Troubleshooting an Engine that is Hard to Start

In much of the country, fall and winter cold weather can make cars hard to start. When temperatures dip and engines get cold, batteries can weaken, oil thickens and fuel evaporates less quickly when it’s needed most — at startup. 

But hard engine starts aren’t just a cold weather phenomenon. If your vehicle needs to crank for more than a few seconds to start, there are some common culprits, regardless of the temperature. Read on to learn the common causes of hard starting engines and how to address them.

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The primary reasons (and there are a couple exceptions) you might be having a hard time starting your engine can be lumped into a few basic categories: air intake, fuel delivery, and ignition or spark. These are the ingredients every internal combustion engine needs to run. 

Before we get into what to look for, we’re going to first assume that your battery is in good shape and your car is cranking normally. Car batteries tend to last about four or five years under normal use. If your car is cranking slower than usual, you are noticing dim headlights or other electrical issues, or your “check engine” light is on, get your battery tested. 

If your battery is good and your car is cranking, but not starting right away, look for these potential problems:

Clogged Air Filter

Your engine needs to be able to draw in clean air to start and perform well. If air is restricted by a dirty filter, it can lead to hard starts and sluggish performance, such as poor acceleration. Your air intake assembly — including the tube or “boot” connected to your intake — could also be at fault. Cracks or disconnections in the assembly can lead to poor sensor readings that can impact starting.

Restricted Fuel System

A failing fuel pump is a common factor in hard starting vehicles. Over time, a pump can wear out and not deliver the correct amount of fuel that an engine needs to run as it should. Clogged or dirty fuel filters, injectors, and lines can also restrict fuel delivery.

Ignition System Problems

The primary culprits here are fouled spark plugs. Spark plug electrodes wear down over time, increasing the voltage needed to jump the gap in the plug and ignite the fuel and air mixture in the cylinder. That leads to longer cranking times before an engine fires up. Keep in mind that other parts of the ignition system, such as plug wires or your distributor, can also cause spark problems.

Compression and Timing Issues

Working air, fuel and ignition systems mean little if your vehicle’s timing is off or if the engine has lost compression. Proper compression and timing are crucial for an engine to start and run properly.

Failing Starter

Your vehicle’s starter needs to crank rapidly to turn over your engine. If your battery is good, but the car is still not cranking quickly, it’s a sign that your starter is not working as it should.


Beyond the issues listed above, other more complex factors can contribute to hard starts, but you can address the most common causes yourself. 

Those included checking and changing your air filter as needed and inspecting your air intake assembly for damage. Change your spark plugs at manufacturer-recommended intervals and regularly check your plug wires to make sure they are properly connected and not burnt. Always use fresh gas, check and replace fuel filters as needed, and use a fuel treatment to maintain a clean fuel system.

SEA FOAM MOTOR TREATMENT is a fast, easy and low cost DIY fix for preventing or overcoming common causes of hard starting.

Sea Foam offers a couple of primary solutions to help keep your vehicle starting quickly year-round. Treating fuel with Sea Foam Motor Treatment at every fill-up is a sure way to keep your fuel passageways and injectors clean. Have an older vehicle? For cars and trucks with more than 75,000 miles, Sea Foam High Mileage can help keep them starting like new.