Hi:

Great forum.

Recently purchased a 1991 F250 with 7.3 IDI diesel, and I have no experience with diesels. Please execue me when I use the incorrect terminology.

I'm trying to identify the fuel return line. I've located the fuel line into the fuel filter and to the injector pump from the filter. There is a hose that goes from the fuel filter holder to the passenger side fuel rail and another hose that goes from the driver's side fuel rail to the injector pump. Are these fuel return lines? If so, why does one go to the filter and the other to the injector pump.

I took pictures but was not sucessful in attaching them.

Thanks

 

Yes that is the return, If you look at the back of the engine you will see that they come off the last injector on each bank to a T and then back to the fuel tank.
I believe they come off the filter and IP so they will bleed off any air that gets into the system.

 

The one connected to #1 injector has a check valve on the filter header .... it allows air to exit the header so as not to go to the IP. Air should not go from the #1 return line to filter header. The IP and injector return lines are for the injector/IP excess/cooling fuel to return to the tank selected.

Our fuel system is a closed free flowing system..... ie it never stops.....just continually gets sucked from the tank, pumped through the filter..... through the IP and returns to the tank. The IP removes what it needs on the way by.

Any air leaks in the closed system allow the fuel to drain off the highest points........the filter and IP. This causes stalling after starts.......due to lack of fuel in/to the IP until it is refilled again.

visit........
http://www.intellidog.com/dieselmann/idi.htm read all about 7.3 fuel system air leak points and GP systems.......

 

Thanks for the replies. I want to use Diesel Purge to attempt to clean my injectors in a similar manner in the link below. How would one go about it?

Thanks.

http://forums.tdiclub.com/showthread.php?t=87948

 

Normally we would do it when changing fuel filter, just fill the filter before installing it. Start the engine and it will clean the IP and injectors as it flows through and back to the tank for mixing with fuel to be pumped back to the filter and IP etc.... as your driving until tank is ready for refill. If you want a higher concentration in the fuel, have less fuel or more additive.

Most members use Power Service, Stanadyne, Hayes etc products to clean IP and injectors..... on a continual basis..... a little with every fill. Lubrication is a must now with new fuels, the above products offer that too not just cleaning.