It's 10pm - where's your lift pump?

Bill.Barg · **Posted:** Wed Apr 09, 2008 8:39 pm

See pictures at

http://picasaweb.google.com/bill.barg/J ... 6132120066

Notes:

The 50 mph stutter, 1700 rpm with TC cluch locked no longer happens. This is great, and the major objective of the upgrade for me.

Fuel gauge reads 25% over. I am concerned that the "low fuel " light will not come on at 1 gallon left. With 16 gallons, the gauge reads full. I will probably drop the tank after it empties to bend the float up a bit. I would rather it show empty early than too late. Is there a way to ajust this electronically ?!?

The 25 second pump run with ignition switch on works. Purging the system was a snap.

The manual purge pump is ROCK HARD, for the first time ever. May never be used again, !

Replacing the whole harness was easy. Probably easier than feeding 2 wires through the exisiting harness.

The 06 gasser harness is 4 inches shorter than the CRD harness at the tank connector. This was not a problem. The ABS sensors are identical lengths

There is a mounting hole for the ground wire under the seat near where the connector mounts to the body.

There are two holes in the body frame, ready for the push in mounting clips included in the 06 gasser harness 14 pin connector.

No black smoke or othe problems with WOT (MR MOPAR early concern).

Whirring sound of pump running during start up sounds great!

Bill

gmctd · **Posted:** Wed Apr 09, 2008 8:45 pm

You can unclip the CRD fuel sender from the Jeep module, swap it in for the sender in the Dodge module - ours was identical, no offset indicated, so pump and sender are Dodge - plus, ours was pre-owned, so may have been tweaked at the factory

Bill.Barg · **Posted:** Wed Apr 09, 2008 10:20 pm

The fuel float assembly and housing and electronics were identical in the two units I have, except for the position of the tab on the mounting ring.
I think that maybe the 20 deg rotation might have made the float arm rest on some feature in the tank?

EDIT this was proven wrong. Th float sits lower and needs to be bent to correct it.

Edit again. No bend needed. use original float on new unit

crdjon · **Posted:** Wed Apr 09, 2008 10:31 pm

If thats the case, is it worth considering bending the float arm around approximately 20 degrees to compensate, my pump should be here today, just trying to source a cable for it so if you can suggest anything to avoid the fuel level discrepancy Id appreciate it.

honey_don't · **Posted:** Wed Apr 09, 2008 10:36 pm

With the Cummins pump, ours goes about 60 miles after fillup before the needle begins to move. Never noticed what it did prior, only ever filled it three times after purchase before pump install.

05infernoCRDL · **Posted:** Wed Apr 09, 2008 10:43 pm

just a thought here.. the fuel sender sends a signal equal to the resistance right?
couldn't one take the resistance of the old fuel sender before removal.. and adjust
the float in the new sender to equal the resistance of the old sender? before
everything is all bolted back up?

gmctd · **Posted:** Wed Apr 09, 2008 10:48 pm

Bottom of the tank is flat, nothing to block the float arm - anyway, that would only effect the first 1/16th tank, would be accurate above that - place the Jeep and the Dodge modules side-by-side, as I did in the early part of this thread - you should be able to determine any discrepancy there - the offset from 90deg shouldn't make any difference, as the guage is damped

crdjon · **Posted:** Wed Apr 09, 2008 10:56 pm

My new pump module WITH PUMP just arrived all the way from good ol USA...... he he he :lol:

gmctd · **Posted:** Thu Apr 10, 2008 3:00 am

Good - now, take it to the dealer, show it to MrMoparts, tell him\her you need the mating connector and terminals - they usually carry the connectors with pigtails in stock

Scott Langohr · **Posted:** Thu Apr 10, 2008 7:26 am

I got my pump and '05 gasser harness yesterday. I did not have time to really study it but, on first inspection, the wires that go to the pump plug all appear to be the same size wire. I was of the understanding that the 12V power wire would be a larger guage wire. If they all are the same size, should I replace the 12V power and ground with a larger guage wire? It would not be to bad to do since I can cut the harness wires and use them to pull through the new wires but the wire color would be different. If I use the gasser harness and remove the CRD harness, wouldn't all 4 pump wires have to be extended or is the extention only required if transfering the gasser wires to the CRD harness? The wires in the harness look pretty small. What guage wire would be required to run the pump?

05infernoCRDL · **Posted:** Thu Apr 10, 2008 10:00 am

scott,

the wires i got from a forum member were smaller than the 16 AWG
that i bought at the hardware store... i am talking the actual wires
the insulation was about the same size.. if you want i can take a pic.

gmctd · **Posted:** Thu Apr 10, 2008 10:05 am

Use the factory-engineered wiring as-is - they spec'ed it for an even more powerful lift-pump motor in the 56psig V6 system, so should be suitable - don't be surprised if the CRD rear-cabin wiring is larger, tho

Joe Romas · **Posted:** Thu Apr 10, 2008 10:36 am

Back on page two the third or so picture down shows a different angle on the float rod. That may be the reason for the fuel guage being off :lol:

Bill.Barg · **Posted:** Thu Apr 10, 2008 11:35 am

gmctd wrote:

Bottom of the tank is flat, nothing to block the float arm - anyway, that would only effect the first 1/16th tank, would be accurate above that - place the Jeep and the Dodge modules side-by-side, as I did in the early part of this thread - you should be able to determine any discrepancy there - the offset from 90deg shouldn't make any difference, as the guage is damped

Okay, the arm is not resting on something

see

http://picasaweb.google.com/bill.barg/J ... 2629303858

for the modules side by side... cant see any geometry difference

and this for a top view

http://picasaweb.google.com/bill.barg/J ... 1219238466

Gmctd... what do you mean by "damped"?

