The Lotus Grand Tourers

My 1990 SE has two take off pipes on each carb just by the inlet manifold. The rubber pipes that attaches to these are totally shot. Where can I find them and what are they called!

This might help for names based on function. LB might have/suggest new sources?

That is an excellent diagram to see, as the system on my car is all apart!

Zaphod wrote: ↑

Sat Oct 02, 2021 10:28

That is an excellent diagram to see, as the system on my car is all apart!

Yeah Bryan on here did the original diagram in order to get an overview of the system and I added the functional notes taken directly from the textual notes within the Service Notes (no charts in SN).

I've also producd a colour-coded diagnoistic chart for the Vacuum Engine Management system (again, only explained in text within Service Notes) in PDF form which you use in conjunction with the overview diagram.

Clink link here to download the pdf. It's A3 format! So you need a big screen, or an A3 printer, or use the magnify function.
https://onedrive.live.com/embed?cid=752 ... ling="no">

This is a jpg of the chart. Resolution won't be a s good as the pdf above.


You won't need the chart until you've put it back together - it's more useful for fault diagnosis.

This topic is now a sticky. Will copy it across to Technical Articles as well. Great work Peter (and originally Bryan).

Cheers Richard

Glad you found the diagram helpful! I replaced the "F-Pipes" (the moulded pipes that connect to each carb) on mine because the originals were split, but the replacement ones (which were some ridiculous price) also split within a couple of years. In the end, I made my own using 4mm ID silicone tubing, which I also used to replace all the other slightly ripe engine management pipework, plus some interconnecting T-pieces, which are available from Halfords or motor factors:

https://www.ebay.co.uk/itm/401073216147

https://www.ebay.co.uk/itm/114603709270

The silicone tubing seems to last indefinitely too.

Lotus-e-Clan wrote: ↑

Fri Oct 01, 2021 22:17

This might help for names based on function. LB might have/suggest new sources?

Thanks for the wonderful diagram! On item 9, I am struggling to see the correct orientation. Which pipe goes to the connection with the pin hole?
Thanks

Can't recall seeing a pinhole, but I haven't had the airbox vacuum pipes off for years.

When cold, the air box sensor should allow vacuum to reach / communicate with the diverter valve in the air intake stub (open circuit when cold). When warm, no vacuum should reach the diverter valve (closed circuit when warm).

The valve is situated under the airbox, so copy the pipe connections when looking up under the box.

Thanks Peter.
The two stubs on the actuated valve are different. One is ‘full bore’, the other is reduced to a pinhole. I’ve connected them with the pipes crossed as shown in your diagram. We will see what happens. (Probably nothing, as they look to have been disconnected for ‘some time’ )
Cheers
Nigel

Jnh wrote: ↑

Mon May 09, 2022 19:25

Thanks Peter.
The two stubs on the actuated valve are different. One is ‘full bore’, the other is reduced to a pinhole. I’ve connected them with the pipes crossed as shown in your diagram. We will see what happens. (Probably nothing, as they look to have been disconnected for ‘some time’ )
Cheers
Nigel

Ha! I've never looked down the bore. Please report back, so we all know what's what on that!

Worth updating the graphic when we know.

I will take photos.

Maybe some people are aware, but as this has become a "Sticky" in the Technical Articles, there are now two versions with this title, the other under "engine and Gearbox".
Since Oct 21 when they diverged, both contain different, but relevant and useful information.

I only realised, because I wanted to add a photo and for whatever reason, the version under "Technical", doesn't offer me the Formatting banner just above the box I'm typing in.

I'll copy my scribbling across into this version.

Tony