Engine/Transmission (1998.5 - 2002) unused fuel returned to tank?

[Whitmore]

OK, I know that there is extra fuel circulated thru the vp44 for cooling and lubricity and I also know that there is some extra fuel returned from the injectors for cooling that is collected thru a galley inside the head and discharged from the back of the motor, it is my understanding that there is a check valve some where in this return line I think its on the vp side before the "T" of the injector discharge.



I have had for some time now my main supply of fuel to the lift pump comming from the bottom of my aux tank in the bed of the truck , this gives the l/p a possitive pressure and it no longer has to suck fuel from the oem tank, this has been great.



Here is my question... ... ... ... ... . I also have the combined return line from the motor going into the top of my aux tank that is higher than the discharge of the motor, so I have eliminated gravity flow on the return line and all returned fuel has to be pumped back to the tank, is this hurting anything



cheers, Kevin

 

[Steve Campbell]

IMHO.....

No!!!



I think you would have to be above 6-8 lbs of back pressure to even start to be concerned.

 

[TXRam]

Steve's right ...

This will not cause any problem.

 

[15w40]

From the Cummins “Troubleshooting and Repair Manual ISB“

Bulletin No. 366193-01

Printed 2/99:



Maximum Fuel Inlet Restriction to Lift Pump: 6 in Hg

Maximum Fuel Pressure at Fuel Filter Outlet (Engine Cranking): 4 to 8 psi

Minimum Fuel Pressure at Fuel Filter Inlet (Engine Running): 8 to 17 psi

Maximum Pressure Drop Across Fuel Filter: 5 psi

Fuel Drain Line Maximum Restriction: 10 psi

Fuel Inlet Maximum Temperature: 165*F

 

[illflem]

So at 10 psi max restriction the top of the fuel level in your tank would have to be about 23 feet above the engine. Think you're probably safe Kevin!

 

[Whitmore]

Was kinda curious and like always the TDR buddies have come thru again



cheers, Kevin