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4JG2 fuel pump.

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4JG2 fuel pump.

Postby MU31TD » Tue Nov 12, 2013 3:12 pm

97 Jackaroo 4JG2.

Red Circle is supposedly fuel adjustment

What is this bolt circled in yellow? It is covered with aluminum (or tin) cap similarly to the fuel adjuster from factory.

4JG2 fuel pump.jpg
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MU31TD
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Re: 4JG2 fuel pump.

Postby MU31TD » Tue Nov 12, 2013 3:20 pm

In this post is a picture of my late MU with 4JG2 where there is same bolt.

viewtopic.php?f=19&t=824

Note: Old MU was smashed in an accident. NRMA wrote it off due to structural damage, but Engine was fine at the time.
MU31TD
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Posts: 55
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Country: Australia
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Vehicle: Now: 97 Jackaroo 3.1 4GJ2 Manual
Past: 1994 Isuzu MU 3.1TD Auto

Re: 4JG2 fuel pump.

Postby isuzurob » Tue Nov 12, 2013 6:58 pm

yellow= is fuel adjustment, red= is base idle screw, when you wind fuel screw the idle increases so have to adjust base idle
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Re: 4JG2 fuel pump.

Postby MU31TD » Wed Nov 13, 2013 9:50 am

isuzurob wrote:yellow= is fuel adjustment, red= is base idle screw, when you wind fuel screw the idle increases so have to adjust base idle


Shiester! you are right I marked them backwards. That's right I now remember my MU's idle was low when i bought it. Idle then got to normal after adding fuel. I didn't need to adjust idle on MU but will need for the Jacka.

Thanks!

Found this for On-Boost adjustment: http://dodgeram.org/tech/dsl/more_power/Power_ve.htm

MU's pump had a screw at the top of actuator for On-Boost adjustment. Very easy to tune and only needed a notch to add black smoke and 80 deg C on EGT. But only noticeable up a steep hill at 1.1Bar Also makes power another 100RPM further.

On Boost may be touched ONLY with EGT.

Will play around if I get time on weekend.
MU31TD
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Country: Australia
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Past: 1994 Isuzu MU 3.1TD Auto

Re: 4JG2 fuel pump.

Postby 1Bighorn2nv » Wed Mar 25, 2020 6:06 pm

Fuel adjustment screw.help please
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Re: 4JG2 fuel pump.

Postby isuzurob » Wed Mar 25, 2020 7:22 pm

First pic it's the threaded rod with the lock nut on it, below the fuel return banjo
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Re: 4JG2 fuel pump.

Postby 1Bighorn2nv » Wed Mar 25, 2020 7:31 pm

Yeah thought so and problem is if I adjust revs rise how do I turn revs down?
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Re: 4JG2 fuel pump.

Postby isuzurob » Thu Mar 26, 2020 12:38 pm

Have to wind out the stop screw at the front of the fuel pump where the fuel feeds into the pump, pull the throttle cable and you will see the throttle plate hit it
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