Suzuki 4WD Club of Victoria

Hi Fellas.
I have had carb icing problems with my Sierra (g13a) from day one. It normally happens at highway speeds in fifth gear, almost always early morning and only in cold weather.
The symptoms are similar to a fuel blockage, surging and hesitating. If I ignore it and keep driving, the fuel consumption increases dramatically and the motor will eventually stop.
I have tried many things over the years to fix it.
Take off the fan and use electric fan.
Remove the automatic choke.
New thermostat.
Partially cover the radiator.
Replace the hot air pipe.
Make a larger and more dense heat exchanger on the extractors.
Put a larger hot air pipe from the extractors to the air intake.
Put a woollen sock on the hot air pipe.

Its time to start thinking outside the box.
Light aircraft engines must have carb heat controls. (the older aircraft engines that have carburettors) They have heater plugs in the carburettors. Also some motor bikes , KTM that I know of and others.

Wondering if a diesel engine glowplug and timer some how fitted to the carby might be something to try.
We have some excellent lateral thinkers in the Suzuki Club.
Any ideas? ( besides a efi engine)
Regards. Wayne.

Hi Wayne. All I can suggest if google. The first YouTube clip I found shows a bloke using tin foil to loosely wrap around his carb and fuel line essential reflecting some of the engine heat back into those components. You'd need something a little more reliable than tin foil but might help.
Brenton.

extend the fuel line to run over the engine before it goes into the fuel pump. when the fuel decompresses when it goes into the carb it cools down a certain ammount so if it was pre heated it could come down that same ammount without freezing

12v heat pad?

https://www.ebay.com.au/itm/Waterproof- ... ctupt=true

Can you re-route the air intake so that rather than it sucking air from the colder part of the engine bay, it could suck air from behind the radiator or place the airbox on the other side where the jack mount is so the intake pipe crosses over the exhaust manifold?

get a piece of the heat-proof corrugated foil tubing (similar to the original hot air induction)
this is available from Bursons

clamp one end onto the exhaust manifold and jam the other end into the air intake, this will cure your freezing issue.
Jinxy had this issue and this was the most cost effective cure, and you certainly won't be needing it in the summer.

the issue with taking the air from the radiator is that it won't be hot enough to de-ice the carb, and runny the potential issue of being moisture laden, exacerbating the original issue

I have another angle on this.

I think your "commercial" 1.3litre carb has a manual choke, yes?

Does it have coolant hoses running up to carb? if so, do you have flow in the them? These hoses don't require the thermostat to have flow in order to function, same as the heater core.

The factory 1.3 auto-choke carb is warmed by engine coolant. This should be enough to prevent icing if the factory inlet ducting is still in place (taking air from the back corner of the engine bay beside the factory battery location)

Very few Sierras still have the original warm air ducting in place from the manifold to the air inlet and few suffer from bad icing problems.

Jinxy didn't have any inner guards, soo that won't have helped it's case.

Hi Fellas.
Thanks for all your input and ideas.
Up until joining the Suzuki Club my Sierra was stock standard. (as far as I know)
It now has Genie extractors.

I bought it second hand with 28,000 Km on the clock.
It had an automatic choke which I thought was the problem. I tried tying the choke butterfly open, but that made no difference.
It had the original exhaust manifold with a hot air box on it. Always had the hot air intake pipe from the hot air box to the air intake.
Suzuki must have anticipated a problem, because there is a manually operated 3 position switch on the air intake. I can manually switch from all cool air (from behind the battery box) to half cool half warm, to all warm air coming off the exhaust manifold. (hope that makes sense)
I have a piece of 50mm pipe welded to some steel plate which is bolted to the extractors. I have a large hot air pipe from the extractors to the air intake. Better than the original (in my opinion)

Sierras were sold in many countries very much colder than Aus.
Must be a problem unique to my engine.
I have learned to live with the problem over the years. The solution is to just stop and turn off the engine and wait 5 minutes.
I have noticed that the float bowl feels icy cold to touch when it happens.

It rarely happens in daytime. I leave Melbourne at 5.00 am and drive to Daylesford, or Ballarat or Nagambie, nearly always happens once I get onto the highways and in fifth gear.

Probably does not happen to other Sierras, because few would drive the distances I do at the times I do.
Regards. Wayne.

So air into carb is hot enough. Surely fuel is being super cooled along the pipe?

Hi Fellas.
Thanks for your ideas and comments.
I reckon I have used all my options as far as hot air into the airbox.
I have now re routed the hot water that would have gone to the wax pellet on the auto choke. I have attached a copper tube and copper plate to the side of the float bowl. The hot water that was for the choke now runs next to the float bowl.
I have also put a temporary shield around the air box. Also blocked off the air that would be coming thru the right hand quarter of the grill. ( between the right hand headlight and the radiator.)
Surely the fuel would be kept warm from the fuel pump, because the fuel pump is bolted to the head. Its a short distance from the fuel pump to the carby (via a small final filter).

When did car manufacturers stop using carburettors? Did fuel blends change with the introduction of efi engines.? Do we get summer and winter fuel blends in Australia as they do in colder countries?
Is there a fuel additive available that might help?

Going to Daylesford early tomorrow , its going to be frosty. It will be a good test for these changes.
Regards. Wayne.