Truck won't run past 1/2 tank

[llotton]

I have a friend with a 2004 1/2 truck he is the original owner. When the truck gets below 1/2 tank it all but shuts down. He replaced the in-tank pump and it is better but still will hardly run if below 1/2 tank. If the tank is filled the truck runs great. Any ideas?

 

[cerberusiam]

Is the fuel gauge really correct? In-tank pump should not have a delivery problem at half tank.



He has changed fuel filter to rule that out, right?



Vent possibly plugged and causing a vaccuum?



Couple of things to check, good luck.

 

[zzman]

what if the draw tube has a hole in it? half way up maybe.

Is that even possible?

 

[cerberusiam]

Its not a draw tube with the intank pump, its a push tube and that should no matter the fuel level.

 

[llotton]

Thanks Cerb. as for the filter Yes The guage believe so, and as for the vent will check. Thanks again.

 

[llotton]

Just an update and request for thoughts on the issue. Fuel level at about 3/4 tank (verified by dropping the tank) truck runs great. With clear line from the tank to the hp pump nothing but fuel is observed. Lower the fuel level to about 1`/2 tank truck starts, then goes right to running rough, stumbling and air can be seen in the clear tube. What could be causing this? the intank unit is new and is well into the fuel level (approx. 1/2 tank) And forgot to say the Vents are clear. Any help appreciated.

 

[cerberusiam]

Was the fuel cannister replaced when the pump was replaced with the in-tank?



The screen on the cannister is clear and the return fuel is routed back into the cannister?



It really sounds like you have cavitation at the point the fuel level gets so low which would mean the pump is just sucking the cannister dry.

 

[llotton]

final word. The new pump acted just like the old pump. **** poor design. Owner is installing an "Air Dog" . Special thanks to Andy Redmond and all who helped.