The fuel pump, in your 3.0L Ford, can be easily tested with an inexpensive fuel pressure test gauge. This is due to the fact that your 3.0L V6 equipped Ford Taurus (Mercury Sable) comes equipped with a Schrader valve and it's to this valve that the fuel pressure test gauge is connected to.
In this tutorial I'm also gonna' explain the simple ‘starting fluid’ test, which is a quick way to confirm a lack of fuel problem causing a no-start problem.
Contents of this tutorial:
NOTE: This tutorial applies to the 3.0L OHV (Over Head Valve) V6 engine only. You can confirm this by checking the 8th digit of the VIN number. If your 3.0L is OHV, the 8th VIN character will be a letter U.
You can find this tutorial in Spanish here: Cómo Probar La Bomba de Gasolina (1990-2000 3.0L Ford Taurus) (at: autotecnico-online.com).
Symptoms Of A Bad Fuel Pump
The 2 most common fuel pump failures are a complete failure in which the fuel pump stops sending fuel to the fuel injectors or a fuel pump that is sending a volume that's lower than normal to the fuel injectors (provoking a lean air/fuel mixture).
Obviously, when the fuel pump completely fails, your 3.0L Ford Taurus 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 feeding spark to all 6 cylinders.
- The PCM will still pulse (activate) all 6 fuel injectors.
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.
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 adapter to tests all 3.0L Fords:
All of the fuel pump pressure test kits above have the fitting that will connect to your Ford's Schrader valve.
TEST 1: Checking Fuel Pressure With A Fuel Pressure Gauge
In this section we'll use a fuel pressure test gauge to find out if the fuel pump is creating the factory specified pressure.
Using a fuel pressure gauge comes in handy in diagnosing either a no-start condition or lean air/fuel mixture caused by a under-performing fuel pump.
The fuel pressure specifications with the key on engine off (KOEO) and key on engine running (KOER) are:
|1990-1993||35-40 PSI||30-45 PSI|
|1994-1995||40-43 PSI||35-38 PSI|
|1996-1998||35-40 PSI||30-45 PSI|
|1999-2000||37-43 PSI||26-45 PSI|
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 Schrader valve. The shop towel's job is to absorb any fuel that may leak when doing step 2.
To see the location of the Schrader valve, go here: Location Of The Schrader Valve.
Connect the fuel pressure gauge to the Schrader valve on your 3.0L Ford Taurus's fuel injector rail.
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 Schrader valve for fuel leaks and if any tighten the fuel pressure a bit more (by hand only) to eliminate them.
Your fuel pressure gauge should register the specified KOEO fuel pressure for the particular year of your 3.0L Ford in the table above 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 3.0L Ford Taurus no-start problem is caused by a lack of fuel.
Now, before condemning the fuel pump as bad, you should:
- Make sure the fuel pump inertia switch hasn't tripped (if it has tripped, then the fuel pump will not run). To see what the fuel pump inertia switch looks like, go to: Fuel Pump Inertia Switch.
- Make sure the fuel pump relay is feeding the fuel pump power (if the fuel pump relay is bad, then the fuel pump will not run).
CASE 2: If the fuel pressure gauge registered the specified fuel pressure for your vehicle's model year. This test result lets you know that the fuel pump is working and delivering enough fuel to the fuel injectors. The reason your 3.0L Ford Taurus is not starting is due to another reason. The fuel pump is OK.