car keeps running on!!!!

[81pw]

my engine keeps running on when i turn it off for couple seconds or even longer sometimes. ive put a carby off my other sigma and it still does it. the cut off solenoid works, its had a tune up, new leads new plugs.timmings right, and i just put a new head on. no vacuum leaks. anyone one no my promlem?? maybe electrical problem?

[karl_2ltgc]

Too much ignition timing advance.

[81pw]

change the dizzy see if that changes anything?

[karl_2ltgc]

Adjust the timing.

Use a timing light on it to make sure its ok.

[crystalmeths]

check the fuel to running to lean can also cause it to run on

[tandanus]

As above - too much advance. Or dirty plugs. If you have a dizzy its possible that the mechanical advance isnt returning properly (sometimes they stick). Get in there and see if it moves freely.
T.

[Frosty]

If the engine runs as normal for a few seconds after the ignition is supposed to be switched off (ie turn the key off)..then your ignition has probably been shorted, and the only reason it stops at all is because the idle solenoid (which you stated IS turning off) causes it to run out of fuel.

try turning the engine off and pumping the accelerator repeatedly. if it runs on for as long as you pump it. your ignition is not turning off properly. (which would probably be a job for an auto electrician)

[81pw]

yea timings right. not running lean. when i turn it off it runs really rough kinda sounds like a diesel for couple seconds then a loud sucking noise from the throat of the carby. then it turns off.

[tandanus]

Sounds like pre-ignition. My Hilux does this sometimes. Sounds like its running backwards then smells like fuel/oil mix when it stops. I just let it go or stall it if in a hurry. Give the plugs a good clean (or buy some new ones ), or run some of that fuel injector cleaner thru it or chuck some 2 stroke oil in the tank (can you still buy that stuff ?). Whats happening is that youve got stuff in the cylinder somewhere that is so hot that it sets the fuel/air charge off without any ignition. Usually carbon deposits. Carbon deposits can get hot from lean mixture and/or too much ignition advance. Get rid of them. Then find out why theyre there (rich mixture somewhere in the rev range?). Fixed.
T.

[DanTurboLancer]

run some of that fuel injector cleaner thru it or chuck some 2 stroke oil in the tank (can you still buy that stuff ?). Whats happening is that youve got stuff in the cylinder somewhere that is so hot that it sets the fuel/air charge off without any ignition. Usually carbon deposits. Carbon deposits can get hot from lean mixture and/or too much ignition advance. Get rid of them. Then find out why theyre there (rich mixture somewhere in the rev range?). Fixed.
T.[/quote]

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I was thinking the same except has said he has put a new Head on it.
But why would you put oil in your petrol tank??

So does it happen all the time?
Or just cold, just hot,
only after giving it a hard time and reving hard?
Wet day,
Long drive, short drive?


How does it drive otherwise?

Can you feel lack of power, smell fuel,
Does it have trouble starting?
Again cold Or trouble starting all the time?

Just trying to establish if it has a Vacuum leak or lean run.
Or perhaps timing/ ignition prob.

Best way to check Vac leak for the inlet side of things isnt always the soapy water, try spraying Petrol, if revs pick up it will mean its sucking air in....
just some things to think about


Cheers

[tandanus]

Why 2-stroke oil in the tank? OK, showing my age here. Years back, like late 1960s, the best thing for loosening up deposits was 2-stroke oil - the servo I worked in also sold it as "Upper cylinder lubricant" but it was just 2-stroke oil. We put it down the plug-'ole or for a gentler efffect we put it in the petrol. I have no idea what was in it, but it "fixed" many clapped-out bangers. There's probably some new-fangled concoction that does the same thing and costs twice the price now
T.

[81pw]

yeas its got new head and pistons, new spark plugs. does it when cold or hot. still does it if i drive it for 10 minutes or hour. ive tried everything. starts cold or hot everytime fine.

[DanTurboLancer]

Why 2-stroke oil in the tank? OK, showing my age here. Years back, like late 1960s, the best thing for loosening up deposits was 2-stroke oil - the servo I worked in also sold it as "Upper cylinder lubricant" but it was just 2-stroke oil. We put it down the plug-'ole or for a gentler efffect we put it in the petrol. I have no idea what was in it, but it "fixed" many clapped-out bangers. There's probably some new-fangled concoction that does the same thing and costs twice the price now
T.

