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MK Wagon, and an SD33T in pieces...
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Discussion Starter · #1 ·
Hey all, I'm just looking for some info about the SD33T's stock mechanical lift pump, TD owners input would also be appreciated as I'd say the specs would be about the same.

As I've mentioned in a few threads before, my SD33T has had the mechanical lift pump removed from the injector pump, and I'm running a holley blue fuel pump and pressure regulator to feed fuel to the system.

I just was wondering what kind of pressure the mechanical lift pump would usually supply to the injector pump, so I know what pressure to set the regulator to?

Usually when you've got an electric fuel pump, you've also got the mechanical one as well, so you don't need to run much pressure, but since I don't have the mechanical one, I need to run the same or more pressure than it would produce.
Thanks
 

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Registered
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248 Posts
Hey all, I'm just looking for some info about the SD33T's stock mechanical lift pump, TD owners input would also be appreciated as I'd say the specs would be about the same.

As I've mentioned in a few threads before, my SD33T has had the mechanical lift pump removed from the injector pump, and I'm running a holley blue fuel pump and pressure regulator to feed fuel to the system.

I just was wondering what kind of pressure the mechanical lift pump would usually supply to the injector pump, so I know what pressure to set the regulator to?

Usually when you've got an electric fuel pump, you've also got the mechanical one as well, so you don't need to run much pressure, but since I don't have the mechanical one, I need to run the same or more pressure than it would produce.
Thanks
The lift pump works on vaccum from the injector pump. Its only pressurised manually when bleeding the fuel lines. 3-5PSI on an electric pump should be fine.
 

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Registered
MK Wagon, and an SD33T in pieces...
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647 Posts
Discussion Starter · #3 ·
The lift pump works on vaccum from the injector pump. Its only pressurised manually when bleeding the fuel lines. 3-5PSI on an electric pump should be fine.
Oh ok, I was thinking it might have been driven by the engine indirectly through the pump and pressurized the fuel similar to a more modern diesel or petrol, that's good to know though. I'm currently running slightly more than 5psi, and when on the dyno I watched the pressure regulator gauge under the bonnet, which didn't drop in pressure through the rev range so it must be able to feed it alright.
I guess if it was able to feed the prev owner's 351 it'll feed the comparatively small SD easily enough.
 

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1989 GQ TD42 wagon
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Oh ok, I was thinking it might have been driven by the engine indirectly through the pump and pressurized the fuel similar to a more modern diesel or petrol, that's good to know though. I'm currently running slightly more than 5psi, and when on the dyno I watched the pressure regulator gauge under the bonnet, which didn't drop in pressure through the rev range so it must be able to feed it alright.
I guess if it was able to feed the prev owner's 351 it'll feed the comparatively small SD easily enough.
Diesels have a fairly high fuel flow rate, as the fuel is used for lubrication and cooling of the injector pump. Most of it is returned to the tank.
 
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