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View Full Version : carb flooding when I start the car



Greg
10-22-2002, 08:22 AM
OK, I know that figuring this out might be a pain in the ass, but I need some help.

I was having problems with my idle staying too high after the car warmed up. Basically, the choke opener diaphram was leaking, and it wouldn't pull open the choke. I think my thermovalve A was also bad (I ran some tests on it with a hand pump, and it wouldn't hold vacuum from line 18 when the car was off).

I'm really broke, and so I didn't want to go get the oem parts to fix all this stuff. I also didn't want to get a dozen carbs from junkyards hoping to get good parts. I think there might be other problems with my carb as well, and I wanted a simple fix.

So I ran a cable to where the choke opener arm goes and created a manual choke. I think my manual choke is working fine as far as being able to pull open the choke a little extra once it warms up, and it seems to also retract fine when I push it back.

I basically left the automatic choke intact, using the spring action from the bimetal spring in the automatic choke as my return spring for the choke opener cable (does this make sense?)

I cut the arm from the choke opener diaphram that was broken and hooked the cable to this arm. So the cable pulls what the choke opener was pulling before.


Here is my problem:

On a cold morning, I push down the gas pedal to the floor twice and then start the car. It now gets WAY TOO MUCH GAS for some reason. It starts up, idles at about 2000 rpm (normal) for a second, and then drops down to 1500 and sounds REALLY crappy and smells like it's getting flooded with gas. When I look down the throat of the carb barrel, I see it spraying gas like a kid after a can of beans.

When I use my manual choke opener to open the choke, the idle surges to like 2500 for a while. This morning, after a little bit, it dropped down and stopped running rich after just a minute or less, and then I closed the choke mostly. THen it idled @ about 1800 or so (normal), and then when it warmed up, I pulled off the choke, kicked down the gas, and it went down to a smooth 900.

It always runs fine after the first couple minutes, but it is doing this erratic shit, spraying too much gas upstream of the throttle plate when I first start it.

WHY THE HELL IS IT DOING THIS?

Right now I have the vacuum lines from the old choke opener unplugged.

*** Here is some additional info.

Before, my line 14 to the top fitting on the back of the carb was cooked, and it had a big hole. I also replaced this line when I did my manual choke.

My crankcase breather element was totally clogged, and I changed this as well.

I washed down all my linkage, the choke plate, and the shit down the throat of the carb with a lot of carb cleaner.

I also did some poking around when I was checking out the carb, trying to gently push and pull linkage to make sure that nothing was stuck. I have this weird fear that maybe I pushed the arm to some diaphram and punctured some diaphram, but I don't really think I was rough with it.

I don't think I have any other vacuum leaks unless they are at the very bottom of the carb or underneath where I can't really see, but I really don't think so.

Do you think that reconnecting #14 (power valve) might be doing this? How does the power valve actually work? Does it just spray extra gas down the main metering jet in the main venturi upstream of the throttle plate?

Thanks so much for any help you can give me!!! I don't really have money, so I want to do cheap fixes if I can. I DON'T WANT to rebuild my carb. I don't have the time right now, I don't have a garage, and it's getting goddamn cold working on the street in Chicago.

Dutchboy
10-22-2002, 08:30 AM
WHOA...long post

anyway once A20A1 is on or other carb gods come on they can tell you what to plug and what not too...

just make sure that you plug the lines good so there isnt a vaccuum leak ...

and when starting it try not hitting the gas at all or mabye a bit to set the choke....its cold here too now and i only ever hit the gas just a bit and it starts right away....it will run shitty when its cold and has too much gas so try otherwise...

so im guessing that after it warms up it runs fine????
if so then theres probably nothing wrong except that one of those lines might needd to be plugged back in.....

Wait for the Gods...
BEn

Greg
10-22-2002, 08:37 AM
I tried plugging the vacuum lines to the choke opener (18 and 26 I think), and I also tried running 18 to the fitting on 26 (thereby joining the lines), and it seemed to be extra gassy when I did this, so I opened them up for now.

