CDT LP Fuel Supply Flow
 

Dropped the fuel tank on my scrapper today and had a look at the way the fuel pipework runs.

This is a sketch of how it is all plumbed in:

https://i.imgur.com/3nVcagV.jpg

Looking at the way it is piped, when the fuel is cold and the thermostat is shut this is the flow path of the fuel:

https://i.imgur.com/WeQtrGc.jpg

So the fuel recirculates in the LP circuit until it has warmed up with the losses to the engine being topped up by the ITP.

When the fuel returning down the spill line is hot the flow path changes:

https://i.imgur.com/e8PkubJ.jpg

In practice, once the car has warmed up, it's likely that varying amounts of fuel will pass down both paths depending on the conditions to regulate the fuel temperature in the circuit to 76C, and a small amount of fuel may go through the restrictor valve to ensure that the return lines don't over pressurise.





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Nearly 12 months on and i have only just read this, excellent post thank you for taking the time to do this Mike :bowdown: Arctic

This is a brilliant diagram. One question, if you have the single in tank pump (As I do) where it says "to UBP" would the line just go straight to the fuel filter or is it a completely different system?
Regards DaDragon

From a Rover technical sheet :

http://i517.photobucket.com/albums/u...g?t=1420979642

http://i517.photobucket.com/albums/u...g?t=1420980029

No problem Steve. I was going to do the same for the tank internal pipework but thanks to brgcdti's diagram it doesn't look like that is necessary.

Mrs Noc's Auto 75 has the single LP pump set up dadragon, but so far nothing has gone wrong with it, so I have yet to have it apart.

I'm sure Marinabrian could shed some light on it though because he has had some issues with his.

Comparing this diagram with the one in Rave suggests one of them is incorrect. The write-up I put together here: http://www.the75andztclub.co.uk/foru...d.php?t=108535 shows the two static (venturi) pumps being powered by the HP return from the front end. The latest diagram shows them powered directly from the ITP. Considering the diesel's pumping needs on the LP side, one wonders whether the ITP really needs all its flow going to the engine bay? But one might then ask, is there enough HP back flow from the engine bay to power two in-tank venturis?

It's not unknown for Rave to be incorrect of course. But there is clearly a discrepancy here that only a physical examination of the tank will resolve. I note there's no pressure regulator in the tank on the later drawing.

TC

EDIT: Brgcdti, please could you post the link to the document cited?

T-Cut, I read your link, http://www.the75andztclub.co.uk/foru...d.php?t=108535 also very interesting but it still doesn't clarify if the fuel line system on the single pump is different from the duel pump. You do mention they can't be changed to a single pump set up (which is a shame for those who wish to) but still no diagram of the single pump fuel plumbing set up. It's only for my own edification you understand, I don't have any problems (touch wood!!) it's just interesting reading!! :D
Regards DaDragon

I am bumping up this excellent thread, as I am sure it will help quite a few members ;)

Any chance these pictures could be rehosted please?

Thanks :)

Mike reposted all three of them in a new thread, here -
https://the75andztclub.co.uk/forum/s...61#post2525361

It would have been better had Mike simply deleted the photobucket links and pasted his pictures in the existing post - Mike?