Originally Posted by silver_eye
Heard from the dealership yesterday - they were able to get the truck to stall. They found that the fuel filter cap was cracked, and that the truck has a large aftermarket fuel tank. They think whoever installed the large tank used the fuel fender (? part that sucks up the fuel) from the original tank, and that this isn't long enough, and so when it gets below 1/4 tank, it sucks air. Their recommendation is to go back to a stock tank. The fuel gage and heads-up display would then read properly, and they can replace the fuel fender if it has become damaged.
Alternatively, the service writer said they could pull the tank and see if anything is damaged, and if not, just be careful to keep it well above 1/4 tank.
I know nothing whatsoever about diesel engines (except what I'm learning from this site - thanks!), but this all doesn't quite make sense to me. The fuel gage read just below 1/2 tank when the stall first happened. I am pretty sure I've run it to just above 1/4 tank before without problems. I generally fuel it before it gets to 1/4 tank. And if I recall correctly, when I test drove it at the dealers, they had to run it to a gas station so I'd have enough fuel for a test drive. It ran fine.
It also doesn't make sense that installation of a large fuel tank would require the owner to guess as to the amount of fuel left, and keep the tank mostly full to avoid stalling. What's the point of a large tank then?
Any insights will be most appreciated -
If it is a "Transfer Flow" fuel tank it uses the stock sender and pick up, if it is an "Aerotank" then the stock sender has to be cut and lengthend. I bet that the tank works properly and was installed by the previous owner who put 50K miles on the truck in 18 months.
The cracked fuel filter cap can allow air into the fuel system causing the truck to run rough and lean.
The black smoke you were getting is from a rich mixture or the EGR valve is sticking or one of the other sensors is acting up.
The stalling could be from a high pressure oil problem. Could be a leaking fitting or a defective check valve. The defective check valves can be difficult to diagnose.
If it was me i would take it to a different dealer that has a better trained and qualified diesel tech. Telling you to remove the A/M fuel tank and go back to stock is pretty lame.