Yes, the car runs totally fine when warmed up. The idle is fine, the power is fine. Nothing weird.

I too think that it's probably mostly ok, but I don't understand why it gets so much gas when I start it.

I have been pushing the pedal down to the floor twice before I start it to close the choke and I guess this also pumps a little gas into the throat of the carb (I'm not sure exactly where it goes or how this works?)

Does anyone know if 2 pumps is too much? Could this be creating pressure that would make it keep spitting gas for a whole minute?

Should I just kick it a little bit to close the choke and then try to start it?

Dutchboy
10-22-2002, 12:04 PM
one push will close the choke....
like i said...i dont even kick it all the way once...and mine starts fine.
if it gets too much gas when cold itll run rough until it burns it off or gets pushed out the exhaust..

otherwise the accelerator pump could be stuck??
mmm,,,,wait for mike...hes a carb noitall

BEn

DanG86LX
10-22-2002, 02:25 PM
I don't see where ur problem is since the engine rpms look normal. If u feel that u get too much gas, just open the choke sooner. Cold starts are very, very rich, otherwise engine will stall.
First the fast idle cam sets to the highest step out of 3 (when u push the pedal b4 starting engine). The cam keeps the throttle open (for like 3000rpm when warm) and therefore vacuum is applied to venturi and that's what u saw:
"When I look down the throat of the carb barrel, I see it spraying gas like a kid after a can of beans."
It might be that ur power valve is stuck open (since #14 was broken = vacuum leak = power valve was open all the time ). Vacuum on #14 causes a plunger to retract which allows power valve to close. If it closes or remains open depends on its internal spring. Let's say is stuck open, then an internal fuel passage is open from bowl to venturi beside the normal jet passage, therefore more gas would reach venturi... but that's just a theory, to check it, u have to open the carb top and look down the float bowl ...

1. Your choke heater is faulty or there is no current going to it. Then the choke won't open during startup (but it might open after 20..30mts when heat from engine gets to it).. But u did ur manual choke which is good. How u operate it is a different story, cause u basically have to do what the choke opener will do.. i.e. start engine with flap closed, after 2..5sec open flap ~30*, then after 1 min. open flap ~ 45* (when line #18 would otherwise get vacuum), then gradually open the flap to vertical within 5mts. And everything should be stretched/shorten according to outside temps. Uh.. that' why an automatic choke system would be better.
2. Your thermovalve is probably OK, should be open below 15C (60F), and hold vacuum above.
3. Your choke opener was probably OK but u cut it. It shouldn't hold vacuum on #18 and #26 orifices since it get vacuum from internal passages under the throttle. That's why u should plug them, otherwise u got a vacuum leak. BTW, between the two, there is an internal bleed valve inside choke opener!
4. U should keep line #18 between choke opener and fast idle unloader ON, to enable unloader.

Hope this helps.

shepherd79
10-22-2002, 04:35 PM
i think your problem is that your carb is too old. and the parts need to be replaced and cleaned.
i would recomend go to autoparts store and pick up a rebuild kit. I got mine from autozone for like $25-30 or something like that.
take out the carb, take it a part, clean and rebuild. it did miracles on mine.
it is all i have to say. may be mike would have something better to say.

Greg
10-22-2002, 04:55 PM
My real problem is that my car is getting too much gas, it is running too rich.

I got the same symptoms this evening after not driving since 9am, and it has been plenty cold in CHicago. This is what happens:

When I have the choke closed when the car starts, it runs @ like 1500 RPM and runs like shit. It's getting way too much gas -- I can smell it. If I OPEN my choke at this point, it surges to 2500 RPM. After say 5min, when I test retracting my auto choke, it runs @ like 4000 RPM. At this point, it is warm enough for the air-fuel mixture to vaporize and if I let the choke retract to partial then it isn't getting enough air, and then it runs @ 2500 -- again, this is with a very open choke!

2500 is NOT normal with an open choke @ idle after 15 minutes of the car running.

Now, after about 20 min of warming up, it dropped down to 1000.

