Cold Starting Problem Part Ii

[Guest Andy Sparrow]

Thanks to you all for previous help on the valve clearances which are now a little quieter, the problem with the rough running was that the ignition timing had somehow slipped about 25 degrees out.

However I still have this steadily worsening problem that is exhibited as follows;

After a completely cold start she runs ok for about a minute then starts to die. So far I have checked auto choke settings (ok) in fact altering the choke flaps during the problem has no effect what so ever, so the cause is not over or under choking. Also checked the phasing and fast idle, float heights.

Replaced the leads plugs & crankcase breather valve. (this is a '82 based engine with new 38DGAS)

Has been starting fine until around christmas time, not sure what changed then ... ?

The current theory is that it could be carb icing, however if I switch off & immediatley re start all is well ....

no need to wait at all. What ever is causing this can be driven through by keeping the revs up for a further 2 mins or so - then all is well.

Only exibited at completely cold start no other running problems exhibited.

Could it be something other than carb icing as it is getting worse, it used to be an intermitant problem but is now exhibited at every cold start. Bert Holden carb specialists, state it is most probably electrical but theres not much I havent changed only the ignition module & coil are original.

 

Any one got any further thoughts ?

 

cheers

[Longboarder]

Still sounds like a fueling problem. Had something similar once when driving in the rain. could keep it going on the accelerator pump but water in the float chamber was messing up the running. Suggest a clear inline filter just before the carb so you can see what fuel flow is doing and tighten all fuel line jubilee clips.

Nigel

[Bob Tucker]

Hi Andy,

I've used 2 DGAS carbs on my Hood (not at the same time!) , & had small problems with both.

The first was simply one blocked idle jet, obviously there's 2, clear them both out.

The second was the anti stall device. It looks like another pump jet cover,

but has a vacuum pipe connection. You don't need it, disconnect it & block

the vacuum pipe leading to the manifold.

Bob.

[Guest Robin Allison]

Andy,

One thing you could check is for air locks in the fuel lines. I had a similar fault on my RS2000, every time it was started. Just by chance i noticed that there was air in the fuel line to the carb. When the engine was stopped the fuel would drain back to the tank. I re-made the pipe ends which stopped the fuel draining back.

 

Rob..