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+--- Thread: Why won't it start (/showthread.php?tid=2235)
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Why won't it start - rubyman - 15-01-2019
Carrying on from my last post when I found the petrol pipe, pump to carburettor half blocked with solder & no banjo bolt filter, I decided to strip the carb cleaned all the jets by compressed air and then rebuilt the carb. Looking at diagrams of the Zenith 26AV carb it shows washers on the main,compensating & slow running jets there's no washers on mine, and there is no progression jet & plug fitted. Before stripping the carb the engine run perfect once started, it did take a bit of starting when cold no problem when hot. Now it will not start, when trying to start petrol drips from the choke end of carb the choke shuts fully & opens fully and the plugs are getting wet with petrol, I have checked all compression's 110, timing set at TDC,, firing order 1342, point gap 12 th tried new pugs with 16 th gap, plenty of petrol in tank. What am I missing
( 1938 Ruby 750cc )Thanks for all replies
Graham
RE: Why won't it start - Reckless Rat - 15-01-2019
Sounds like an ignition problem. Take one of the plugs out touch it to earth and see if it's sparking when you turn the engine over with the ignition on. Don't hold the plug lead while you do it!
RE: Why won't it start - rubyman - 15-01-2019
(15-01-2019, 03:13 PM)Reckless Rat Wrote: Sounds like an ignition problem. Take one of the plugs out touch it to earth and see if it's sparking when you turn the engine over with the ignition on. Don't hold the plug lead while you do it!
Forgot to mention good spark at all plugs
RE: Why won't it start - Chris KC - 15-01-2019
Graham, what have you changed since it last ran OK?
If you removed the carb to strip it, are you quite sure the new joint to manifold is airtight? A small air leak here will kill starting.
p.s. 1/16" plug gap? I would have used 20 thou; but I doubt this is your problem.
RE: Why won't it start - Robert Leigh - 15-01-2019
(15-01-2019, 03:08 PM)rubyman Wrote: Carrying on from my last post when I found the petrol pipe, pump to carburettor half blocked with solder & no banjo bolt filter, I decided to strip the carb cleaned all the jets by compressed air and then rebuilt the carb. Looking at diagrams of the Zenith 26AV carb it shows washers on the main,compensating & slow running jets there's no washers on mine, and there is no progression jet & plug fitted. Before stripping the carb the engine run perfect once started, it did take a bit of starting when cold no problem when hot. Now it will not start, when trying to start petrol drips from the choke end of carb the choke shuts fully & opens fully and the plugs are getting wet with petrol, I have checked all compression's 110, timing set at TDC,, firing order 1342, point gap 12 th tried new pugs with 16 th gap, plenty of petrol in tank. What am I missingHave you got a modern rotor arm? I have known them to fail by shorting through the centre so that the spark goes straight to earth on the central spindle. It happened on an MOT on a friend's car. I sorted it instantly and the MOT man's flabber was ghasted!
Thanks for all replies
Graham
Robert Leigh
RE: Why won't it start - Steve Jones - 15-01-2019
(15-01-2019, 07:58 PM)Robert Leigh Wrote: Have you got a modern rotor arm? I have known them to fail by shorting through the centre so that the spark goes straight to earth on the central spindle. It happened on an MOT on a friend's car. I sorted it instantly and the MOT man's flabber was ghasted!
He says, above, that he's got a good spark at the plugs. He wouldn't have that with a duff Rotor Arm.
Steve
RE: Why won't it start - Chris KC - 15-01-2019
Perhaps if you stop calling her 'it'?
RE: Why won't it start - Peter Naulls - 15-01-2019
How old is the petrol Graham? If in doubt empty the carb bowl and refill with fresh petrol.
Try starting it with the handle not the starter - the starter will reduce the spark if the voltage is at all reduced.
Peter.
RE: Why won't it start - John Mason - 15-01-2019
How long is it since the engine last started up. If it's 6 to 8 weeks it could be stale petrol. Remove the float chamber and discard the petrol in it. Fill with new fresh petrol (petrol that is new or kept in an airtight container) then try the starter again with and without choke. If it runs you have proved its the old petrol. If it does start don't discard the old petrol in the tank it will probably run on the old once the engine is hot.
You beat me to it Peter we must have both bean typing it in at the same time
John Mason.
RE: Why won't it start - andrew34ruby - 15-01-2019
The inlet manifold and tops of pistons might be awash with far too much petrol. 'Flooded'.
If there is a spark at the plugs, and plugs are wet with petrol, then flooded sounds most likely.