Test Driving...

[JBHandJr]

Well, I've brought home a 2008 Ranger Ext Cab XLT 4x4 w/26k miles. Seems pretty solid but it has a VERY high pitched whine at idle and isn't rpm dependent. If I begin to move, I can hear it until about 10 mph. I don't believe that its going away, but wind/engine/etc. noise is covering it up.

Another note, if I turn the key to on, without starting the engine, I can hear the whine. I believe its fuel pump related but not sure.

Is this an "normal" noise? If it isn't, is the fuel pump on the way out? Any way to test it?

Thank you,
-Barry Hand-

P.S. Sorry this is my first post. I did a search and I've been lurking, but haven't come across this particular question.

 

[RonD]

The Fuel pump will come on with the key but only for 2 seconds, to prime the fuel rail, then it will shut off until engine is running.
So if whine doesn't stop after 2 seconds it is not the fuel pump.

I assume you have played with the radio and the whine is not from a speaker, bad electronics in amps can generate any frequency even with radio off.
You could try pulling fuses, with key on and see if any shut off the whine, then track it down.

 

[wildbill23c]

If you are turning the key on and not starting the engine and are still hearing the whining noise constantly it could be your blower motor for the heater/AC. Mine what making horrendous noises in my Bronco 2 no matter what I did regardless of fan speed setting it would howl continuously. Try turning off your heater/AC system completely including the fan and see if you still get the same noise. Its not going to be vehicle speed or engine speed dependent if its the fan.

 

[JBHandJr]

To be more clear...

When the key is turned to on, without starting, the noise is only there for ~2 seconds. This is probably priming the fuel rail.

Once the truck is started, the noise is present the entire time. It doesn't change with rpm, speed, etc.

When I crawl under the truck, I can hear it sounding like its coming from the fuel tank. All of this is why I believe its the fuel pump.

However, since it sounds more like a whistle/squeal than a mechanical grind/squeak, I'm wondering if the fuel pump could have a loose vacuum hose or something similar. I'm not familiar with the functions of the fuel system so not sure.

 

[RonD]

I would start the engine then pull the Fuel Pump Fuse for a few seconds then put it back in, so test it noise is the fuel pump.

The fuel pump should not be on all the time, the computer primes the system then once engine starts it turns fuel pump on and off based on TPS(throttle), RPM and Speed.
So engine will continue to run with fuel pump fuse removed, but it would eventually stall.
Fuse and Fuel pump relay are in the engine compartment Power Box

EVAP system leak would turn on the CEL(check engine light).