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whining noise form fuel rail???????help

C

cdean1

NAXJA Forum User
Location
Bakersfield
93 xj 4.0ho I get a whining form the fuel rail. It starts after it warms up and gets progressively louder. I sprayed carb cleaner on all the vacuum lines and no change in idle. i was thinking maybe an injector. i think i can isolate what area it is coming from and figure out what injector it is. Will an injector make a whine if it is going out? Anyone got any other ideas? Thanks for the help
 
Last edited:
Sometimes the use of a mechanics stethoscope can be helpful as isolating noises can be tricky. Be careful when poking around a running engine.

Be sure that the whine is not coming from a component along the serpentine belt route (alternator, etc).

I've not heard an injector whine but anything is possible.

Let us know what you find.
 
IIRC, you also have the fuel pressure relief valve that lets excessive fuel pressure return to the tank. I would check that out to see if that is making the noise. They have a vacuum diaphram. You could try pinching or disconnecting the vacuum line to see if the noise changes. Don't do it for too long as it will make your XJ run rich.
 
I don't have a '93, but it should be right on the fuel rail. You should haved one fuel line incoming and one returning to the tank. The pressure relief valve allows excess fuel to return to the tank. It should also have a vacuum line going to it. Later models just have one in the tank with no return line.
 
nope not the fuel pressure valve going to buy a new injector on sat. when i block the noise with my hand the sound isolates to one injector sooo...unless someone can think of something im making the $50 gamble:dunno:
 
sooooo...not the injector. changed it and still whinning. but in the process i found that the noise comes on when the ac or heater is on. it has been so cold its been on all the time. not on vent just ac or heater anybody have that problem before?????
 
Are you sure its from the fuel rail?

Impromptu stethoscope:

Get a 3/8 extension, about 12" or so, push the male end on component you want to check, then listen/feel for offending vibration.

Good luck?
 
cdean1 said:
sooooo...not the injector. changed it and still whinning. but in the process i found that the noise comes on when the ac or heater is on. it has been so cold its been on all the time. not on vent just ac or heater anybody have that problem before?????
Click to expand...

The air conditioning compressor runs when you are in "defrost. (doesn't run in regular heat mode) If this noise occurs when either AC or defrost is on, suspect the air conditioning compressor.

Isolate with either a mechanics stethoscope (cheap at most parts stores) or make your own as mentioned with a dowel, extension, etc.
 
I use a mechanic's stethoscope for running down internal noises and my Shop Vac hose for external noises. I put the big end over my ear and the small end near or on the components. The small end is small enough to get in tight places and if I hit a running fan blade or such there's little risk of injury. Looks kind of silly but it works.
 
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