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Lift Pump – Tank Size - Hocus Pocus…
http://www.lostjeeps.com/forum/phpBB3/viewtopic.php?f=5&t=32755		 Page 1 of 1
Author:  Turbo Tim [ Fri May 23, 2008 5:57 pm ]
Post subject:  Lift Pump – Tank Size - Hocus Pocus…
Ok, I just did the lift pump install on my 2005 CRD but first I drove it until the gauge said empty and the fuel light was on. Out with the back seat and down with the tank. Surprise! There was about 3+ inches of fuel in the tank. Hmmmm. Next I checked the resistance between the two, (only at full and empty) and both new and old checked the same. Cut about ½ of the tab off so the float would be EXACTLY in the same spot as original. Did the wires, zip ties, etc. and finished the install. I also noted that one could just slip out the old float sensor assembly very easily and swap the two if I had to.

NOTE: Mine has some sort of check valve on the fill tube snoot on the tank. Possible for roll-over protection. There is no screen, but there is no way anyone is going to get a hose of any size through there. There are also little plastic “Vanes” protruding into the fill passage on the snoot of the fill spout on the tank to keep things away from the valve. Again, no hose is going to fit through there. (No stealing of fuel here).

I turned the key on and I could now hear a whirring sound coming from the back where it was once quiet before. Started it up and went for a drive.
My gauge said I had just under ¼ tank but above 1/8 tank! Before I was empty empty with fuel light on. Filled it up and it took exactly 18 gallons of fuel. (Reads full too and wallet is empty now).
So I go out an measure the height of my tank and it is a little more than 12 inches in height. The book says it is a 20.5 gallon tank. My math says that if the tank is 12 inches tall, then 3 inches would be ¼ tank, and that should be about 5 gallons. I believed that right up until I put 18 gallons in. So now either Chevron is selling smaller than normal gallons or my tank is larger than 20.5 gallons!
Only way to know for sure is to take it all out and start over some day.
I do believe at this time the ¼ tank and less calibration is different between the 2005 Cummings truck lift pump and our CRD’s with empty and full still being the same resistance.
This might explain what others are seeing.
Whoever does the next lift pump install, Please dump all the fuel out and measure how much you put in to full. Right now I believe that it is a 25 gallon tank but no proof…..yet....
Author:  longview [ Fri May 23, 2008 8:58 pm ]
Post subject: 
I just got word that my pump and wire harness should be here next week.
I will empty mine completely and measure the volume replaced.
Author:  tjkj2002 [ Fri May 23, 2008 9:25 pm ]
Post subject: 
Your tank is not perfectly symetrical,so what you figure to be a 1/4 tank is actually not,plus you need to take into acount the fuel level sensor and anything else that is in the tank will displace fluid thus upseting the true capacity again.
Author:  Bill.Barg [ Sat May 24, 2008 12:12 am ]
Post subject: 
From my experience, (which is identical to yours, so far except for the tab modification) is that the low fuel light comes on at somewhere near 2.4 gallons. In the manual it says that it is 1/8 of a tank , about 2.5 gallons. I believe you were looking at this volume in the bottom of your tank.

I have run 30 miles (1.4 gallons) past the low fuel light point, then am able to get 19.5 gallons back in.

So I believe that the tank is really 20.5 gallons, with 1 gallon wetting the bottom at its use limit.
Author:  Joe Romas [ Sat May 24, 2008 8:11 am ]
Post subject: 
I installed my pump as you did. Before and after dropping the tank I had one mark above empty. After driving 12 miles to fill it up it took 18.991 gallons and that would leave just over half a gallon. There did seem to be more in the tank then a gallon give or take as I was getting the tank in and out :? After the fill at 3/4 reading I had gone 150 miles and at 1/2 it was 280 miles. Then at about 1/4 and 360 miles I filled it up and it took 16.5 gallons. That equates to about 3 gallons left. These numbers are about what I had before the mod :lol: The FSM says 19.5 Nominal refill capacities are shown. I suspect our tanks including the filler neck are a little over what is claimed and we're just paying more attention to the guage after the mods :D
Author:  Turbo Tim [ Sat May 24, 2008 2:28 pm ]
Post subject: 
I haven’t calculated the area of the bottom of the tank as I don’t have time. My tank is actually taller than 12 inches and with the round corners, etc, all plays into the volume of the tank. It just seems to me before the mod that my gauge was below empty, light on, and there was over 3+ inches in the bottom of the tank. I know this is way more than 2 gallons of fuel. Now after mod it showed just above 1/8 tank and I believe that.
As to the actual amount of fuel that my unit holds, someday we will find out.

