OldMaster

Series 3..2,25 petrol with a new fuel pump and serviced Weber. Thought I would be clever and fit an in-line fuel filter and positioned it up near the carb.. Ever since I have had the engine cut out and very reluctant to start again..particulary it seems when warm, but I am not sure this has a bearing on anything. The tappet clearances are done, the points/condenser/coil replaced..the dwell is 55 degrees, it likes 6 degrees BTDC and I am set for 2% Co emission on my gas analyzer...she starts from cold..and when she does continue to run, sounds spot on..so I am think a fuel problem for sure...? Have I created an air lock situation with this fuel filter (the best it ever gets is half full) and should I place it in a completely different position to the one it is in..or just take it out and throw it away!!!

..normally set it to around 2%!

OK, thanks all!! I have finally got there. It is true that it was running on a faulty fuel pump for what must have been some time..and that was replaced end of last year. It was difficult to solve it just by process of elimination. The problem was certainly unburnt fuel, lack of power, stalling and back firing when warm... Anyway, replaced the points which were very badly pitted..this was odd in itself because they were not that old. Changed the coil and the condenser as well. Set the points with the Ducellier out of the lump and returned it to a marked position... Turned the key and "Bingo"..she started and ran. Using the Gunson analyzer and a timing light I was able to set the dwell, CO and timing and took her for a run..transformed..even when warmed up!! Will still do the tappet clearances and change the oil because I guess the last lot has had a hard time!! Thanks again!

I would guess if not Paddocks or Craddocks, Exmoor trim may be able to help?

Yes, valve clearances next..I have ordered the rocker cover gasket!!

Yes I am fairly sure it is unburnt fuel..I can smell it but I am now at my wits end!! I have replaced the coil, I have replaced the condenser, points and leads. First off would not start at all..OK, the timing might have changed although the distributor was replaced exactly so it should have been good enough to at least make an effort until I could get the dwell meter on it.. Because the Weber has been mucked around it was set to default...mixture 2 turns out and throttle stop around 1.5 turns of throttle opening... Cough, splutter, bang....attempted restart several times..eventually just about managed to tick over long enough for me to read the timing light... OK, jumping around of course but still about 6 degrees BTDC (low compression) and the way it always ran really well..but something odd..I painted the notch on the crank pulley silver to make reading easy....yes it was jumping around but also disappearing because the light was going out and then switching back in....so, intermittent spark then??? cap? rotor arm?...all look good and not that old..timimg chain? valve clearances? ..grabbing at straws now! Up until a week ago..at least when cold the timing light reading was rock steady!! Baffled now?

Thanks guys..this is really useful..."rebuilding" distributor today and will check connections to coil again...strange phenomena this..left it Tuesday pm just refusing to start..occasional fire with the choke pulled open or throttled depressed but otherwise nothing... Go out Wednesday am, first turn and she starts and runs!! Been building engines since I was a kid..got me baffled this time..but still suspicious of the carb!!? As for you RAF guys..and on tax payers money!!!!!

Thanks for the help guys..keep'em coming! Got the new condenser today and will change the whole points assembly...keep you all posted!

I have a Series 3 2.25 petrol which has recently taken to squirting flame out of the exhaust, backfiring and stalling..now refuses to start at all! Given the weather I thought carb icing but now have my doubts. OK, tests and symptoms...have a timing light and Gunson analyzer for dwell, co, rpm etc... It is fitted with a weber..only around 20,000 miles old and a new fuel pump two months back...dwell reads correct and timing as low compression is stable at 6 degrees BTDC. Compression check shows fairly even compression on all bores and I have fitted new plugs/leads... Cleaned the carb and idle jet as best I can. Usually starts pretty promptly.....like this morning....runs for about 10-15 minutes reasonably smoothly and then it all goes horribly wrong!! Let my foot off the pedal and don't stand near the exhaust as it shoots a flame out and then starts missing and stalling...I intend to change the points again and fit a new condenser but my experience is telling me carb somehow.. when it does first run from cold she is smooth and picks up well. So something is changing dramatically in the warm up period....any clues anybody...Help!!!