Skip to Content

Car Sat For Years Won’t Start (Don’t Do This)

I love starting a new project; the best part is assessing what condition she’s in and trying to get her running. When she fires up for the first time in years, it’s like a moment of magic, but there’s a long way to go before you can drive her.

out door classic jeep

So how do you start a car that has sat for years? Many components will need attention, but to get it running, you’ll only need to service these:

  • Fuelling system
  • Lubrication system
  • Ignition system

In this post, I’ll share the most likely problems with each of the systems and what you’ll need to do. But before we rush in, we need to be careful; it’s easy to cause major damage at this early stage. (more on this below)

Don’t Do This

Old Mercedes

It is very tempting to sling a battery into her and some gas and hope for the best. While you could get lucky, you can equally cause some very expensive and avoidable damage.

When old cars sit up for a few years, moisture in the cylinders can cause corrosion on the piston rings, and they stick to the cylinder walls. Cranking over the engine at this stage will force the pistons to break free and, in doing so, can very often crack the piston rings.

Now getting her running isn’t possible, but you won’t know that yet; that knowledge will only come after you’ve tried everything to get her running, and finally, you decide to do a compression test, and ……aha!

And yes, I’ve done it; I was young and eager, and I’ve learned my lesson.

Breaking the rings is easy to avoid, and if you watch any of the car resto programs on tv, you may already be familiar.

How To Start A Barn Find

Classic Mercedes Car

Step One:

Remove the spark plugs.

Step Two:

Mix up some oil and diesel fuel about half in half, using a funnel or a squeeze bottle, and add a good splash into each cylinder.

Step Three:

Allow the solution to do its work for at least twelve hours.

Step Four:

After the soak period and if the car is fitted with a manual transmission and it moves freely, place it in top gear. Now have a helper rock the car gently forward and back while you watch for flywheel movement.

Spinning the engine over now will cause the oil/diesel mix to spray from the plug holes, so wear eye protectors.

If your car is fitted with auto transmission, you’ll need to use a breaker bar and socket. Turn the crank pulley (harmonic damper) gently until you see movement; the force applied should be progressive, not a sudden application of max force.

Free movement of the crankshaft is a good thing, and while it doesn’t guarantee the rings won’t be damaged, it does minimize it.

Recommissioning The Fuelling System

Old fuel is the main issue you’ll find with old cars that sit up for years. The gas in the tank will have evaporated, leaving a concoction of chemicals and moisture.

There are two main types of fuel systems – Carburettor and Electronic Fuel Injected (EFI). It just depends on how old your car is; most cars built in the last twenty years will be fuel injected, so I’ll start explaining the issues you may have with EFI first.

Components Of Fuel Injected System

EFI system
  • Gas tank
  • Fuel pump
  • Fuel filter
  • Fuel line
  • Fuel rail
  • Fuel regulator
  • Fuel injectors

Gas tank

Most EFI systems use a plastic gas tank, which is a real plus, which means you don’t have any corrosion issues.

However, you may still need to remove the tank from the car to thoroughly clean out the old gas and moisture. Any crap left in here will dog you forever.

Gas tank sending units (fuel gauge units) live inside the tank and suffer from corrosion. Although it won’t stop the car from starting, having no fuel gauge is a real pain.


The fuel pump may be fitted inside the gas tank or externally. The plastic and rubber components of fuel pumps are often attacked by old gas and moisture. So expect that you may need to replace the fuel pump.

Fuel pump

With the key in the “On” position, you should be able to hear the buzz of the gas pump; no noise suggests it may be dead.

Fuel filter

The filter will obviously need to be changed; old gas and moisture will block it.

Fuel line

The fuel line will likely be made up of a combination of metal, plastic, and rubber. The rubber fuel lines are the most likely to give trouble; check for cracking, especially around connections.

Fuel rail

Fuel rail stores the pressurized fuel ready for delivery to the injectors. Rails don’t cause any real problems.

Fuel regulator

Fuel regulator

The regulator, as it suggests, maintains a window of fuel pressure in the fuel rail; any loss of rail pressure will cause a no-start. Regulators are fitted with rubber and metal springs and are a common fuel system component to fail, especially the vacuum hose.

Fuel injectors

Most injectors are electro-mechanical and common failures here will include mouse-eaten wiring, corroded wiring connectors, and the oddly failed injector.

Components Of A Carburetor Fuel System

Racing engine

Now let’s take a look at the older carburetor-type fuelling system and see what common issues you might encounter.

The main components of a carburetor fuelling system include:

  • Gas tank
  • Fuel pump
  • Fuel filter
  • Fuel line
  • Carburetor

Gas tank

Metal tanks are common on older cars with carburetors. The main issue here is rust; the old gas and moisture will cause corrosion.

Loose rust in the bottom of the tank will block the gas filter and cause lots of drive-ability issues. The tank will need to be removed, cleaned, and sealed with a special gas tank sealer.

