How To Test The Fuel Pump (1995-1998 3.8L V6 Ford Windstar)

Checking fuel pump pressure is pretty easy on the 1995-1998 3.8L V6 Ford Windstar. In this tutorial, I'm going to show you exactly how to do it, step by step.

With your test results, you'll quickly figure out whether the fuel pump is behind an engine performance issue or a no-start problem.

I'll also explain how to do a starting-fluid test to confirm the no-start is caused by a fuel delivery issue.

APPLIES TO: This tutorial applies to the following vehicles:

• 3.8L V6 Ford Windstar: 1995, 1996, 1997, 1998.

Symptoms Of A Bad Fuel Pump

Over the years, after working on a ton of engine no-start and performance issues, I've noticed that fuel pump problems usually cause one of two things:

• An engine no-start problem —this happens when the fuel pump completely fails and no longer delivers fuel to the injectors.
• Engine performance issues —in this case, the fuel pump still delivers enough fuel to start the engine, but not enough to keep it running smoothly.

Now, if the fuel pump is still working but underperforming, you'll notice one or more of the following engine performance problems:

• 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 minivan down the road.

Whether your 3.8L V6 Ford Windstar is dealing with an engine performance issue or a no-start problem, checking the fuel pump's pressure is one of the go-to tests you've got to do to properly diagnose the cause of the issue.

Where To Buy A Fuel Pressure Test Gauge

The fuel pressure test kits linked below have everything you need to get the job done. First, they include the adapter needed to connect to your Ford Windstar's Schrader valve. Second, they won't cost you an arm and a leg. And third, they're reliable tools that'll help you troubleshoot the fuel pump:

Fuel Pressure Specifications

1995-1998 3.8L V6 Ford Windstar fuel pressure specifications with the key on engine off (KOEO) and key on engine running (KOER) are:

Year	KOEO	KOER
1995	35-40 PSI	30-45 PSI
1996-1998	30-45 PSI

TEST 1: Checking Fuel Pressure With A Fuel Pressure Gauge

OK, as I've already mentioned, we're going to connect our fuel pressure test gauge to the fuel pressure test port —commonly known as the Schrader valve.

Depending on whether your Windstar is a 1995 model or a 1996-1998 model, the Schrader valve will be in a slightly different location on the fuel injector rail.

You can find the Schrader valve in the following locations:

• 1995: Located on the fuel injector rail right where the fuel lines connect to the rail (see photo 2 of 3).
• 1996–1998: Located on the fuel injector rail for cylinders 4, 5, and 6 (under the plenum, but still very accessible) —between the fuel injectors for cylinders 4 and 5 (see photo 3 of 3).

NOTE: If you haven't checked the fuel pump inertia switch to see if it's tripped, do that before checking fuel pressure. If the inertia switch has tripped, it'll cut power to the fuel pump, and you'll get a zero PSI fuel pressure reading. So if you haven't done that yet, go ahead and check it —and reset it if necessary: Fuel Pump Inertia Switch.

OK, let's get started with this test:

1. 1

   Disconnect the ignition coil pack from its connector.
   
   This will keep the engine from starting while checking the Key On Engine Off (KOEO) fuel pressure.

2. 2

   Place a shop towel around the Schrader valve.
   
   The towel's job is to absorb any fuel that may leak during the next step.

3. 3

   Connect the fuel pressure gauge to the Schrader valve on the fuel injector rail.

4. 4

   Check for fuel leaks at the gauge connection point (the Schrader valve) by having your helper cycle the key ON and OFF —but don't crank the engine.
   
   NOTE: If you see any leaks, tighten the gauge connection slightly by hand to stop them.

5. 5

   Have your helper crank the engine while you observe the fuel pressure gauge.

6. 6

   The fuel pressure gauge should register the specified KOEO fuel pressure.

Let's take a look at what your results mean:

CASE 1: Fuel pressure is 0 PSI. This tells you that fuel isn't reaching the injectors —and that's why your Ford Windstar's engine isn't starting.

The most likely cause of this 0 PSI fuel pressure reading is a bad fuel pump. Still, if I were in your shoes, I'd do one more thing: make sure the fuel pump fuse and relay are OK and delivering power to the pump.

Making sure the fuel pump is getting power is an easy check, and I'll show you how to do it in this tutorial: Power To Fuel Pump Check (1991-1999 3.8L V6 Ford Windstar, Mercury Sable).

