Fuel tank(s) phantom

[jgh]

20050906

[NH model TN90F, orchard/vineyard machine with Iveco c.240 ci engine]

Does anyone have an idea why for the last several mos I cannot get my almost 14 gal diesel tank to go more than 5-7 gals before the gauge shows MT? I know there are 2 (connected) fuel tanks, one in front of the radiator (where the filler neck is) and the other below the cab floor (out of which I can see that lines run to and from the fuel pump).

An obvious gauge problem? Let me tell you about my onsite service bill around November 2004 for purging and restarting my blue wonder. I tried to test the gauge and ran out so solidly that serviceman Joe had to loosen the injector lines after I had vainly used the hand operated purge pump on the filter. So the gauge apparently works at the MT end. But get this-- though it appeared to take a long time to clear the final empty block compared to how fast it went down from half full--"half full" oddly is what it reads when I fill that front tank to the top. It has not "read" above half for about a year.

FYI, I had an overturn in October (see attached) and my machine went in to the dealer for check out. He charged me for over 10 hrs and a new battery that was not installed. Of course I wonder if they missed a pinched somethingoranother, etc. But since fuel is going in one tank and appears to be regularly coming out of the other one (going to the fuel pump), how can that be?

For now I just keep putting in 5 or so gals at a time, a pain while ranging out in the fields (totaling 80 acres in hay) cutting, baling, etc.

A weird one! Help me if you can, please /forums/images/graemlins/crazy.gif

And thanks!

Jim
Mt B on the R in VA [image]http://[/image]

 

[Soundguy]

Not specifically about your problem.. But... I know the fuel gauge in my NH7610s is not very accurate. It shows full when full.. and goes down as you use it.. but can show 1/4 tank when you are almost empty!!!

Soundguy

 

[Farwell]

My JD 2010 has a fuel gage that hasn't worked since I bought it so I keep a wooden dowel handy and do like the gas station fuel tank fillers do. I have been able to guess pretty well how long I have before the tank needs re-filled, yea right. I can't count the number of times I have to walk back to the barn to get a gas can. I don't have that far to walk but it is still a pain.
Farwell

 

[gmsssi]

My DK is listed as having a 15.3 gallon tank. When I get to MT it takes less than 10 gallons to fill. Heck of a reserve!.......but I haven't tested it yet... /forums/images/graemlins/smile.gif

 

[Junkman]

I don't know if this is going to help you, or confuse you more. The gauge is only able to accurately measure the amount of fuel based on a perfect rectangular container. If the tank (container) has dips and curves in it, then the gauge will not read accurately. The reason for this is the gauge can only sense depth of the liquid by the movement of the float. If it is wider at the top, then there will be more liquid at the top than there is at the bottom. Hence, it will stay on full for a longer period than when it reaches the mid point where the tank starts to get narrower. The the gauge will drop quickly. Sometimes, the tank gets so narrow at the bottom that the gauge never drops below a certain level. In these cases, the amount of fuel that is not measured is referred to as the reserve amount of fuel. This is a fancy term for "if you don't fill it now, we don't know how long it will be before you run out, but it is certain that you will run out.". In your case, there are two tanks, so it is assumed that one is always full, and the gauge only measures what is in the front tank. When the front tank runs out, you are supposed to fill it before the "reserve" or second tank runs out. The best method is to figure out how much fuel you use per hour and then determine how many hours a tank of fuel will run the tractor. This is what I have to do on my Kubota BX since the gauge on that is not very accurate. My 5 gallon tank will constantly take 4 gallons of fuel when the gauge reads 1/4 tank. When the gauge reads empty, it will take 4 1/2 gallons to fill it. Too close for comfort for me. I fill it when ever it reaches 1/4 tank.

 

[jgh]

20050906

Hey Junkman (did you see my HydroSeal post?),

I have a BX-2200 also, know what you mean.

The irony here is that the gauge used to work fine. Now it never reads above half. When apparently MT it only takes a little over 5 gals to fill to the brim of that upper front tank. As I noted, I have run out so I know to take MT seriously on the gauge, though my recollection was that the gauge was pegged on dead MT for an hour or so before I did run out. That does not seem like an abnormal reserve, though.

I am trying to recall how many gals it took to fill after I ran out last yeark, but I know it was not the NHolland manual listed capacity.

With the lines coming in and out of that lower tank, it has gotta be in the circuit, and since I add fuel to the upper front tank and get a move in the gauge by doing so, it is in it, too.

I'm beginning to suspect space aliens.

J
Mt B on the Rv in VA

 

[Osconda]

jgh,

You didn't exactly say this, but it sounds like the fuel gauge hasn't worked correctly since the roll-over. Is this true?

Also, I think what you're saying is that the fuel capacity has never changed, only the fuel gauge reading has.

Is it possible that you in fact have two fuel level sensors (one for each tank) that are somehow tied together to show you the total amount of fuel in both tanks with only one gauge? Seems like this is the only way it would work or the gauge would show completely empty when the top tank runs out or completely full until the front tank runs out. You might check your owner's manual and look at the electrical schematic and see if you have something like this. If so, then maybe a wire fell off of the front tank or shorted to something else in the roll-over.

Maybe in the rollover, some kind of float in the front tank got stuck. If you happen to find that you have wires coming from each tank(i.e. two sensors) you might try swapping where they connect and see what the gauge does when you refill the tank. If the front tank is out, and you swap the wires, then you shouldn't see any gauge movement till you fill up the lower tank.

Just more stuff to think about. /forums/images/graemlins/confused.gif /forums/images/graemlins/confused.gif
Good luck on solving this one

 

[dixiedrifter]

Had the same problem as yours, could only fill up one tank at at time.

Turns out a dirt dobber got into the breather line of the other fuel tank creating a vacuum lock!

Each tank should have a breather line coming out of it. Check to make sure they are not stopped up.

 

[jgh]

20050923

Did some testing today with former NH dealer service mgr helping: with the front (upper) tank almost full, it read about 13 ohms on the sender with wires disconnected. On the rear (lower) tank, which should be full while there is anything in the upper tank, it reads 150 ohms. HB tells me that lower readings mean less fuel in the tank, so the rear/lower reading is obvioulsy wrong! I'm writing the NH service rep for help (dealer did not have a solution). It may be the sending unit in that tank, but that means I have to run it out to prove that only the gauge is wrong.

I have not yet found a clogged tube.

If anything new comes to mind, please let me know!

Thanks!

Jim

 

[HammerFour]

Ok, if lower ohm reading means less fuel....

Lower tank reads 150 ohms when full. That makes sense compared to the following...

Upper tank reads 13 ohms when full. So Upper tank sensor is stuck at the 'empty' position or something....If it is the same sensor as the lower tank, it should read aprox 150 ohms when full.

So the gauge reads 300 ohms of resistance across both sensors = full tanks.

What you are seeing as the half tank on the gauge does make sense here, one tank is showing full on the sensor, the other is showing empty.

That scenario would make the gauge read empty when they are both empty, the gauge would start dropping as the bottom tank empties out as it has a working sensor along with the upper tank being already empty which is what it's defective sensor has been showing anyhow.

The sensor in the upper tank needs to be checked imo, maybe remove it and check to see if the float is stuck/defective or something.

I don't have any ideas about your earlier post about the tanks not holding as much as they used to tho.