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+--- Thread: Chummy starting issues - possible carb (/showthread.php?tid=9355)
Chummy starting issues - possible carb - RupertW - 10-05-2024
Afternoon all, I've been having an unsuccessful time getting my chummy to run so hoping for some thoughts and advice. I'm fairly sure it's carb related but to complicate matters I've just put on a new ignition system.
The car had previously been running okayish, but on an emergency backup distributor switched and crudely setup at the roadside, which I've now replaced with an electronic setup. The electronic set-up appears to be sparking nicely, only set to TDC as I haven't had the car running, and I'm fairly sure I have the leads in the right order.
The reason I think it's carb is that the plugs are almost completely dry. It will occasionally fire up momentarily particualrly with a bit of persuasion from an aerosol can. There's plenty of fuel getting through to the main bowl and it's not obviously leaking from anywhere.
I'm assuming the most obvious thing is a blocked jet of some description, although I'd be annoyed as I've fitted a fuel filter. The carb is a 22fzb I think and I'm struggling to find much guidance online for these (at least compared to the later carbs). The top part of the slow running tube seems to have a small split at the bottom I assume from it being screwed down too far, but I can't imagine this would stop it running at all given it was quite happy previously?
I've taken the carb off the car, but I'm a bit nervous of damaging it or making things worse by starting to fiddle around without knowing what I'm doing. Basic question, but can anyone tell me in the first instance how to remove the jets for cleaning and inspection?
Any help or thoughts much appreciated!
RE: Chummy starting issues - possible carb - AustinWood - 10-05-2024
If this is an updraught Zenith 22FZ then flood the carburettor with by lifting the float needle, then crank the engine by hand, maybe 8 compessions with the ignition off.
Ours usually starts imediately after that.
If you think there's no fuel making it to the cylinders take out the plugs and pour a little petrol into each cylinder.
RE: Chummy starting issues - possible carb - SJT - 10-05-2024
I have just had a similar issue, my military seven would not start, I checked all of the usual, but it would still not start. Charged the battery well and it started first time.
There was not enough charge to turn the starter and produce a good spark.
SJT.
RE: Chummy starting issues - possible carb - Howard Wright - 10-05-2024
Hi
Cleaning the jets is fiddly and you get your hands soaked in petrol but not difficult. Here is a link to a Zenith service guide which may help.
https://zenithcarb.co.uk/zenserviceguide
As Jim has mentioned, flood the carb and it should start. My RK starts virtually every time on the handle using this method.
Cheers
Howard
RE: Chummy starting issues - possible carb - RupertW - 10-05-2024
Thanks both, the carb is well flooded, and I don't currently have a starter fitted and have a well charged newish battery.
The plugs don't smell at all of fuel so I'm still leaning towards that
I've also checked that it's sparking on the compression stroke so I've not got it out by 180 degrees!
RE: Chummy starting issues - possible carb - Howard Wright - 10-05-2024
Hi
Starting a car with electronic ignition by the handle may be problematic (or so I’m told by Powerspark). Apparently their ignition works on a series of pulses so you may need to crank quite quickly, in addition the timing needs to be set by strobe rather than a static timing light.
I’d put a points based dizzy on, set the points to just start to open at TDC and you may find the car starts.
Cheers
Howard
RE: Chummy starting issues - possible carb - RupertW - 10-05-2024
Thanks, I think tomorrow I'll put the old distributor back on just to rule it out - my backs about gone for today!
It does spark quite nicely even when being turned over quite slowly by hand, and attempts to bump start also made little difference. I've only ever done timing by feel but perhaps I need to be more scientific about it.
I've taken both jets out now and they look totally clear. When I last used the car with the old distributor it was also extremely reluctant to get going but ran fine once it was going.
RE: Chummy starting issues - possible carb - Ruairidh Dunford - 10-05-2024
If needed, I can crank start most of the cars I have fitted an electronic ignition to with 1/4 turn, on the starter it's simply a flick on the button.
If I bring the car up to a compression stroke, when it's warm, the car will also start simply by switching the ignition on!
RE: Chummy starting issues - possible carb - Ruairidh Dunford - 10-05-2024
Also, electronic ignitions will not fire if the battery falls below 6v, this can happen on a soft battery whilst cranking, or with a poor earth... they normally start the minute the starter motor is released, quite strange when you first experience it!
RE: Chummy starting issues - possible carb - Howard Wright - 10-05-2024
(10-05-2024, 07:17 PM)Ruairidh Dunford Wrote: If needed, I can crank start most of the cars I have fitted an electronic ignition to with 1/4 turn, on the starter it's simply a flick on the button.
If I bring the car up to a compression stroke, when it's warm, the car will also start simply by switching the ignition on!
Hi Ruaridh
I think it is manufacturer dependant. My special running a ‘Distributor Doctor’ distributor starts, like yours, with a quarter flick of the handle. The ‘Powerspark’ distributor on my van will not start on the handle, no matter what! It is, as you say in your second post, necessary to have 6 volts or thereabouts.
Cheers
Howard