CASE 2: The fuel pressure is below specification. This test result tells you the fuel pump is failing. Any fuel pressure below spec will cause engine performance issues, so your next step is to replace the fuel pump to get your Ford Windstar back on the road.

CASE 3: Fuel pressure is within specification. If fuel pressure is within spec, you can conclude the fuel pump is working properly and delivering fuel to the injectors.

This rules out the fuel pump as the reason your Windstar isn't starting —or, if you're troubleshooting a performance issue, it means the fuel pump isn't the cause.

TEST 2: Using Starting Fluid To Confirm Lack Of Fuel

Using starting fluid to check if a fuel delivery issue is causing a no-start has been an old mechanic's trick for ages.

I still remember the first time I was taught how to do it —back when cars still had carburetors. Even today, with every vehicle equipped with fuel injection, this test is still a quick and effective way to kick off an engine no-start diagnostic.

Now, the most important thing to do before spraying starting fluid into the intake is to make sure the engine's getting spark. If you haven't checked for spark yet, it's crucial that you do that first.

Why check for spark first? Simple —you can't trust the outcome of this test unless you know for sure the engine's getting spark.

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.

FUEL PUMP INERTIA SWITCH CHECK: Your Ford Windstar comes equipped with a fuel pump inertia switch, designed to cut power to the fuel pump anytime the vehicle experiences an impact, like in a crash. However, this switch can trip pretty easily —sometimes just hitting a big pothole is enough to do it. So if you haven't checked it yet, go ahead and see if it's tripped. If it has, reset it, and your engine should start right up: Fuel Pump Inertia Switch.

OK, let's get going:

1. 1

   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.

2. 2

   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).

3. 3

   Crank the engine once the air duct is back on and you're clear of the engine compartment.

4. 4

   You'll get one of two results with this test:
   
   1.) The engine will start momentarily and after a few seconds will die or.
   
   2.) The engine will only crank but not start at all.

OK, let's find out what your results mean:

CASE 1: The engine started and ran for a few seconds. You can conclude your Windstar's engine no-start problem is being caused by a fuel delivery problem —most likely a bad fuel pump.

Still, if I were in your shoes, I'd connect a fuel pressure gauge and verify fuel pressure. If there's no pressure, I'd also make sure the fuel pump is getting power.

CASE 2: The engine did not start, not even momentarily. If the engine doesn't start or run with starting fluid, that usually tells you a fuel delivery issue isn't behind the no-start problem.

Now, to be honest with you, the starting fluid test isn't the most accurate way to confirm a bad fuel pump. I'd still go ahead and hook up a fuel pressure gauge to make sure the pump is producing the specified pressure.

Fuel Pump Inertia Switch

Fuel Pump Inertia Switch Location by Model Year:

• 1995 Ford Windstar: Located behind the right-side kick panel. In case you're wondering what the heck the "kick panel" is —it's that trim panel right below the dash, between the dashboard and the floorboard, right next to the passenger door.
• 1996–1997 Ford Windstar: Located in the right rear area of the cargo compartment, behind the trim panel.
• 1998 Ford Windstar: Located behind the driver-side scuff panel, right below the hood release lever.

The fuel pump inertia switch is a mechanical safety device designed to cut power to the fuel pump in the event of a hard impact —for example, if your Ford minivan is involved in a crash. By cutting power to the pump, it prevents fuel from being sprayed in the event of a fuel line rupture, reducing the risk of a vehicle fire.

Now, even though the inertia switch is meant to shut off power during a heavy impact, it can also trip for other reasons. Slamming the passenger door too hard, hitting a curb, or even driving over a big pothole can sometimes cause it to trip.

So, anytime you're diagnosing an engine no-start problem, one of the first things you should do is check to see if the fuel pump inertia switch has tripped. Resetting it is simple —just press down on the button at the top of the switch. If it's been tripped, you'll feel a distinct click as it resets, letting you know it's ready to go.

More 3.8L V6 Ford Windstar Diagnostic Tutorials

You can find a complete list of 3.8L V6 Ford Windstar diagnostic tutorials in this index:

• 3.8L V6 Ford Windstar Index Of Articles.

Here's a sample of the diagnostic tutorials you'll find in the index:

• How To Test The MAF Sensor (1996-1998 3.8L V6 Ford Windstar).
• How To Test The TPS (1996-1999 3.8L V6 Ford Windstar).
• How To Test For A Blown Head Gasket (1995-2003 3.8L V6 Ford Windstar).
• How To Do And Interpret An Engine Compression Test (1995-2003 3.8L V6 Ford Windstar).