Cold Starting -- to rich

[rgentry]

Cold Starting -- too rich

I recently installed a rebuilt 1-BBL carb on my '68 FJ40. When I crank
my cruiser on a really cold day, all I need is about 1/2 a pump on the
pedal and NO choke at all. The cruiser fires right up and then I have
to choke it to keep it running as it warms up. If I pump it more than
once, or choke it, it floods. I then have to let it sit for a while or push
the "pedal to the floor" while cranking to clear the gas out.

My question is: why is it so rich when I am cold cranking? Does this
mean that it is too rich when running regularly? I set the idle mixture
using a vacuum gage, and got around 18 inches of vacuum with very
little bounce (less than 1 inch). My distributor is a new 1968 vacuum
advance, and the timing at idle is advanced about 4 degrees past the
BB.

I have 4 or 5 of the old 1 barrel carbs in various states of disassembly.
Perhaps I overjetted this one when I rebuilt it. Could that make it run
rich?

 

[IDave]

I don't know the answer, but I can tell you that my large sight glass 1bbl F135 starts and runs the very same way. What kind of air cleaner do you have? I have wondered if my oil bath was (relatively) starving it for air (which would be exacerbated by living at 5150 feet above sealevel), and am going to try the paper filters setup I got from Marks Off Road.

 

[rgentry]

Stock paper aircleaner for the '68. I am in Atlanta at 1000 ft. above
sea level. I don't think that elevation plays any part in my problem.
I have the "small window" carb, without the step up rod. I am wondering
if my carb is letting gas "drip" into the intake from the bowl, thus putting
a lot of gas in the manifold when I start her up. No evidence of that though.

 

[skyshark186]

My 350 does the same. I just play it off on the engine being cold. Never have a problem with it when its warm, so im not gonna overanilyze it.

 

[65swb45]

I am sure that someone with a better understanding of physics would explain the atomization of fuel at different temperatures and inches of mercury, blah, blah, blah, but when all is said and done, remember that even brand new, tuned port injection vehicles have a separate circuit for warm up conditions [I think they call it closed loop vs open or visa versa] so the problem is definitely NOT landcruiser specific.

I use both the hand choke and hand throttle to start my 45dd and just enjoy being able to take off in the morning pretty much as soon as I start the truck. I have a permanently installed vacuum guage which tells me initial vacuum is barely 16, with the choke on, which helps explain the need.

 

[Pin_Head]

The colder it is, the more choke you need to get it started, so your description is pretty wierd.

Is it worse when the weather is warm? Should be. Is there a pool of gas at the botom of your intake before you stry to start it? If so, maybe the idle circuit is siphoning. The fuel bowl would be empty if you let it sit long enough. It isn't supposed to siphon, because there is an air vent that prevents siphoning, but it can get plugged. Later carbs also have an idle fuel cut off.

PS. I noticed that Mark Whatley said in the recent issue of TT that Aisin carbs can't leak because there is no fuel exit below the bowl level, but I think he forgot that the idle and slow jet ports are in the cast iron base right by the throttle butterfly.

 

[65swb45]

PS. I noticed that Mark Whatley said in the recent issue of TT that Aisin carbs can't leak because there is no fuel exit below the bowl level, but I think he forgot that the idle and slow jet ports are in the cast iron base right by the throttle butterfly.

An interesting point indeed. I wonder if the slo-jet could still siphon slowly with a properly functioning fuel shut-off solenoid.

 

[peesalot]

sounds to me like your vehicle is functioning like it should . If it starts and runs fine when warm and does not load up after you get it started cold then it is just the way it is. My 350 with old school carter is same exact way. Had to prop choke open and hold er to the floor even after just stopping for lunch. I would say if it starts every time by the details you said it is dialed in cause it does the same thing consistently. Best way to have it.
Can of starting fluid if it is really cold.
I wouldn't expect it to run good ice cold , do you ?

 

[critterhunter]

If I were you I would check your needle and set, if the needle is not stopping the fuel all the way it will load up your intake with fuel, then once it burns off you would have to choke it again.

 

[rgentry]

The colder it is, the more choke you need to get it started, so your description is pretty wierd.

Is it worse when the weather is warm? Should be. Is there a pool of gas at the botom of your intake before you stry to start it? If so, maybe the idle circuit is siphoning. The fuel bowl would be empty if you let it sit long enough. It isn't supposed to siphon, because there is an air vent that prevents siphoning, but it can get plugged. Later carbs also have an idle fuel cut off.
.

PH. When my cruiser is warm I start without touching anything. No pump of
the pedal, no choke. Once it's running I pull the choke out to get a bit of
a fast idle. My sense is that my cruiser runs much better when it's cold or
cool, and "might" be over-rich when it's finally warmed up. It certainly
seems to idle better when it's warm.

As for a potential carb leak, I cannot tell if the fuel level has dropped in the
window, even if my cruiser has not been run for a week+. So, I guess if
it's leaking it's not much. I do have a functioning (at least "clicking") idle
solenoid.

 

[rgentry]

I am wondering
if my carb is letting gas "drip" into the intake from the bowl, thus putting
a lot of gas in the manifold when I start her up. No evidence of that though.

BINGO. Carb was empty this morning. Gas must be dripping into the
intake somehow. Seems like PH is correct and gas can get out
somehow. But how? Will this lead to engine damage?