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Has anyone tried the new Dansk repro fuel tank?
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barnwerks  



Joined: 28 Oct 2022
Posts: 35
Location: Northeast and southeast US
PostPosted: Fri Dec 27, 2024 8:12 am    Post subject: Reply with quote
[quote="Raize"]
Kenodog wrote:




It really makes me wonder how we had the early 924 with no in-tank pump, then the later 924 with an in-tank pump, then the 944 with again no in-tank pump?

What changed on the 944 that it could operate with only an external pump? Why did the 924 get an in-tank one in the first place?


I have come to understand that the in-tank pump was (occasionally) required to eliminate the possibility of cavitation on the suction side of the main pump. This could happen at low fuel (tank) level along with high altitude. This is perhaps something that was learned with the early 924 and the in-tank feed pump was the resolve. The same design exists on the early 928's, interestingly, the 928's were all wired for the in-tank pump but not all cars received the pump, seemingly based on global destination.

The difference in the 924S, 944 and later 928's that eliminates the need for the in-tank pump corresponds with the switch from the CIS K jet to Motronic or L jet fuel injection systems which require much less fuel delivery pressure.
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Raize  



Joined: 18 Sep 2013
Posts: 281
Location: Scotland
PostPosted: Sun Jan 19, 2025 8:51 pm    Post subject: Reply with quote
I guess one other issue with the in-tank pump is if it stops working, you end up with a pretty big restriction in front of the main pump.

I found data on the main pump that I'm using that says it's rated to 500mm of suction head, it's a Pierburg E3T internal gearotor pump, not sure if the Bosch roller cell pumps would be better or worse at that application.
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