Elan storage problem: stale fuel in Webers

[smartd]

Hello, I wonder if you could possibly advise me on this. I've had the same Elan ser. 3 SE for the past 32 years and it has rarely been used lately, but always used to go like a bomb. Over the past 20 years or so, the once or twice-a year start-up has become more difficult and the running more erratic. It has lumenition and the compression is fine, valve timing and tappets fine, good fuel pump pressure too. The poor starting was eventually traced a couple of years ago to gumming of the smaller carb jets and seizing of the 4 tiny ball valves in the accelerator pumps. Once again I have had to unseize these ball valves and have removed and carefully cleaned all of the brass jets in both carbs. I now have good starting again with a bit of choke as usual, but the engine revs very poorly when the throttle is opened [using the choke here helps a lot!] and only smoothes out when on the main jets, over 3000rpm. I am now about to remove and strip the carbs completely and look to see if there is any more gum unaccounted for. Question is, is there any particular place I should be looking for fuel obstruction, apart from the brass jets themselves?

Hope someone can help, many thanks,
dave

[Howie146]

Hi Dave, worth checking the pump discharge valve located in the bottom of the float chamber, this a little one way valve that is part of the pump jet circuit. Take out the valve accelerator pump and the balls and weights you have already removed and use carb cleaner spray and or compressed air and make sure the adjoining galleries are clear, It certainly sounds like its the accelerator pump circuit that is still giving problems assuming no air leaks and idle is clean.
Hope this helps
Regards
Neil

[smartd]

thank you Neil. I thought I was "done" when I could see the balls moving and fuel coming out both demountable jets in their galleries.
However now I come to think of it there was some disturbance of the fuel down near the intake valve in one of the float chambers. This could mean that fuel was also being pushed back into the float chamber at the same time because the intake valve was stuck open, thus partially denying the outlet jets. I will check this next.

lovely illustration by the way, can you tell me the source?
Regards, dave

[seriouslylotus]

Had the same problem with a 1996 Bimota I just bought.
Tried the usual carb cleaning techniques but that didn't work
Ended up with an ultrasonic cleaner - wow clean as a whistle and starts on the button every time now
Well worth the investment!!!

[Howie146]

Hi Dave pic courtesy of google. There will be some disturbance seen in the float chamber as the discharge valve has a back bleed hole, in the DCOE18 its 50 and in the DCOE31 its 40 so some fuel is returned. As the above poster rightly says, it may require ultrasonics if the blockage/restriction can't be found. I'm afraid it's a case of working your way through methodically and checking every jet,drilling and passageway.
Regards
Neil

[smartd]

Gentlemen, thanks very much for your advice. Lots of cellulose thinners and compressed air and all is serene once more. No spitbacks in the carbs and no bangs in the exhaust, tickover very sweet and only a brief use of choke to start.
I came across a couple of things that might be useful to others. [1] An article possibly on this forum that recommended synchronising the butterflies by looking down the progression holes with the covering plugs removed. This is VERY sophisticated compared with doing it by ear. A small pen torch is required [or 2 if you have them], pushed into the carb mouth and rested on the central tube that the main jet squirts into. The view of the progression holes is illuminated from within the carb's throat and you can adjust and sync the butterflies with sub-millimetric precision. It also allows you to check that there is no twist in the butterfly shaft, i.e. the two butterflies on a single carb are the same as each other. [2] I bought authentic service kits made by Weber. It was noticeable that the replacement taper-tipped mixture screws for the slow running have a different, much sharper taper than those originally fitted to my carbs. This means that the default "three-quarters of a turn open" position for commencing the slow running mixture adjustment is nowhere near sufficient. You need to start off with about 2 turns open to get a reasonable starting place for tuning.
Hope this helps someone else

Thanks again
dave

[Howie146]

Hi Dave glad you got sorted and she's runing sweet again. On the subject of the Idle mixture screws the ones they supply in the kits now as std are for the later 40DCOE151's For info I deal with Anthony at Fastroadcars (authorised Weber dealer) and I tell him the carb number ie; 40DCOE18/31 and he supplys the kits from Weber with the correct (early taper) idle screws already in