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Discussion Starter #1
today i started my truck and i heard an annoying whining from the back im guessing its from the fuel tank, which would be the fuel pump thats about to crap out on me, right? and it also goes under 500RPMs for mabey 3 seconds then it goes back to normal for a little bit and then it will die down again then back to normal, coud i drive like this with out it dieing on the street, thanks guys for any help.
 

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I'd check for corroded wiring first.

Richard
 

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Typically, when you turn your key (but not crank the truck), your fuel pump will prime. I've had about 5 Rangers over the years and every one of them has had the same issue with the RPM's dropping and then jumping back up.

I noticed that mine does it a little more frequently when it is less than 60 degrees outside.
 

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Can you check your fuel pressure regulator?

Richard
 

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Could it be that you have the defroster on, which runs the A/C compressor? Then the idle will go up for 5-15 seconds and then come back down. It just keeps cycling this way as long as you have the defroster or the A/C on. Or in my case it also runs the compressor when its on the head/ foot setting, which it should not operate that way at all. My truck also idles around 600-700 rpm with no throttle so 500 rpm doesn't seem out of the picture for being normal. I am just trying to get the easy, cheap stuff out of the way just so you don't possibly have to waste money on a part that was working perfectly normal.
 

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Discussion Starter #6
i knew that you could hear the fuel pump prime but ive have never heard it that loud before and yea it did that at night when it was a little colder than ussual out and i have drivin it up and down the street latley and it hsnt been that loud ever since that night, so mabey it was just cold out, but thanks guys i realy didnt want to drop the tank out or lift the bed off so you guys saved me alot of time.
 

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when your a/c is lower on freon it will turn on and off non stop no matter what is on meaning the heater a/c anything. try to unplug the a/c compressor and see if that works.
 
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