4Y Hard to start cold carby empty why ?

[qbucket]

Hi , Any one know why my ASIAN carbys float bowl emptys it self over night after a hot run ? Fitted to 4Y . Have tried a new carby and kitted original one . Still the same trouble . Just wont start cold, electric choke works ok . Rest of engine is ok . I beleive this is a common fault ? Does any one have an answer . I want to keep the standard carby .

Thanks qbucket.

[oldcorollas]

leakingout the bottom? has very low float level to begin with?
seems unlikely that the carby is getting so hot, and so much heatsoak after stopping, that all the fuel evaporates (but stranger things do happen)

[qbucket]

Hi Oldcorolla , The float level is ok , inline with dod on sight glass.
No external leaks .
The fuel some how leaks into the manifold ? Pressure build up in float chamber ?
I dont think its too hot , has insuator block between carby and manifold .
I have seen this question asked on the net before on a US site but no answer given.
My mate fitted 180 Holley to over come this problem .
I want to keep mine stock .

Thanks for your reply Mate !!!
is that your car ?

[oldcorollas]

not my car but i wish. is a canadian car.

hmm.the float chamber should be open to the air cleaner pressure, via the tubes at the top above the venturies (tube poking up under the washer numbered 36 in this diagram http://www.carburetorfactory.com/expvw28.html ) so unless those tubes are blocked, there should be no extra air pressure int he float chamber.

if the fuel level is at the mark during running and after you turn off car, then it is a bit odd.

can you check that when you turn off, that the level int he float chamber doesn't rise? ie, if the float needle valve isn't 100% sealing, the fuel pressure in the lines might be enough to slowly squeeze fuel into the float chamber and then it actualyl overflows into the manifold, making it hard to start?
ie, when you go to cold start and can't see fuel level, it is actually full, not empty?
i guess the way to check that is to watch the sight glass when starting when cold.. and then see if the level decreases from the top, or increases from the bottom.

before that tho. if you pump accelerator when cold, does fuel squirt into the throats? if so, you have fuel. if not, it might be dry (or dead pump etc).
does pumping accelerator make it easier or harder to start?
does not pumping at all, and then holding throttle open make it easier to start?

other issues.. maybe either fuel pump is not makign enough pressure.. or making too much pressure?

[qbucket]

Thanks oldcoralla . When the car is cold ( left over night ) the float chamber apears empty , you can not see any fuel in the sight glass.
To start the engine now i have to wind it over for a fair while to fill up the carby , and pump the throttle a lot before it will fire up .( nearly flatens the battery ).
I would say the vent tubes are not blocked .
The float needle valve is ok .Fuel pump should be ok it has a return line to tank on it 3 hoses.
Leave it with me for a while and i will check my accelerator pumps operation ( squirting fuel ) . And see if the fuel is sitting in the manifold .
You are asking me if its flooded or no fuel making it hard to start ?
I will do as you say and experment with the throtle position.
I will check my electric choke again .
Some times i may not start the car for a week.
I may even try a different carby.
But i would still like to know how the float chamber drains ( siphening?).
I do understand what you are saying, sounds like you know about carbys.
I will get back to you.

Thanks qbucket

[oldcorollas]

You are asking me if its flooded or no fuel making it hard to start ?
I will do as you say and experment with the throtle position.
I will check my electric choke again .
Some times i may not start the car for a week.
I may even try a different carby.
But i would still like to know how the float chamber drains ( siphening?).
I do understand what you are saying, sounds like you know about carbys.
I will get back to you.

Thanks qbucket

yup, thats what i wanna know
are you sure you can see no fuel in the sight glass? or you can see no line because it is too full? (i guess with torch, you can see if there is colour or not etc? )
i am not sure how it could drain.
some carbs have a solenoid that cuts off the fuel to the idle jet when ign turns off, but even with no solenoid, it seems unusual for the fuel to leak thru the idle jet to drain the fuel bowl.

there are no fuel stains aroudn the carb?
is it unusually hot in your area? if really hot, fuel can evaporate out of the bowl over time. similar to vapour lock in fuel lines.

do you happen to have an electric fuel pump lying around?
if so, then you can hook it up to turn on with IGN.. then let it run for a few seconds as it fills the fuel bowl, and then start car...
masks the problem, but might make life easier.

[qbucket]

Thanks oldcorollas

Electric fuel pump , good idea .
Save draining my battery and cooking the starter.
How would i hose it ?
I would like to use it for cold starting only and run a seperate switch.

qbucket

[oldcorollas]

thats a neat idea but you could just replace the mec pump totally too
if elec alone, usually it is place near the fuel tank or in/under the boot, so it doesn't have to suck fuel too hard.

if you put the elec in series with the mech, sometimes the mech will stop in a position that the elec pump can't force furl thru.. so won't work., and chances are, the mech pump can7t suck fuel through the elec pump if it is off.. so...

you could place the elec pump parallel to the mech pump, but you will likely need a 1 way valve after the elec pump, so the mech pump doesn't force fuel back through it, or damage it in any way.. that way you are just pumping fuel around the mech pump when it is off.
you could either mount the elec pump on the block under the mech pump, or nearby on a panel (which means longer hosing and if engine shakes around, so will hoses)

depending on position of carby and hose from back of car, you could put elec pump elsewhere, but it is a godo idea to keep the pump low, so that it doesn't have to generate suction to pull fuel upwards. ie, at level of tank or lower (if possible).

[JZA70R_92]

Upgrade to a 32/36 Weber carb using a redline adaptor..Picking mine up this arvo...cost me $60 will post up results! 32/36 = easy carby to rebuild(did it myself) very simple to use hell even the throttle linkage bolts up to the weber. My issue is cold start choke never works even after replacing choke and the 2nd barrel doesnt open. My car sat outside yesterday at work in 38 deg heat and no sign of evap. started 1st turn after 2 pumps of throttle.

btw I have a spare 4Y carby in working condion(float bowl full of fuel) if you need one only missing 1 part.....

[oldcorollas]

is second barrel vac opening? or mechanical opening?
was choke adjusted properly, or getting power?

[JZA70R_92]

YES AND YES lol regardless weber is going on dont need all that complitacted crap to run the car

[JZA70R_92]

Installed 32/36 Weber last night to “test” she fits in place using original throttle bracket and linkage was attached in place on Weber. Though auto choke housing had to be removed may look into good old manual choke easy enough. It ran ok took awhile to start due to carbie needing a kit put through it ASAP! Acc pump diaphragm has hardened up so doesn’t pump! Overall it ran ok sounded way different.. hope to install kit tonight and see if she can idle and test drive.