Haha some times the older tricks work the best....
You're probly right, same stuff bottled by Lucas or what ever and charging $18 a 250ml bottle LOL

[81GL]

Have to remember that one T.

Interesting how it happens hot & cold, so its more or less guaranteed that it will run on for a bit once turned off?

As Crystalmeths pointed out, how lean is your idle mix running? make it a bit richer & see what effect it has (take not of there the screw is before hand)

Nick.

[davetrees]

Best way to check Vac leak for the inlet side of things isnt always the soapy water, try spraying Petrol, if revs pick up it will mean its sucking air in....

... or alternatively (if you don't want to blow yourself up ! ) use some Aerostart / "Start ya Bastard"

[81GL]

Best way to check Vac leak for the inlet side of things isnt always the soapy water, try spraying Petrol, if revs pick up it will mean its sucking air in....

... or alternatively (if you don't want to blow yourself up ! ) use some Aerostart / "Start ya Bastard"

Could help you by spraying the petrol... If things go pear shaped maybe it was an electrically related problem

...OF coarse... don't do it.

[DanTurboLancer]

I used to be a mechanic and thats what we used to do!

its only a fine mist and if it catches fire will run out pretty quick.....
Or you get an engine bay Paint job, either way lol

[Sigmaproject]

are the plugs the right heat range

[81GL]

are the plugs the right heat range

;) Bit of wisdom showing through there sigmaproject

-Plug should be a BP6E_ (insert what ever takes your fancy... S/Y/R ...)

Nick.

[81pw]

yea they are the right plugs. if anything its running bit rich.

[81pw]

just put i engine analizer when cold runs normal but when it reaches normal temp runs heaps lean but when i try change the air fuel adjuster does shit all besides make it leaner. i thinks its time for a new car.

[81GL]

You said you swapped out another carby in your first post yeah? so technically we can rule out a blocked jet or the likes (check anyway, its only a couple Philips screws lol)

So the car does drive fine when running? as you accelerator is doesn't feel hesitant?
Is it happy to maintain half/full throttle?

Just out of curiosity, what engine speed does it idle at?

Nick.

[81pw]

yea ive swapped 3 carbys now. still does it. when running runs fine idles at 850. timming at 7 btdc. revs to 5500rpm with no worrys. float levels right. taking it to a mates place to put it on the engine analizer again to retune it.

[81GL]

Let us know how you get on.

Its got me intrigued

[81pw]

yea we tuned yesterday i think it made it worse. we got it as 14.7 and CO to about 1.2% but now when i shift into 3rd gear car hops and splatters goes like 10km/h. so im really having bad luck with theses carbys or the engines just farked. im gonna swap over another intake manifold put all new vacuum lines on it. ive checked it million times for vacuum leaks but thats the only thing i can think of. ive notice after we turned it the engine only runs on when hot. turns straight off when cold.

[davetrees]

Just a random thought .... is the distributor OK ? Advance weights not stuck or anything ?

It can't be the carb, if you have swapped 3 of them with the same result (unless they all have the same problem, which seems an unlikely coincidence).

Is the ignition actually switching off properly ?

[tandanus]

Some more guesses...
If its OK when cold, but not when hot perhaps there's something weird about the automatic choke, although I guess that was swapped over with the carbs... Have you tried running it without that little electric valve that draws fresh air int when the ignition is turned off? ie block the tube off and unplug the valve?
When the motor was rebuilt, did you alter the compression ratio? What does the compression read as?
Fuel filter clear? Fuel pump delivering properly? Tappets adjusted correctly?
You can tell if the engine's farked by doing a leak-down test.
T.

[stealth]

or did old mate that rebuilt your engine leave a burr on one of the
combustion chamber? may be a thin as valve face?
all these things add to the problem what comp are you running?
cheers stealth

[81pw]

no i rebuilt the motor she was all good. comp ratio is standard 4g54 ratio 8.2 or sumthing. pulled carby apart last night cleaned it out. car turns off every go now. now i have this other problem. car dies in the ass when i change in to 3rd gear hops and jumps and splatters. i must say theres sigma carbys gotta be the crappest things ever made.lol

[81GL]

Being fair... they are getting to be rather old... diaphrams will be on their last legs for sure if they have never been replaced.

Time to pull it apart & give it another clean by the sounds ;)