Sooner or later, the fuel pump in your 3.0L equipped Ford Ranger (or Mazda B3000) is gonna' fail. And let me tell you that testing it is not hard.
In this tutorial I'll explain the 2 methods you can use the test to see if the fuel pump is behind your Ford's no start condition. I'll also explain how the fuel pump pressure test can help you find out if the fuel pump is behind a lean condition causing a lack of power on your vehicle.
Contents of this tutorial:
You can find this tutorial in Spanish here: Cómo Probar la Bomba de Combustible (3.0L Ford Ranger) (at: autotecnico-online.com).
Symptoms Of A Bad Fuel Pump
The fuel pump can fail in one of two ways. The first type of failure is a complete failure in which the fuel pump stops sending fuel to the fuel injectors. The other type of failure is a fuel pump that's working but NOT sending enough fuel to the fuel injectors and thus provoking all kinds of performance issues.
When a fuel pump completely fails, 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.
- Fuel pressure PSI is 0 PSI at the Schrader valve test port.
- 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.
TEST 1: Using Starting Fluid To Confirm Lack of Fuel
Although using starting fluid, to check a no start, is not the most accurate way to test the fuel pump... it's the fastest way to jump start your troubleshooting efforts.
I've been using the starting fluid test, to diagnose a lack of fuel causing a no start problem, ever since I've been working on cars professionally but let me tell you that the successful outcome of this test depends on making sure that all 6 cylinders are getting spark.
This means that, to get an accurate test result, you have to first check all (or at least the majority of) cylinders for spark test with a dedicated spark tester before you perform the starting fluid test.
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.
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: 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.