No-Start 2: Checking For Fuel
A bad fuel pump will cause your 1.8L Nissan Sentra to crank but not start as the fuel pump is responsible for delivering fuel to the injectors.
Checking that the fuel pump is delivering fuel to the fuel injectors is not that difficult on your 1.8L Nissan Sentra.
What make it easy is that the pressure gauge can be connected between the rubber fuel pressure hose and the fuel injector rail using a suitable adapter (see photo 2 of 2 in the image viewer above).
The absolute best way to test the fuel pump is with a fuel pressure gauge, other methods are not as accurate.
However, the other method I have used to test for a lack of fuel is to spray starting fluid into the throttle body and then have a helper crank the engine.
If the engine starts with the starting fluid, I now know I need to take a closer look at the fuel pump to see if it's fried or not.
When testing the fuel pump with a fuel pressure gauge, you'll usually see one of two results:
CASE 1: Fuel pressure is within specification. This result not only tells you that the fuel pump is good, but also that the following components that power the fuel pump are good:
- The fuel pump fuse.
- The fuel pump relay (which is known as the Main Relay).
You don't have to spend time testing or money replacing them.
CASE 2: Fuel pressure is not present. This usually means that the pump has failed, but not always. I would recommend testing/checking the following before condemning the fuel pump:
- After verifying that there is no fuel pressure, verify that the fuel pump is getting power by checking the circuit that supplies it with 12 volts with a multimeter.
- This voltage must be checked while a helper cranks the engine. If 12 Volts are present, you have confirmed that the fuel pump fuse and the fuel pump relay are working properly.
- Confirming power to the fuel pump (with a multimeter) also confirms that the fuel pump has failed and needs to be replaced.
- If there is no voltage when your helper cranks the engine, the cause of the lack of fuel is either a blown fuse or the fuel pump relay (known as the Main Relay).
No-Start 3: Checking Engine Mechanical Condition
One of the most overlooked areas when testing a hard-to-diagnose engine no-start problem is the mechanical condition of your 1.8L Nissan Sentra's engine.
Checking the mechanical condition of the engine means an engine compression test and possibly a check for a blown head gasket (among other things).
- When conducting an engine compression test, look for an average compression reading of NO LESS THAN 120 PSI across all or most engine cylinders.
- If you have one or just two readings that are below 90 PSI, your Nissan Sentra will still start and run, albeit with a misfire.
- The following tutorial will help you do a compression test:
Engine No-Start Troubleshooting Summary
So in summary, the main cause of the cranks but does not start problem of your 1.8L Nissan Sentra is a lack of any of the following:
- Spark.
- Fuel.
- Air (from a lack of cylinder compression).
Fortunately, all of the above can be tested with simple tools. Which brings me to the next topic of conversation: checking the basics requires tools. There's just no way around it.
One of the analogies I always like to repeat, about doing a job without the right tools, is like trying to eat a bowl of soup with a fork.
So not only do you need to know what to test, you also need tools to do those tests. You don't need to spend an arm and a leg as you can buy many diagnostic tools tailored to fit the serious do-it-yourselfer's wallet.
Here are some of the basic tools you'll need:
- A fuel pressure gauge.
- A spark tester.
- A compression gauge.
- A multimeter.
Most of these tools can be purchased or rented free of charge from your local auto parts store (mainly AutoZone and O'Reilly Auto Parts -subject to a cash deposit which is returned when the tool is returned). If you want to save some money, you can also buy them online.
More 1.8L Nissan Sentra Tutorials
For a full list of tutorials, go to:
Below is a selection of articles that you can find in this article directory:
- How To Test The Starter Motor (2000-2002 1.8L Nissan Sentra).
- How To Test Engine Compression (2000-2006 1.8L Sentra).
- How To Test For A Blown Head Gasket (2000-2006 1.8L Sentra).
- How To Test Engine Compression (2000-2006 1.8L Sentra).
- How To Test The 2000-2002 Nissan Sentra 1.8L MAF Sensor (at: easyautodiagnostics.com).
If this info saved the day, buy me a beer!
