jimi.hendrix Posted May 19, 2022 Share Posted May 19, 2022 Issue - It starts but has a misfire after 3 seconds and will not run on idle or main jets but will run on pump jets but back fires and puts flames out of the carbs! Was running OK but the last 3 years has a pop from the exhaust several seconds after the engine has stopped.No oil from breather in catch tank and engine has not burnt much oil in the past. Done 11 miles last year and 34 miles per year in the previous 2 years. Dry stored in garage. Engine Spec - Standard Caterham sprint spec from 1989 with NODIZ 3D ignitionTests done:-Compression check psi warm with throttle open using Chinese compression tester - 140,130,135,135 - (I've not done a wet test yet)Leakdown test (using rubbish Chinese low pressure version) - valves good, cooling system no bubbles, no leak between cylinders, but noticeable leak from block and rocker box breathers.Ignition timing good on timing light - Good spark but new coil pack and plugs just to check. Throttle position sensor signal working and calibrated.Fuel system flushed and new fuel used plus carbs stripped and ultrasonic tank cleaned. Fuel level in carbs checked. Fuel pressure checked. New seals on carb to manifold.Supply voltages and earth bonding checked.Any ideas what the problem might be? I have sticking piston rings or glazed bores left on my list but thought I'd ask opinions before starting a full engine strip. Link to comment Share on other sites More sharing options...
SM25T Posted May 19, 2022 Share Posted May 19, 2022 It's probably in shock after two impossibly quiet years !!! Link to comment Share on other sites More sharing options...
Roger King Posted May 19, 2022 Share Posted May 19, 2022 If it runs on pump jets but not mains or idles I suggest you start with the carbs - float levels, blockages, etc. Also check fuel delivery. Link to comment Share on other sites More sharing options...
Wrightpayne Posted May 19, 2022 Share Posted May 19, 2022 I helped Tazio re-commission a crossflow that had stood for many years - the steel fuel tank was full of rusty sludge! Link to comment Share on other sites More sharing options...
jimi.hendrix Posted May 19, 2022 Author Share Posted May 19, 2022 Thanks for the comments SM25T is probably correct but think I'll check the fuel system again before dropping the sump. Link to comment Share on other sites More sharing options...
HendrixsWhiteStratReturns Posted June 1, 2022 Share Posted June 1, 2022 Hi HendrixI had issues with my 1700SS for a long time (misfire ) and eventually it was traced to carbs needing a rebuild plus a dodgy ignitor in the Aldon Dizzie(Sorry just re-read an saw that you have have the carbs done). Link to comment Share on other sites More sharing options...
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