For 2 tank VO system schematics see link below, click on install manual and then go to pages 16 for a 2 valve system and page 17 for a 3 valve (controlled loop system) This may clarifie some things for some people. This is thanks to frybrid.

Frybrid Vegetable Oil Fuel Systems -- Manuals

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2005 e320 cdi (132,000)
2005 Jeep CRD diesel--2.8L (138,000 miles) wrecked, insurance took
1993 Mercedes benz 300D 2.5 Turbo Frybrid powered. (336,000 miles) wrecked and sold as parts car
1990 Mercedes benz 300D 2.5 Turbo (170,000 miles) wrecked and sold as parts car

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