Scott Langohr · **Posted:** Thu Apr 10, 2008 1:19 pm

05infernoCRDL wrote:

scott,

the wires i got from a forum member were smaller than the 16 AWG
that i bought at the hardware store... i am talking the actual wires
the insulation was about the same size.. if you want i can take a pic.

Think I will do as told and use them as they are. I still wonder if there is any reason to lengthen the 4 Pump wires if using the gasser harness. If there is plenty of slack to allow the tank to drop I won't mess with it.

Thanks

gmctd · **Posted:** Thu Apr 10, 2008 1:28 pm

Joe, the background cardboard and plastic bag were not smooth, flat, and even-surfaced during the shoot, plus positional viewpoint and camera angle can create wonders with optical illusion - someone in-process with new module could verify any difference(s)

The fuel guage is damped, Bill, so you don't see the continual variation as the fuel sloshes around in the tank - side-to-side fuel level variation would be greater than front-to-rear variation - f\r fuel level variation would be more rapid than s\s variation - the slight Dodge module offset would not be otherwise noticeable - in any event, compare the new Dodge module to the Jeep module B4 installation, would be my rec

Our pre-owned install returned same fuel level as the oem module - you could also just pop-out the Jeep sender, pop it in the Dodge module, connect the fuel lines and wiring, raise the tank, keeping it level, try it B4 initiating reassembly procedures

Bill.Barg · **Posted:** Fri Apr 11, 2008 1:34 am

I tested the CRD fuel gauge sender, now that it is on my bench instead of in the tank.
It has a variable resistor moved by float;

full = 25 ohm
empty = 200 ohm

This turns out to be good news, since I want the gauge to read "more empty" which is greater resistance.
Assuming the dodge system sender is similar;
I will put an in-line trimmer (variable resistor) on one of the gauge wires near the connector under the seat.
I know that i can get 19.0 gallons x 21.5 mpg = 408 miles with 1.5 gallon to spare. I want the low fuel light to come on at this point. I will adjust the trimmer to make the gauge read lower and set off the low fuel light at this point.

I believe this is better than bending the float arm, since it is much easier to adjust, real time.

waddaya think?

gmctd · **Posted:** Fri Apr 11, 2008 2:32 am

The Dodge sender is identical in form, function, color, and resistance..................

First, note the fuel guage position, key ON
- then, key OFF, unplug and measure the resistance of the in-tank sender at the connector under the seat, compared to your estimate of the actual fuel level
- then, measure the sender in your hand, moving the float till you have the exact same resistance
- note the float level position, see if that agrees with your estimate or the actual in-tank sender position, then connect it to the cabin harness, noting the fuel guage indication with key ON
- that should give you enuff data to figger it out

- anyway, if you electrically offset the basic sender resistance, it will be offset from 200ohms to 25ohms - for example, 220ohms@200ohms will be 45ohms@25ohms, etc.

Bill.Barg · **Posted:** Fri Apr 11, 2008 9:55 am

GMCTD,

Ya, I like the idea of measuring the installed unit resistance for reference.
I am still left with estimating the Actual amount of fuel in the tank at the time from eyeballling the float position.
I want the light to come on with 1.5 G. that means, ideally, I need to know when there is 1.5 G of useable fuel left in the tank at the time of calibration. I dont think I can get this by looking at float position, can I?

I realize that putting in a resistance offset will not cure the nonlinearity problem (showing FULL for about 1/4 tank, etc)
but like I said, i am just trying to recover the low fuel warning functionality.
I wonder how this will effect the EVIC estimate of fuel available and subsequently its estimate of range?!?

I will be getting the electronic parts today

Bill

gmctd · **Posted:** Fri Apr 11, 2008 10:49 am

Any additional resistance in the circuit will effect the guage indicator position from Empty to Full - has nothing to do with linearity, which is equally dividing the tank into 'quadrants' - the resistive element is linear

By using the CRD sender in-hand, connected to the rear cabin harness, you can vary the float positon to see when the LFL indicator is triggered ON, noting that position - using general previous mpg to estimate current in-tank fuel level, compare the readings - to fix, I'd rec dropping the tank at ~5gals, either install the CRD element, or alter the new float arm to match - no telling what indecencies the new module endured since leaving the production line, in-transit

note: caution - when testing in-vehicle, remove Lift Pump Fuse or Relay in the power panel under the hood to disable lift pump operation

It's 10pm - where's your lift pump?

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