TWO tanks, and I ran out of diesel with 20 gallons remaining

diesel
gas-tanks
isuzu

#1

I’m an artist, so my "pickup truck’ is actually a large Isuzu Cabover called an FTR; you’ve all seem 'em, they’re nearly all white and most have boxes on the back.



Anyway, I have two 50 gallon tanks, but last week started up a slight hill and the engine ran out of Diesel!!! (this is a bad thing for those who know diesel engines.



Anyway, I was SHOCKED to discover that when I got towed and restarted that I still had 20 gallons of fuel!!!



What happened?


#2

You were running on the empty tank…


#3

Thanks Caddyman,

I forgot one piece of information, it pulls from both tanks simultaneously… there’s no switch to go from one to another.


#4

The only thing that comes to mind is, if it pulls from both tanks simultaneously then one tank had less fuel than the other so the fuel pump ended up pulling air from the empty tank. Could be the fuel line that connects both tank has a problem


#5

How old is your truck? It could be the fuel lines from one tank to the other have a problem, kinked, clogged, or the pick up screen is clogged with dirt on one tank.

Perhaps parking on a steep hill could affect the balance of fuel in the tanks. Since this can recur you need to troubleshoot the problem. Some fuel tanks are complicated and involve multiple fuel pumps.


#6

It’s a 1999 Isuzu FTR.

I did think of one POSSIBLE cause:
I believe the last time I got fuel, I only filled one tank (50 gallons of diesel only meant I couldn’t eat for a week instead of not eating for 2 weeks with 100 gallons).

I always presumed the tanks would level themselves out.

Is it possible that if one is empty and one not, it could have just sucked in air as I drove up the hill? (I would have thought the designers would have taken this into account.)

Thanks,

James


#7

If you have a 99, maybe this doesn’t apply to yours.

ISUZU FTR 1997 Safety Report #SB9902C003

ISUZU FTR 1997 technical service bulletin was issued Sept 01, 1999.ISUZU FTR 1997 had a failed FUEL SYSTEM, OTHER . CERTAIN VEHICLES EQUIPPED WITH 50 GALLON DUAL FUEL TANKS MAY EXHIBIT INACCURATE FUEL GAUGE READINGS. THE INACCURATE READING MAY RESULT IN RUNNING OUT OF FUEL WHEN THE GAUGE INDICATES THAT THE TANKS ARE 1/4 TO 1/2 FULL.


#8

Running out and having 20 gallons are mutualy exclusive terms,which one is it,you ran out or you had 20 gallons?


#9

The ENGINE ran out of fuel.

Apparently the TANKS (or tank) still had 20 gallons available since I only added 80 gallons to them.


#10

How long does it usualy take the tanks to go through 20 gallons?


#11

I get around 5mpg, so I should have had 100 miles left. The gage was reading near empty, but I’ve had the truck for 7 years and usually that’s PLENTY (most of my driving is just around the area).


#12

How do you know you have 50 gallon tanks?

Five miles per gallon? Is that normal for this type of vehicle?


#13

Over-the-road semi-tractors pulling 80,000 pounds get 10 or 12 mpg…8 worst case…$400 fill-ups makes it tough to make a living with that rig…


#14

Actually, on the highway I can get 8, but around town it sucks fuel, and since I have a boom on this truck (see picture above), there are times I’m using fuel and not driving for hours at a time and that helps me average the 5mpg.

But the Mileage is never great. I would have hoped for more for a 20,000 lb with a 6 cylinder. Oh well. Back to the FUEL question…


#15

A couple of possibilities.

One, that the ‘equalizer’ that is supposed to keep a balance of fuel in both tanks is clogged or kinked, as mentioned before. Has this theory been checked yet?

Two, the fuel pick-up tube is in an awkward location(s) in the tanks, allowing for fuel to move away from the pick-up tube when the truck is inclined. I have this problem with my 2000 Ford Explorer. If I’m down to 5 gallons in the 21 gallon tank. I have to remember to park nose up. If I park nose down, the fuel flows away from the fuel pump, and the truck will not start. It is located too far back in the tank.


#16

10 to 12 MPG in an 80,000 lb. tractor trailer is unheard of. Most average between 5 & 7 MPG, and even the latest hi-tech, low drag examples are hard pressed to top 8 MPG. I get 5.6 MPG loaded, and close to 7 MPG empty with an older Cat with mechanical injection.