Hey all, I'm helping my friend do a WVO conversion on his 82 300SD this weekend, and we can't tell if there's a lift pump or not. I've searched the forums and the web and my guess is no. If there is one, can you describe where it is/provide a diagram? (Sorry. I feel like every time I post anything on here, it's a completely stupid question. My apologies, and thanks for your kindness and patience.)

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84 300D, greasified.

Yes there is a lift pump.

It is bolted to the injection pump. The primer pump screws into the lift pump, and the prefilter should be attached directly upstream (before) the lift pump.

awesome. thanks so much. you saved us.

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84 300D, greasified.

No problem,

And to quote Brian Carlton "Help is what we do here"

annemarie,

NO. The 300SD does not have a lift pump. It has a fuel pump that pressurizes the injection pump. A lift pump just "lifts" fuel, usually gasoline, to a carbureator bowl but the bowl is not pressurized. The float valve keeps the fuel in the bowl at a certain level. The gasoline is then pushed into the intake air stream by the venturi principle.

P E H

Its not called a lift pump? I've heard it called that here many a time. And by the way, if you bypass this thing on your veg side, like I did, you'll loose power at high rpms. Adding a low-psi fuel pump will solve this problem.

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Seth

1984 300D 225K
1985 300D Donor body
1985 300D Turbo 165K. Totaled. Donor Engine. It runs!!!
1980 300SD 311K My New Baby.
1979 BMW 633csi 62K+++? Dead odo

Alright, now I'm confused. On the 603, is the lift pump bolted directly to the injector pump? If so, then what comes directly after the pre-filter? What is it that the line after the pre-filter goes into?
Thanks,
Brad

The line after the primary filter goes into the fuel pump.

It will look like the item with the fuel lines going in/out of it on the lower left of this injection pump.

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reyn,

The reason the fuel pump (it is not a lift pump) is attached to the injection pump (IP) is that the same cam that drives the pumping elements of the IP drives the pumping element of the fuel pump.

The path of the fuel from the tank is fuel line, primary filter (inline filter), fuel pump, secondary filter (can filter), and IP. The 603 engine also has a fuel heater where the fuel is diverted thru the cylinder head to heat it. There is a themostat that regulates when fuel is diverted thru the head. When the fuel is cold it goes thru the cylinder head after the fuel pump. When the fuel is warm it goes directly from the fuel pump the to secondary filter.

P E H