Originally Posted by genscripter
Does anyone have a picture of where aux fuel ports are on a 7.3 IDI?
The IDI is a completely different animal than the conversion described here. The PSD engine uses high-pressure oil to produce 'injection pressure' and has a fuel rail that goes from one end of the head to the other to supply ~60psi of fuel to the injectors. The '99-up engines only use one end of the fuel rail to supply fuel to the injectors - we often use the other end for WVO and purging...
The good news is, its likely cheaper to do a good 2-tank conversion on your IDI than it is on our PSD's. I just did a conversion on a 2005 med. duty Isuzu truck and used greasecar valves. There is nothing else I would buy from that company, but the Hydraforce SV98 valves are good for this application and GC has had a manifold built that neatly houses (2) valves and is fairly easy to mount.
What you DON'T wanna do is use a typical 6-way switching valve that is commonly used to switch tanks on a truck with (2) fuel tanks. You need to switch the supply back to diesel and continue returning to the VO tank until all of the VO is out of the engine - then switch the return to the diesel tank before ya shut down. If you switch both at the same time, you are slowly contaminating the diesel tank with WVO. Besides, if you manage to get the VO as hot as it needs to be (>160*) - the motor-driven pollak valve won't last long anyway...
What you DO wanna do is use a heated fuel pick-up in an aluminum tank, heated fuel lines (TIH - 3/8" aluminum tubing inside 3/4" heater hose) and at least a 16plate flat-plate heat exchanger to make sure the fuel is HOT. Adding a 3rd 3-way valve to the 'return' line and 'looping' the return fuel back to the supply valve while running on VO will add a considerable amount of heat to the VO and reduce the strain on the lift pump.
The system I just installed on the Isuzu has a simple on/off switch. When ON, both valves switch to VO - when switched OFF, the supply switches back to diesel and a timer relay was used to keep the return valve open for an additional 30-40 secs. The driver watches the coolant temp on dash and switches at 'operating temp', then turns the switch off when he returns to the facility. When I get back out there, we'll install a temp switch that will automatically switch over to VO when coolant temp gets high enough and maybe even incorporate a DIY 'turbo timer' to automatically trigger the purge cycle at shutdown - for a fully automated VO system.