It would be nice that the next person that does this mod take the extra time and pour all the fuel out and then measure how much goes back in. (One could even do this before they put the sender unit back in and note it as a starting point when you go to fill up).

If I would have had an empty 5 gallon jug laying around I would have done this…
Author:  gmctd [ Sun May 25, 2008 2:12 am ]
Post subject: 
Both Jeep and Dodge sending units are identical resistance, the arms are identical, the float material seems identical - a kind soul sent me another Dodge module, which I promptly compared to the Jeep module - the arms hang the same angle, and travel the same distance - only the clocking is different, due to the indexing tab - all that is required is to compensate for the Dodge tab offset by bending the Dodge arm to match the Jeep arm such that it rests in the Jeep position in the tank - I don't recall doing that, but must have, considering the difference - I'm attempting to swap baskets, now - trying to determine best method of removing the tubing from the mounting plate

You guys should have seen this module: blacker'n the ace of spades - guy had obviously been recycling his used engine oil thru the fuel tank - tech that sent it to me said he couldn't figger out what had happened, why everything was black and grungy - owner said he didn't know, either :roll: - it cleaned up nicely, tho
Author:  Turbo Tim [ Sun May 25, 2008 12:11 pm ]
Post subject: 
I compared the resistance from stop-to-stop. Same. I compared the angles between the two, same. Length of the arm, float size, same. So the only difference that I can think of is the last ¼ tank calibration which I didn’t check.
I kept the old sender unit as it just pops out easily.
Right now I’m waiting to run it empty again so I can fill it up and see what the gauge says every ¼ tank mark. Then I will also know the total tank volume..
Author:  longview [ Mon Jul 07, 2008 10:29 am ]
Post subject: 
TurboTim wrote:
Whoever does the next lift pump install, Please dump all the fuel out and measure how much you put in to full. Right now I believe that it is a 25 gallon tank but no proof…..yet....


longview wrote:
I just got word that my pump and wire harness should be here next week.
I will empty mine completely and measure the volume replaced.


Well, I got my project done last week, and I put darn near exactly 23 gallons back in.

I put 2.75 gallons into the empty tank, then drove 12 miles to a B100 station and put in 20.7 gallons.
Since I should have used about .5 gallon getting to the station, this should be roughly 23 gallons to fill it full - including the filler tube.

(2.75 - 0.5 + 20.7 = 22.95)
Author:  JL Rockies [ Mon Jul 07, 2008 10:47 am ]
Post subject: 
Wonder why we have such a wide range of MPG's claimed by peeps on here?
Author:  BVCRD [ Mon Jul 07, 2008 12:14 pm ]
Post subject: 
JL Rockies wrote:
Wonder why we have such a wide range of MPG's claimed by peeps on here?






Driving styles, figure method ie.....evic vs paper and pen.
Author:  panda-52 [ Mon Jul 07, 2008 2:47 pm ]
Post subject: 
BVCRD wrote:
JL Rockies wrote:
Wonder why we have such a wide range of MPG's claimed by peeps on here?






Driving styles, figure method ie.....evic vs paper and pen.


Also foaming and impatience.
Author:  geordi [ Mon Jul 07, 2008 3:49 pm ]
Post subject: 
I wait until I have still fuel in the neck (double shot, no foam) and stop when I can't get any more in without spillage. To date, I have never run it empty OR gotten more than 19 gallons in it. YMMV.
Author:  longview [ Tue Jul 08, 2008 11:32 am ]
Post subject: 
Dont forget about:
F37 vs non-F37
SEGR or ORM
Lead foots vs hypermilers

There are lots of reasons for varying mileage.

I have been getting (calculated) 23-24 MPG at in-town speeds and 25-30 MPG at highway speeds lately. I have also been very aware of my driving habits for the past year or so and trying to conserve fuel.

However, the actual topic at hand was what is the real capacity of the fuel tank - not MPG.
As Turbo Tim hypothesized, the manual may state 20.5 gallons, but it is obviously much larger. Probably closer to 22.5 gal for just the tank plus a little extra in the filler tube.
Author:  Joe Romas [ Tue Jul 08, 2008 2:19 pm ]
Post subject: 
I've put 20.5 gallons in mine a couple of times but here's what's in the FSM for both gas and diesel on page 0-8 for the 06 kj's :D

19.5 U.S. Gallons (74L)*

*Nominal refill capacities are shown. A variation may be observed from vehicle to vehicle due to manufacturing
tolerance and refill procedure
Author:  longview [ Tue Jul 08, 2008 6:12 pm ]
Post subject: 
19.5, huh?

I hadn't noticed that before.
The owners manual says 20.5.
Either way, it is larger than either of those numbers.
My best guess (on my 06 anyway) is probably 22.5 gallons.
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