You can accurately test the fuel pump, on your 1.6L Nissan Sentra, to see if it has failed and thus keeping your car from starting or just not sending enough fuel to the engine to keep it running optimally.
In this tutorial I'll show you how and where to connect your fuel pressure test gauge and what fuel pressure specification you should see. I'm also gonna' explain a simple and easy way to confirm a ‘lack of fuel’ condition by using starting fluid.
Contents of this tutorial at a quick glance:
- Symptoms of a Bad Fuel Pump.
- TEST 1: Using Starting Fluid To Confirm Lack of Fuel.
- TEST 2: Checking Fuel Pressure With a Fuel Pressure Gauge.
- Where to Buy a Fuel Pressure Test Gauge.
- Location of Fuel Filter Output Hose.
- Where to Buy the Fuel Pump and Save.
Puedes encontrar este tutorial en Español aquí: Cómo Verificar la Bomba de Combustible (1.6L Nissan Sentra) (en: autotecnico-online.com).
NOTE: The following tutorial may be of help in troubleshooting a ‘cranks but does not start’ condition: How to Troubleshoot a No Start (1.6L Nissan)
Fuel pump failures usually fall into one of two categories. In the most common type of failure, the fuel pump just stops working completely and the engine doesn't start at all. In the second type of failure, the fuel pump works just enough to start and keep the engine running, but the engine runs rough.
When a fuel pump completely fails, you'll see that:
- The engine turns over but will not start.
- All 4 cylinders are being fed spark (as checked by a spark tester).
- Your Nissan Sentra's fuel injection computer is activating all 4 fuel injectors (as checked with a Noid light).
- Fuel pressure PSI is 0 PSI when checked with a fuel pressure test gauge.
- Engine starts, although momentarily, if you spray starting fluid into the throttle body and then crank the engine.
When the fuel pump is starting to fail and under-performing, you'll probably see one or more of the following symptoms:
- Lean air/fuel mixture trouble codes.
- Rough idle.
- Engine starts after extended cranking.
- Lack of power when accelerating the vehicle down the road.
- Back-fires thru' the intake manifold when accelerating your pickup or van down the road.
Both of these conditions can be tested with a fuel pressure gauge. Alright, with this info under our belts, let's get testing.
If your Nissan Sentra doesn't start, the first test I'm gonna' suggest to you is the starting fluid test. Using starting fluid to find out if the fuel pump has stopped working is fast and easy (although it's not the most accurate way to diagnose a bad fuel pump).
But before you start this test, you first have to make sure that all 4 spark plug wires are delivering spark to their respective spark plugs. This means you need to do a spark test, with a spark tester, first.
IMPORTANT: This is a very fast and easy test but you do have to take one very important safety precaution and this is to reconnect the air intake duct after spraying starting fluid down the throttle bore (although you don't have to fasten it). This will prevent any backfire, that might occur, from scaring the heck out of you when cranking the engine.
This is what you have to do:
Remove the intake air duct from the throttle body. You don't have to completely remove it, since you'll have to reconnect it in one of the next steps.
Open the throttle plate and spray starting fluid down the bore.
As a safety precaution reconnect the air duct after you have sprayed a good squirt of starting fluid (but you don't have to tighten the air duct's hose clamp).
Crank the engine once the air duct is back on and you're clear of the engine compartment.
The engine will start momentarily and after a few seconds will die if the fuel pump is not working.
If the fuel pump is working, and thus sending fuel to the fuel injectors, then the engine won't start at all.
OK, let's find out what your results mean:
CASE 1: If the engine started and ran for a few seconds: This test result tells you that the no start problem is due to a lack of fuel.
Your next step is to check to see what the fuel pressure is with a fuel pressure test gauge. Go to: TEST 2: Checking Fuel Pressure With a Fuel Pressure Gauge.
CASE 2: The engine did not start, not even momentarily: This usually means that a lack of fuel IS NOT the reason your car is not starting.
Now, remember what I said about this test not being very accurate? Well, I suggest you do one more test and this is to check the fuel pressure with a fuel pressure test gauge. Go to: TEST 2: Checking Fuel Pressure With a Fuel Pressure Gauge.