My 76 300D 114 has dual fuel tanks . I filled the tank in the trunk and then ran out of fuel, I cant find a switch or a lever to change the tanks over. Is it automatic or do I need to manually switch tanks??

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Lower your carbon footprint. Burn Biodiesel, Buy Local,

1976 300D 115 high miles, broken odometer (sloooow)
1979 300SD 116 155,000 mi. (fast)

How do you know it's dual tanks? Just curious.

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1983 Mercedes-Benz 240D
Automatic, A/C, Power Sunroof, Power Right Side Mirror
231K Miles FOR SALE MAKE OFFER

I had an 81 300D with two tanks. The second was an after market that held 21gals. They were connected together with a large (1-1.5") hose from underneath. That way there was no switch and the fuel gauge worked.

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81 300D Turbo 190K sold
83 300sd 319K best $500 I ever spent-daily driverw/ 2 tank WVO set up

the second tank is in the trunk, it had 10 gallons of diesel in it but I still ran out of fuel,

__________________
Lower your carbon footprint. Burn Biodiesel, Buy Local,

1976 300D 115 high miles, broken odometer (sloooow)
1979 300SD 116 155,000 mi. (fast)

That's aftermarket. If the car didn't come with any documentation on that modification, you'll just have to keep looking until you see how (if) the auxiliary tank is hooked up.

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Whoever said there's nothing more expensive than a cheap Mercedes never had a cheap Jaguar.

83 300D Turbo with manual conversion, early W126 vented front rotors and H4 headlights 400,xxx miles
08 Suzuki GSX-R600 M4 Slip-on 22,xxx miles
88 Jaguar XJS V12 94,xxx miles. Work in progress.