***
"3. Your choke opener was probably OK but u cut it. It shouldn't hold vacuum on #18 and #26 orifices since it get vacuum from internal passages under the throttle. That's why u should plug them, otherwise u got a vacuum leak. BTW, between the two, there is an internal bleed valve inside choke opener!
4. U should keep line #18 between choke opener and fast idle unloader ON, to enable unloader."
***

OK, I'm a dumbass :banghead: ; I didn't know that the opener got vacuum from internal passages under the throttle. I thought that it only got vacuum from 18 and 26. This is how I interpreted my Chilton's book (but relying on Chilton's for this stuff is probably a mistake in itself). I think Chilton's also said that Thermovalve A should hold vacuum when cold but should not when warm. I guess this is wrong huh?

I will try connecting 18 and 26 back to the choke opener and seeing if this does something. If not, I'll screw around with plugging 26 @ the opener and keeping 18 intact.

Maybe I'm getting a vacuum leak because this is open and that is causing the problem??? But I'm sure that I'm now getting too much gas.

My problem is that my ignorant ass :confused: didn't know that there was a vacuum source under the opener, and therefore I assumed that the diaphram leaked because I couldn't get the thing to pull when I drew a vacuum on 18 while 26 was plugged with the car off.

:banghead:

Well, I'll try this stuff. Thanks!

Greg
10-23-2002, 12:17 AM
Hey Dan,

You know, I'm being a total bonehead. You're totally right. I am probably not getting too much gas. I guess the choke opener has a stop @ about 45 degrees, and that's as far as my manual choke is going because I attached it to the choke opener arm.

That's why I'm still getting 2500 RPM or so but down to 1000 after like 25 minutes. You're probably absolutely right that my choke heater is not working and that's why it functions fine when the ambient heat from the engine finally relaxes the bimetal spring.

I thought that there was something that reduced the gas supply to the venturi when it warmed up, but I wasn't understanding the way it is supposed to work well enough.

I guess the choke opener probably engages pretty soon on a cold start to open the choke to 45 degrees, and the car has a 2000+ idle even then. I thought that when the choke opener finally engaged it would open the choke enough to bring the idle down to a normal operating idle.


Well, I think that at this point my best bet is to screw around with rigging my manual choke opener directly to the choke cam (or whatever you call it) and not the pin that the choke opener attaches to so I can open it manually past 45degrees.

I'm going to reconnect 18 and 26 (I'm hoping that there won't be a vacuum leak problem in the old choke opener now that it has a stump arm that doesn't stop at a certain point) and then adjust my manual choke. I'll see if this fixes things. Maybe I'll try to see if I'm getting power to the choke heater and then think about trying to find a good one @ a boneyard.


Hey, thanks again for your help!

DanG86LX
10-23-2002, 08:14 AM
Glad to hear u figure all out man.
Keep #18 between choke opener and fast idle unloader ON, and hook both orifices of fast idle unloader to it (provided they hold vacuum). maybe unloader is good so u don't need to do anything there. If #19 gets vacuum when engine warm, just leave it there. Just tap the gas to release the fast idle cam.
Remember this cam is set by some spring linkage by choke flap. If the choke is partially pulled, the cam will follow it and engage the appropriate cam step (out of 3 steps).

POS carb
10-23-2002, 02:16 PM
by cutting the choke opener arm you have caused a constant fast idle.

Greg
10-23-2002, 03:47 PM
How have I caused a constant fast idle if I hooked up a cable to the pin that the choke opener arm retracts, allowing me to retract it manually?

Wouldn't this do the exact same thing that the arm does, except I control it from inside the car? :confused:

Also, when the bimetal spring in the auto choke heats up from engine heat, doesn't it retract anyway?

My car DOES return to about 1000 idle after 25 min?


Anyway, I'm thinking about brazing or jbwelding the arm back together and linking my hand-choke cable directly to the choke-plate linkage to allow me to have force against the action of the bimetal spring to unload it before the thing warms up from engine heat.

But it's been raining here in Chicago and it gets dark at around 6:20PM (I get home from work @ 6) so I will probably have to wait until Saturday.

-Greg