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Unread 06-06-2014, 07:25 PM   #1
calijeepin96
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1996 ZJ 
 
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fuel pump

ive looked for a fuel pump wiring diagram but no luck any helps im trying to see why my gas gauge is reading full or empty all the time pics hepful thanks

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Unread 06-06-2014, 09:22 PM   #2
ZeeJay1997
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Unread 06-06-2014, 09:41 PM   #3
calijeepin96
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i need the one that tells me what pin on the conector is to what
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Unread 06-07-2014, 05:57 AM   #4
ZeeJay1997
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the dashed boxes represent a portion of an assembly,
the solid boxes represent a complete assembly.
The lines on the drawings represent wiring,
the number or letter at the intersection of the assembly and the wire gives the pin number.
the carat/arrow thingies <<--^^ mean there is a connector.
the pin numbers on the drawing relate to a number that is on the connector.

c1 is the black connector on the pcm. c3 is the white connector.

the S numbers are splices and the G numbers are grounds.
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Unread 06-07-2014, 09:58 AM   #5
calijeepin96
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ok but the just what the 4 pins from the fuel pump is what i want to find out
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Unread 06-07-2014, 10:33 AM   #6
AVR2
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These are the only pinouts I have for the fuel pump connector. Note that on the 93-96 pumps, if the fuel level sending unit is bad you have to replace the entire fuel pump assembly.

You are looking for 220 ohms when empty, 20 ohms when full.

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Unread 06-07-2014, 10:44 AM   #7
ZeeJay1997
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WARNING: never ohm out a fuel sending unit while it is installed in the fuel tank. KABOOM!
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Unread 06-07-2014, 11:07 AM   #8
calijeepin96
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thanks. its a fuel pump or unit that i got for cheap off line but i dont know if its my gauge or unit that is making my gauge full all the time or empty all the time i got the jeep with a bad fuel pup n not running
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Unread 06-07-2014, 11:07 AM   #9
calijeepin96
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Quote:
Originally Posted by ZeeJay1997 View Post
WARNING: never ohm out a fuel sending unit while it is installed in the fuel tank. KABOOM!
how would you ohm it out
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Unread 06-07-2014, 11:47 AM   #10
ZeeJay1997
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Quote:
Originally Posted by calijeepin96 View Post
how would you ohm it out
Remove it from the tank and use the picture AVR posted
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Unread 06-07-2014, 12:37 PM   #11
calijeepin96
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will do give me a few and i will let you know what it reads
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Unread 06-07-2014, 02:10 PM   #12
AVR2
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Quote:
Originally Posted by ZeeJay1997 View Post
WARNING: never ohm out a fuel sending unit while it is installed in the fuel tank. KABOOM!
Is there really an explosion risk? After all, there's voltage on those wires in normal use, and you can throw a lit match into a fuel tank and it won't explode - it'll burn, sure, but it won't actually explode.
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Unread 06-07-2014, 03:27 PM   #13
ZeeJay1997
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Quote:
Originally Posted by AVR2 View Post
Is there really an explosion risk? After all, there's voltage on those wires in normal use, and you can throw a lit match into a fuel tank and it won't explode - it'll burn, sure, but it won't actually explode.
there is no voltage on the sending unit contacts. a PCM circuit reads the ground potential and determines the signal to send on the CCD bus.

when you use an ohmmeter, it creates a circuit across the wiper arm. there is a risk that the meter circuit creates a spark in a vacant space, which is more likely to cause an explosion.
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Unread 06-07-2014, 06:04 PM   #14
calijeepin96
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so it reads normal now what to test
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Unread 06-07-2014, 07:40 PM   #15
ZeeJay1997
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you need to figure out how to use the diagram i posted to verify the circuit from the pcm to the fuel pump connector and back to the pcm.

If the PCM detects a short or open in the fuel level sending unit circuit, it sends a message on the CCD data bus that will cause the instrument cluster circuitry to position the fuel gauge needle at the Empty stop.

if the circuit checks out okay, the gauge may be bad.
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