4k failure! (but why?!)

[rollaholic]

so i was driving the starship round last night, dutifully giving it plenty of stick as required by law. then as i was attempting to keep up with a gently accelerating rav-4 at the lights, i lost power. (was a short fall)

awful idle, and zero response from throttle. lots of jerking as engine ran normally briefly, then went back to running like a bag of arseholes.

after 30 seconds or so of this, with me wondering if the missus and i were going to spend the next 3 hours walking home it came right and we made it home.

then this morning on the way to work, it started playing up again. oh noes! to make matters worse, this time it died completely and i was forced to mount the footpath to get out of traffic. good thing the star-whore does a good imitation of an ATV. refused to start for several minutes, but eventually roared into life and got me MOST of the way to work. then it went through the whole performance again, only this time it was permanent. roll starting no help etc.

so after work i went back to check it out, of course it started first pop and has run flawlessly since then. i took the fuel pump off, it seems to have decent operation (is there a more scientific method of checking these things?) and the fuel filter looks new-ish. my gut feeling is its a fuel problem, so im looking for some insight / common problems perhaps?

its an 84, single carb 4k with points ignition. the ignition side of things is all fairly new, and the whole car has been running like a trooper for a couple of months now.

ideas welcome!

[xsspeed]

she'll be right etc

that is bizarre, whats the condition of the carb? could it be overfuelling and blowing out the spark so to speak

when it dies does it crank over at all?

[Mr Revhead]

iced up carb?
got a warm air intake?

[fangsport]

iced up carb?
got a warm air intake?

bet me to it. had the same issues driving one of my KE70's to Dunedin in the fog. unfortunately, a large volume of fuel dissapeared each time it died and we used 60 litres to get there.

[rollaholic]

interesting! it has been cold each time its done it.

it does have the winter / summer switch on the intake, i've got it on winter but the pipe to the heat shield isint in the best condition.

im a bit scared to drive it at the moment for fear it craps out in traffic / going up a hill

is the carb likely to ice up when the engine is warm though?

[Mr Revhead]

yes
coz it ices up inside due to the air flow in the throat
think windchill factor + some moisture!

my ke70 would do it on the motor on way home, well and truly hot engine

[rollaholic]

yuh i guess petrol atomising / evaporating is awesome for sucking the temp out of shit too.

stupid winter

will have to investigate getting that hose a bit more air tight i guess

[KinLoud]

Yep - venturi in carby throat and evaporative cooling by the fuel can cause moisture in the air to freeze in the carb throat and around the butterfly.
Most often happens at small throttle opening or at idle.
Often happens on carby piston powered aircraft - so you select heated air for descent etc.

Ken
Auck
021 408 863

[frost]

WHAT!!! a 4k failed!!?!?!! did hell freeze over too?

a mate with a dx had to run hot water hose coils around his carb to keep it from freezing over, that was when he did road trips way down south.

[rollaholic]

ken are you saying my throttle is responsible? ><

the first time it happened was probably more like full throttle, haha!

[KwS]

ken are you saying my throttle is responsible? ><

the first time it happened was probably more like full throttle, haha!

more throttle, more air, more cold...?

[RS13]

I had a similar issue with a KE70 wagon, would run fine sometimes but then not want to rev/sound like it was on 3 cylinders.. I sold it to a guy who changed the fuel pump, he said it was fine after that.

[rollaholic]

ken are you saying my throttle is responsible? ><

the first time it happened was probably more like full throttle, haha!

more throttle, more air, more cold...?

i was having a laugh about his signature more than anything

my theory is at wider throttle openings there is too much fuel flowing for anything to freeze

but, the first time i had been sitting at the lights for a bit so perhaps it frosted up then

anyway, i had a look at the warm air intake (this seems so backwards, haha) and the pipe is in fact just about perfect. and im 95% certain it was set to winter all the times its spat the dummy... so slightly bemused. drove it round a fair bit tonight, has been fine - though not as cold as previously.

my first throught was fuel pump too. but as mentioned i pulled it off and it seemed fine! i really need it to fail again so i can have a tinker while its not going

[Lloyd]

More air flow through the venturi means it gets colder. Water from the air can ice, and the cold air doesn't help with fuel atomisation either.

[RomanV]

so i was driving the starship round last night, dutifully giving it plenty of stick as required by law. then as i was attempting to keep up with a gently accelerating rav-4 at the lights,

If not for having driven a 4K powered starlet, I'd be thinking you were exaggerating on this point.

But it was one of the most amazingly fun things about it, viva la 4K!

[rollaholic]

More air flow through the venturi means it gets colder. Water from the air can ice, and the cold air doesn't help with fuel atomisation either.

yeah, i get it. im just slightly bemused for it to happen when the system that was designed to prevent it is in perfect working order... and its not like auckland gets THAT cold.

[79rolla]

intereting that its cold enough to do that in aux tho?? iv never had a problem on frosty mornings ect and iv just got a ramflow mushroom ontop of my carb... but did have a few issues with my old carb being $&#$%...

ill have to make sure i take the standard inlet if i go to the snow then lol

[Mr Revhead]

moisture in the air has a lot to do with it.
used happen to me only on one certain part of the motor way, and area near a river with lots of trees. was often a bit misty

[Lloyd]

Turbos help keep it a little warmer. Just if you get stuck for how to fix it

[rollaholic]

haha, i knew i could rely on TS for constructive ideas!

wtb EFI