Lotus Elan and Lotus Elan Plus 2 Forums

elanner wrote:Simon,

Ah, that's interesting, thanks.

I must be the only person who actually likes the starter circuit. The sheer simplicity (crudeness?) of the design appeals to me and I use it whenever cold starting. I find it very effective and don't have to bother futzing around with the accelerator pump.

That said, it's an area of the Weber that can go wrong and most people never use it, so I can understand why it gets blanked off. Perhaps I should do it temporarily to prove my leaking theory....

Nick

fatboyoz wrote:Hi and Happy New Year,
I had a similar problem that eventually started leaving a puddle of fuel under the engine. It used to manifest itself a few minutes after shutting down the engine after having driven the car.
The following is what was suggested to me. I followed this procedure which cured the leak.
Regards,
Colin.


Throttle lever housing cover plate dribbles:

? The throttle lever housing cover plate is between the two barrels and is fixed with two countersunk screws. (Figure 1 ? item 80)
a) Remove the screws and plate. A full sealing gasket should be in place. Remove it and check if the chamber is wet with fuel or shows signs of this.
b) Fuel can enter the chamber via the pump rod hole or the return spring hole. Yes I realise this should not be the case BUT do you have ANY clearance in the butterfly shaft bearing on either side of the chamber. Of course you do even if it?s only small.
c) When you are pulling 5000 to 6000 + rpm and lift off the throttle you can appreciate many inches of vacuum generated must suck from anywhere it can. Herein lies our problem. Fuel is sloshing around in our float bowl through corners and clearances around pump rod and throttle return spring hole are considerable. The vacuum pulls fuel into the chamber but there it just builds up to gradually dribble over our distributor or hot exhaust as the case may be.

Solution to throttle lever housing cover plate dribbles -

Drill a 1.5 mm ?breather hole? in the cover plate and match drill the gasket. The hole should be level with the top screw and half way to the edge to miss the housing cast edges.
The small hole stops the effect of the vacuum but also keeps the dirt out of the throttle lever chamber. Screw the plate back on for dry, dribble free motoring.

This really is an incredibly simple fix for a rather obscure problem. It took a lot of reasoning and close inspection to analyse what was actually happening but investigation is part of the problem solving. It was only after I fixed the problem that a carburetor repair person suggested that this was probably why Weber modified some plates in the 80?s with a 8 ? 10 mm hole in the middle. Unfortunately Messers Weber don?t tell everyone why they did this modification.

NOTE: Obviously all of these fuel checks are better if carried out shortly after a run so wet fuel can be seen when the carburetors are removed.

europatek wrote:Ok, calling all Weber experts. I've looked through my Weber tuning books and the archives here but cannot find anything conclusive for the problem I have. Recently purchased and rebuilt a pair of 40DCOE27. OE fitment on Alfa's. The carbs look great and I used Webcon service kits. Installed and running great, however after running the front carb starts dripping fuel at the mounting to the head, past the O rings. I've removed the carb twice and checked/replaced everything I can think of and all looks good. I can leave the car sitting with the carbs full and no leaks. Idling and cracking the throttle and no leaks. It seems to only occur after I've been for a drive and after shut off and a few minutes standing it starts to leak - not dripping but quite wet.
So, anyone with any good ideas?