The fuel gauge unit lives inside the gas tank, and it, too, suffers from corrosion. Now’s the time to take care of it; corrosion on the electrical contacts will cause intermittent gas tank readings.

Fuel pump

The fuel pump on a carburetor system is nearly always a mechanical type fitted to the cylinder head and driven from the camshaft. These guys are pretty durable and easy to test.

Fuel filter

The filter will obviously need to be changed; old gas and moisture will block it.

Fuel line

The fuel line will likely be made up of a combination of metal, plastic, and rubber. The rubber fuel lines are the most likely to give trouble; check for cracking, especially around connections.


This is where most of your gremlins will live; the carburetor will likely need to be removed and cleaned.

SU carburettor

You can do a pretty good job with carb cleaner, but if you’re going to the trouble of removing it, consider using an ultrasonic cleaner. You can buy a handy DIY version that is perfect for the job.

The main issues with the carburetor include blocked-up fuel jets and, stuck fuel floats, worn gaskets causing fuel, and vacuum leaks.

Choke systems often give issues; early carburetors had a simple manual knob that controlled the choke flap. These types give the least amount of issues.

Later models had auto choke controlled by a thermostat; as thermostats get older, they get lazy and don’t work. After reinstalling the carburetor, it will likely need to be tuned.

By tuned, I mean adjusting the fuel-air mixture so that the engine is getting the optimum amount of gas; the idle screw will then need to be adjusted.

Recommissioning The Lube System

Jaguar oil cap

This is a pretty simple job; old oil will store contaminants, and that can damage your engine. Before starting the engine, change the oil and filter.

You’ll need to change the oil and filter again after a few hours of running; this helps clean the contaminants and moisture from the engine.

Ideally, you want oil pressure built up before starting an engine; easy enough to do when bench testing is a lot harder when it’s in the car. So when the car starts are sure not to rev the engine until oil pressure builds; this prevents damaging oil-starved components.

Recommissioning The Ignition System

Ignition system

The ignition system on old cars will differ depending on how old it is. Early models have more components to clean and adjust. Later models moved to electronic systems that are more durable and dependable.

The first purchase will likely be a new battery and check those battery cables and terminals for corrosion. The parts shop will size the battery for your model car; it’s important to get that right.

An Ignition system components include:

  • Plugs
  • Plug wires
  • Distributor
  • Points (Early models)
  • Coil & Electronic coils
  • Coil packs (Later models) & Coil over plugs (Latest models)


Old plugs will be corroded, electrode gap will be off; sure, you could adjust, but replacing is the way to go. Badly gaped plugs can cause more expensive components to fail.

Plug wires

Mouse-eaten wires are the most common issue. If the plug wires can’t carry the voltage, the engine won’t run right.


The distributor’s cap and rotor both degrade over time. Cracked caps and rotors are common and will prevent the engine from starting.

Distributor cap


Points are fitted to early models and are housed inside the distributor. It is integral to getting the spark to the plugs, and without a doubt, if you have them, they’ll need to be cleaned or better replaced.

Coil & electronic coil

The coil is like an amplifying machine; it takes a small voltage and turns it into a big voltage. Coil failure is common and, ironically, usually fails after the engine has been started. Moisture trapped for years within the unit shorts out, causing failure.

Coil packs & Coil over plugs


These types of coils are still in use today; they are reliable but do fail. If your car has these types of coils, then your car is controlled by a computer, which means your car can be diagnosed using a code reader.

Other Recommissioning Work

Timing belt

While the type of work described above is enough to get the car running, it’s not yet safe to drive or let run for long periods. Other systems that will need attention include:

  • Timing belt
  • Coolant system
  • Brakes
  • Transmission
  • Tires

Timing belt

Not all cars will have a timing belt; some will have a chain. The timing belt is crucial to the safe operation of the engine; it keeps the top and bottom components of the engine in time. When they fail, and they do without warning, components collide, and the engine is badly damaged.

Coolant system

Replacing coolant and thermostat. Hoses may suffer from dry rot and failed clamps. The water pump is crucial to the system and will need to be changed.


Brake systems don’t age well, especially when sitting idle. Brake fluid attracts moisture even with the fluid reservoir cap fitted securely. The moisture now inside the brake system starts to corrode the calipers and cause problems. Common issues include seized brakes, binding brakes, and noisy brakes.

Brake parts


Changing the oil and filter before driving, as moisture in the tranny can cause other expensive problems.


Old tires just won’t be safe, and although they might look OK. The tires will be out of date, and if they have been sitting on the ground will have flat spots, which will feel horrible on the road.

Related Questions

What happens when you don’t drive a car for a long time? The gas goes stale and blocks up the fuelling system. Rubber engine components suffer from dry-rot. The coolant system components suffer from corrosion. The brakes system seizes. The electrical system suffers from corrosion and rodent damage. Interior components suffer from dampness and rot.

About the Author

John Cunningham is a Red Seal Qualified automotive technician with over twenty-five years of experience in the field. When he’s not writing about car repair, you’ll find him in his happy place – restoring classic cars.