You can accurately test the condition of your fuel pump using a fuel pressure gauge. In this tutorial I'll explain the 2 most common methods of checking the fuel pump.
I'll also show you where you can buy a fuel pressure gauge that has the adapter to test your Honda Civic.
Alright, let's get started and find out if the fuel pump has failed and causing a ‘cranks but does not start’ condition.
Contents of this tutorial:
- Symptoms Of A Bad Fuel Pump.
- Where To Buy A Fuel Pressure Test Gauge.
- TEST 1: Checking Fuel Pressure With A Fuel Pressure Gauge.
- TEST 2: Using Starting Fluid To Confirm Lack Of Fuel.
- Location Of The Fuel Filter's Banjo Bolt.
- Where To Buy The Fuel Pump And Save.
- More 1.5L Honda Civic Diagnostic Tutorials.
You can find this tutorial in Spanish here: Cómo Verificar La Bomba de Combustible (1.5L Honda Civic) (at: autotecnico-online.com).
FUEL PUMP WIRING DIAGRAM: The following fuel pump circuit wiring diagram may come in handy: Fuel Pump Circuit Wiring Diagram (1992-1995 1.5L Honda Civic).
Symptoms Of A Bad Fuel Pump
Fuel pump failures usually fall in one of two categories. The most common is a complete failure of the fuel pump that prevents your 1.5L Honda Civic from starting.
The other is a fuel pump suffering a ‘slow death’ that isn't able to send the correct volume of fuel to the fuel injectors (in this case the car starts but runs badly).
Obviously, when the fuel pump completely fails your 1.5L Honda Civic isn't gonna' start. In this type of scenario, you'll see that:
- The engine turns over but will not start.
- The ignition coil pack is creating and distributing spark to all 6 cylinders.
- The PCM will still pulse (activate) all 6 fuel injectors.
But when the fuel pump sends a lower than normal volume of fuel, your will start and run but with engine performance problems. You'll probably see one or more of the following symptoms:
- 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.
Where To Buy A Fuel Pressure Test Gauge
You can buy a fuel pressure test gauge just about anywhere and is one of the most important tools any serious DIY'er should have in his/her tool box.
The following fuel pressure test gauge kits are pretty good deals and include the banjo-bolt test adapter:
All of the fuel pump pressure test kits above have the fitting that will connect to your Honda Civic's fuel system.
TEST 1: Checking Fuel Pressure With A Fuel Pressure Gauge
It used to be that to test the fuel pressure on any Honda, you had to buy a very expensive professional fuel pressure test gauge kit. One that usually had all of the adapters for all domestic and import makes and models and that usually cost more than US$300.00!
Within the past few years, as the DIY market has exploded, fuel pressure gauges have come down in price a lot and you don't need to buy an expensive fuel pressure gauge test kit.
So, in this test section, we'll use a fuel pressure test gauge to check the fuel pump's output pressure. The fuel pressure specification, from the Honda Civic repair manual, is 30 to 35 PSI.
We can connect a fuel pressure gauge to the fuel system using an adapter that connects to the fuel filter's banjo bolt (see photo above). You can see a photo of the fuel filter's banjo bolt here: Location Of The Fuel Filter's Banjo Bolt.
NOTE: If you don't have a fuel pressure gauge, take a look at the section: Where To Buy A Fuel Pressure Test Gauge.
OK, let's get started with this test:
Place a shop towel around the fuel filter's banjo bolt. The shop towel's job is to absorb any fuel that may leak when doing step 2.
Remove the 6mm bolt located on top of the fuel filter's banjo bolt..
Now, screw the fuel pressure test gauge's adapter in the 6mm bolt's hole (on the banjo bolt).
NOTE: You don't have to remove the banjo bolt from the fuel filter if you have the small 6mm adapter. If you're using a test gauge kit without the 6mm adapter and instead using an adapter the same size as the banjo bolt, then watch out for the 2 copper washers that are used on the fuel filter's banjo bolt. As you remove the banjo bolt, be careful they don't fall and get lost since they're the ones that seal the fuel within the connection.
When ready, ask your helper to cycle the key on and off but don't crank the engine while you observe the fuel pressure tester's gauge.
Check the connection at the fuel filter for fuel leaks and if any, eliminate them.
Your fuel pressure gauge should register: 30 to 45 PSI with the Key On Engine Off (KOEO) if the fuel pump is OK.
Let's take a look at what your results mean:
CASE 1: If the fuel pressure gauge registered 0 PSI. This confirms that the cause of your 1.5L Honda Civic engine's no-start problem is caused by a lack of fuel.
Now, I usually take one more precaution, before condemning the fuel pump as bad and this is to check that the fuel pump is getting 12 Volts as the engine is cranking. This is just to make sure that the fuel pump relay and fuse are OK and doing their job.
What you'll have to do to accomplish this is to attach a multimeter in Volts DC mode to the wire that supplies this voltage to the fuel pump and while a helper cranks the engine, verify that the fuel pump is getting this power. If the 12 Volts are being supplied to the fuel pump, you have now 100% verified that the fuel pump is fried and needs to be replaced.
The following wiring diagram will help you locate the fuel pump fuse: Fuel Pump Circuit Wiring Diagram (1993-1995 1.5L Honda Civic).
CASE 2: If the fuel pressure gauge registered 30 to 45 PSI: This fuel pressure gauge result lets you know that the fuel pump is working and delivering enough fuel to the fuel injectors. The reason your 1.5L Honda Civic is not starting is due to another reason. The fuel pump is OK.