Sooner or later the fuel pump is gonna' fail in your 3.2L Isuzu Rodeo and when it does, it's either not going to start or it'll start and run but it'll run with a lack of power.
The cool thing is that testing the fuel pump is not hard and in this tutorial I'll explain how to test the fuel pump's pressure with a fuel pressure gauge.
Contents of this tutorial:
- Symptoms Of A Bad Fuel Pump.
- Where To Buy The Fuel Pump And Save.
- TEST 1: TEST 1: Fuel Pressure Test (Engine Does Not Start).
- TEST 2: Fuel Pressure Test (Engine Starts).
- TEST 3: Checking The Fuel Pump Fuse.
- TEST 4: Using Starting Fluid To Confirm Lack Of Fuel.
- Where To Buy A Fuel Pressure Test Gauge.
- More 3.2L Isuzu Diagnostic Tutorials.
APPLIES TO: This tutorial applies to the following vehicles:
- 3.2L V6 Isuzu Rodeo: 1993, 1994, 1995.
- 3.2L V6 Honda Passport: 1994, 1995.
Symptoms Of A Bad Fuel Pump
Your 3.2L Isuzu Rodeo's engine needs 3 things to start and these are: air, fuel and spark. It's the fuel pump's job to provide the fuel the engine needs.
Over the years I've noticed that fuel pumps usually fail in one of two ways. In the most common type of failure I've seen, the fuel pump fails completely and it stops sending fuel to the engine. This causes the engine to crank but not start due to a lack of fuel.
In the other type failure, the fuel pump still works but it sends only just enough fuel to start the engine but not enough to keep it running optimally.
This type of failure causes one or more of the following symptoms.
- Engine backfires when you accelerate the vehicle on the road.
- Engine take a long time to start.
- Engine knock when accelerating the vehicle on the road (due to a lean air/fuel mixture).
What makes testing the fuel pump so easy is that your 3.2L Isuzu Rodeo has a Schrader valve to which we can connect a fuel pressure gauge to and see if the fuel pump is actually providing fuel to the fuel injectors.
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:
All of the fuel pump pressure test kits above have the fitting that will connect to your Isuzu's Schrader valve.
TEST 1: Fuel Pressure Test (Engine Does Not Start)
If the fuel pump fails, your 3.2L V6 Rodeo (Honda Passport) is not going to start due to a lack of fuel to the fuel injectors.
The cool thing is that testing the fuel simply involves connecting a fuel pressure test gauge to the Schrader valve that's on the fuel injector rail and then the engine is cranked.
If the fuel pump is OK (and not behind the no-start problem), you'll see a fuel pressure of 41-46 PSI on the fuel pressure test gauge.
If the fuel pump is bad (and thus causing the no-start problem), you'll see a fuel pressure of 0 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.
Connect the fuel pressure gauge to the Schrader valve.
Crank the engine.
Your fuel pressure gauge should register: 41 to 46 PSI.
Let's take a look at what your results mean:
CASE 1: The fuel pressure gauge registered 0 PSI. This confirms that the fuel pump is not functioning.
This test result usually means that the fuel pump is bad and needs to be replaced. But before you do, you need to check that the fuel pump fuse isn't blown. Go to: TEST 3: Checking The Fuel Pump Fuse.
CASE 2: The fuel pressure gauge registered 41 to 46 PSI. This is the correct and expected test result.
CASE 3: The fuel pressure gauge registered a pressure less than 41 PSI. This test result tells you that the fuel pump is failing.