Carburettor Woes

[rob83ke70]

I'm a man of many different vehicles and many different mechanical problems, which I'm sure is taking years off my life :)

 

I have a suzuki swift cino 1.3lt SOHC with a carburettor, and it jerks and hunts terribly when driving on the highway (and chomps fuel too) but is quite ok when driving in town. The carburettor has had a kit put through it (by myself) the ignition timing is quite ok, it starts and runs really well in town.

 

Now the question I have, when driving on the highway, at a constant speed, obviously not much load on the engine if any, what circuit would it be running on in the carburettor? I'm assumming the main jet would be the culprit, although a fellow I met the other day seemed to think the idle circuit if there is no load. The throttle butterfly would be open past where it would run on the idle or progression circuits so I'm thinking main??

 

I figure the problem has got to be a lean air fuel mixture, over advanced ignition timing, or an EGR problem, now as the ignition timing is good, I'm thinking probably a blocked jet of some sort maybe??

 

any ideas?

 

Robert.

[KEI069]

the first thing i would do is replace the fuel filter, for some

reason suzuki's have a habit of blocking fuel filter s and having

a very similar problem to what you stated.

its worth a shot

cheers justin

[Old fella]

I'm a man of many different vehicles and many different mechanical problems, which I'm sure is taking years off my life :)

 

I have a suzuki swift cino 1.3lt SOHC with a carburettor, and it jerks and hunts terribly when driving on the highway (and chomps fuel too) but is quite ok when driving in town. The carburettor has had a kit put through it (by myself) the ignition timing is quite ok, it starts and runs really well in town.

 

Now the question I have, when driving on the highway, at a constant speed, obviously not much load on the engine if any, what circuit would it be running on in the carburettor? I'm assumming the main jet would be the culprit, although a fellow I met the other day seemed to think the idle circuit if there is no load. The throttle butterfly would be open past where it would run on the idle or progression circuits so I'm thinking main??

 

I figure the problem has got to be a lean air fuel mixture, over advanced ignition timing, or an EGR problem, now as the ignition timing is good, I'm thinking probably a blocked jet of some sort maybe??

 

any ideas?

 

Robert.

 

 

G`day mate, your problem sounds to me to be either a dirty fuel filter or a fuel pump that is on its last legs.

Pretty doubtful on jets or the problem would be there city an highway driving.

I`m not familiar with suzuki, but some cars run more than one fuel filter so you may have to consult a manual or a dealer to find out where they are.

Some fords run a pick-up screen in the tank, then a line filter and then a filter where the fuel line joins the carby. Even though dealers charge for cleaning/replacing them during services, they sometimes don`t do the job, if you catch my drift.

Anyway, thas my two bob worth, so good luck.

[rob83ke70]

two fuel filters.... you are picturing a subaru brumby there!!

 

The swift's fuel filter lives in roughly the same spot as my subaru, under the car near the tank, and it was replaced 5000km ago, but that being said, I wouldn't be surprised if it was blocked up again. I don't know when the last time it was replaced before that was, but the filter had fallen apart internally and muck was going through to the needle and seat causing flooding.

 

I have to say that any dealership that I personally worked at, if you were charged for it, I had done it!! But that being said, I've come across lots of places since that are less scrupulous....

 

Robert.

[Felix]

Could possibly be something to do with the emissions vacuum circuit.

 

Not sure about your suzuki, but some gearboxes have a switch on 5th gear which triggers a change in the vacuum circuit used under highway cruise conditions.

[rob83ke70]

I have taken it for a drive today and lo and behold, could not fault it.... my brother drove it a few days ago and he reckoned it was undrivable on the highway....

 

I drove for about 10 minutes each way at around 100km/hr and it was perfectly ok. Apparently you have to drive for a fair bit longer than that for it to start playing up.....

 

maybe a fuel filter?

 

Robert.