blocked air filter

Dirt in petrol supply

Blocked fuel filter

Faulty fuel pump

Air-lock in fuel feed pipes

Fuel cap breather blocked

Why does my engine start then stall?

Insufficient fuel in the tank (this may seem obvious, but fuel gauges can tell fibs)

Fuel cap blockage

Blockage/constriction in fuel line

Air-lock in fuel line

Faulty fuel pump

Water in fuel

Water in carburettor

Incorect idle adjustment

Intermittent/poor electrical connection

Poor HT lead connection

Loose distributor clamp screw

Faulty ignition circuit

Why won't my starter turn the engine?

Flat or low battery

Poor earthing

Poor/faulty electrical connections

Faulty starter switch

Faulty starter solenoid

Faulty starter motor

Short circuit in starter system

Broken/damaged starter motor pinion

Broken teeth on engine flywheel

Engine seized

Gearbox seized

Flywheel gear pinion jammed


Why is my engine drinking fuel or oil?

Retro fuel pump.jpg

Has your engine developed a drink problem? It can happen to the nicest of vehicles. Try the It's My Classic step by step checklist to help rectify excessive fuel or oil consumption.

Excessive fuel consumption?

Corroded/leaking fuel tank

Cracked/leaky fuel line

Leaky fuel line connections

Incorrect idle adjustment

Faulty choke

Carburettor mixture too rich

Damaged carburettor float

Incorrect carburettor float level

Worn carburettor needle

Damaged fuel pump diaphragm

Incorrect ignition timing

Incorrect tyre pressure

Brakes binding

Blocked/dirty air filter

Excessive oil consumption?

Damaged oil pipe

Leaky connectors

Overfilled sump

Worn/broken gaskets

Worn bearings

Excessive crankshaft bearing clearance

Damaged crankshaft oil seals

Worn valves or valve guides

Worn cylinders

Worn pistons

Broken or sticking piston rings

Wrong piston ring clearances

Blocked engine breather


Why is my engine overheating?

Is your engine getting a bit hot under the pistons? Does a warm day send your thermostat rocketing?


Here's the It's My Classic checklist for trouble-shooting your overheating engine.

Overheating engine? is it...

Low coolant level

Water flow obstruction (incl. radiator)

Incorrect coolant additive ratio

Faulty thermostat

Incorrect thermostat for engine

Leaky water pipe

Leaky radiator

Leaky radiator cap

Leaking core plugs

Faulty gasket on water pump

Obstruction to air flow through radiator

Faulty electric fan (if fitted)

Closed radiator shutter (if fitted)

Incorrect ignition timing

Broken or slipping fan belt

Low oil

Wrong oil pressure relief valve setting

Incorrect carburettor jet

Carburettor mixture too weak/lean

Brakes binding

It's My Classic - the free online classic car and motorcycle magazine for people with a passion for heritage vehicles.