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[holliday0]

Im just about done with my WVO conversion on a 96 PSD. I started out buying a Greasecar kit and wanted to offer my suggestions while asking for some advice. The Greasecar kit works okay and is much cheaper. That being said, you get what you pay for and “okay” doesn’t win the prize. After buying GreaseCar, I put a lot of extra money back into the kit upgrading parts. I wish I would have gone with the Veggiestroke system as it seems like that is what Im getting closer to with every part I buy. However, if you already made the leap and bought something, or inherited a different system, its awfully nice to make it work rather than throw more money at the truck. All that aside, the Greasecar system seems to give you the basics to get it converted and you can build on it from there if you are a gearhead and want to tinker.

I have a 40 gallon insulated tank in the bed with an in-tank coolant heat exchanger. Tank is drilled and tapped with fuel level sender and temp sensor. Hose in hose heating to a coolant heated veg filter (70 micron Webb). Then flows to a secondary filter (10 micron Racor with heated element). Im happy with my conversion, but one part of the Greasecar setup still bothers me. This is where I was hoping to get some help from you folks. As I read the forums, I see about half the people complaining about failed lift pumps and half saying it’s fine. Let me say from the outset, that I am not a mechanic. The following is a possible solution I came up with after reading tons of forums on PSD conversions and tech manuals. I wanted to post in a forum with folks that really knew their PSDs and could correct me on all my wrong assumptions. Please read and let me know where Im wrong:

It would seem to me that the best place to inject WVO into the system would be at the bottom hose of the mechanical tandem pump (after the stock diesel filter, prior to the 40 psi mechanical pump).

The 94.5 – 97 DIT powerstroke stock fuel system draws diesel from the tank(s) directly to the driver’s side upper port on the mechanical lift pump. Diesel is then directed from the passenger side upper port of the mechanical lift pump to the stock diesel filter housing at a pressure of (roughly) 4 – 6 psi. Diesel fuel return flow is regulated through this canister with the pressure regulator valve integrated to the side of the filter housing. Diesel fuel is drawn from the bottom port of the stock fuel filter housing to the bottom port of the mechanical fuel pump. At this point, the fuel pump increases pressure to roughly 40 psi and supplies the cast fuel rails with diesel. Excess diesel fuel from the rails returns to the diesel filter.

The greasecar system changes the fuel routing to avoid cross contamination of diesel with WVO / SVO. The new routing relies on the mechanical lift pump to draw diesel THROUGH the stock diesel filter and into the driver’s side upper port of the mechanical lift pump. My first concern is that, at 4-6 psi, the drop in pressure across the filter membrane (especially once it gets dirty) will not only strain the mechanical lift pump, but starve the diesel supply. Once the diesel flow arrives at the 4 -6 psi inlet of the mechanical lift pump, it is immediately directed to the 40 psi inlet (bottom hose of the mechanical pump). It would seem to me that any diesel fuel starvation problems would only increase at this point. Could be very wrong though.

Finally, and this is my big problem, the grease car system has already placed a small amount of increased strain on the factory lift pump by requiring it to draw diesel through the stock filter rather than unabated from the diesel tank. BUT, when switching over to grease, the mechanical lift pump must now pull grease from it’s respective tank – through whatever menagerie of filters the builder has put in place – to the driver’s side upper port of the mechanical lift pump. Again, from this point, the grease / fuel is directly sent from the passenger side mechanical lift pump exit to the lower 40 psi mechanical fuel pump port. I just see this as a large amount of strain on the mechanical lift pump and it COULD explain the common failure of the lift pumps after installation of the grease conversion.

Arguably, the best systems out there seem to deal away with the mechanical lift pump all together and put two fuel pumps (one for each fuel source) flowing to pressure regulators. Essentially, creating the fuel system on the 99 and up Powerstrokes. Of course, all it takes is money. Grease car’s routing of the fuel (particularly the diesel fuel) in their system avoids contamination of the diesel fuel and also allows for an easy purging by utilizing a common purge line (off the back of the pressure regulator).

Here is my question: Why wouldn’t someone leave the stock diesel flow alone. This alleviates the undo strain on the mechanical lift pump by drawing through the filter. Insert the solenoid / T / check valves (whatever method you want to use) in the lower fuel port on the mechanical lift pump between the diesel filter housing and the pump. This is the supply line to the 40 psi fuel pump. When the solenoid is open, diesel flow is normal and drawn by the mechanical lift pump, to the filter, to the bottom port of the pump. Diesel bypass is handled normally, through the pressure regulator on the filter housing. Injector bypass would need to be spliced into the common supply line feeding the lower port on the mechanical fuel pump . This eliminates contamination of the stock diesel filter when fueling with grease.

The other side of the solenoid or valving (that was spliced in as above) would be fed by the grease system. This would mean the normal heated lines, grease only devoted heated filters, heated tank, etc. Additionally, a small supply pump which is pressure regulated to 4-6 psi would provide the lift to the mechanical fuel pump. Bypass off the grease pressure regulator would return to tank or filter as the user sees fit. When burning grease, the bypass off of the injector rails would be looped around and fed into the bottom port of the mechanical fuel pump as described above.

The only hurdle left (that I can see) would be purging. My suggestion would be to use the second greasecar solenoid in the diesel return line. When purging, diesel would be redirected from the diesel tank over to the grease supply line. A check valve prevents grease from entering this purge line when fueling with grease.