Choke Question?

Choke Question?
phinleft

phinleft

Jeeper
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Location
Baton Rouge, LA
Vehicle(s)
78 CJ7, Amc 304 V8 - AMC 20, DANA 30, Quadratra Trac TH400, 35" Mickey Thompsons MTZPainted LSU Yellow/Gold. Modified with 4bl Edelbrock Carb.
Choke plate is closed before starting. I thought after 5-10 min of running it would open fully once warm. The plate only opens 2-3 inches. If I open it more, the engine kills. Any ideas, what is the cause? After running it for 30 minutes the choke plate will open about half, and the engine will die. If I adjust it manually and slightly close it. The engine runs great again.

Would adjusting the air/fuel adjustment make any difference.

Stock carter carb with a coil thermostat, which is ok.
 
If the engine runs better with the choke on, you have a vacuum leak. This only applies if the engine is at operating temperatures. Break out the carb cleaner and hose down the carb base and the intake gasket.
 
priceg said:
If the engine runs better with the choke on, you have a vacuum leak. This only applies if the engine is at operating temperatures. Break out the carb cleaner and hose down the carb base and the intake gasket.
Click to expand...

X2 :chug:
 
I will get to it. Thanks
 
I hosed it down, like you said. Waited for it to get warm. Doesn't seem to suck it in around the carb base. When I spray the intake connection where the seal is, it seems to evaporate in places. Could that be due to the heat of the engine? If I replace the intake seal, is there something I need to know first? Does the intake manifold and exhaust manifold all need to come off at once? What other areas could cause vacuum leaks? I have replace cracked hoses, except the distributor hose. Could do it since it is cheap.Any other places, that I could check for leaks? I can run the engine and drive. I would understand, that what you are all saying is, that the choke isn't opening all the way, because it is drawing plenty of air somewhere else? Thanks for all your help.
 
Just on the odd chance you are not familiar with looking for vacuum leaks with carb cleaner. While the engine is warm and running, very sparingly spray cleaner at the gasket joints of the carb and intake. When a vacuum leak is present the RPM of the motor will increase noticeably . This will help Identify where there is a need to tighten some fasternrs.:cool:
 
Thanks IO. I am not experienced with looking for leaks on the intake manifold. I will do it again and listen for different sounds in the engine. Is the carb cleaner to flammable, that I should be concerned?
 
It is most definitely flammable, that is how it works when it gets sucked into the leak.
Do be careful , there is no reason to deliberately spray carb cleaner on the exhaust manifold, just the joint between the intake and the head and the carb to manifold and , of course the joints between the parts of the carb. do just a little area at a time so you can zero in on the leak. fire extinguisher.

phinleft said:
Thanks IO. I am not experienced with looking for leaks on the intake manifold. I will do it again and listen for different sounds in the engine. Is the carb cleaner to flammable, that I should be concerned?
Click to expand...
 
avoid exhaust manifold unless you want a bbq.gif:chug:
 
I have sprayed every conection place on the intake, and carb. No difference in the sound of the engine. Where do I look next? I wnat to bang my head against the wall. :bang: I have changed all the hoses on the carb and egr valve. Would the egr valve cause this problem?
 
I am hesitant to say this but is it possible the mixture screws are leaned out to the point that it needs choke to run?? I'm looking for other opinions on this.:cool:
 
On a bbd the metering screws should be between 1.5 to 2 turns out. Their is a possibility that the metering rod well is stopped up and choking it is forcing engine vacuum to pull the fuel past the rods to the main jets. Kind of like a stopped up pilot jet. Its tough to speculate.
 
Should I screw the mix screw in all the way, and back it out two full turns? At this point, I am willing to try anything. Taking the jeep to a mechanic is my last option, because I am trying to keep a tight monthly budget. I will do it if I can't come up with anything else.
 
Go ahead and remove them and spray some carb cleaner in the ports, then reinstall them. Screw themin untill they stop, do not force them in or you will bend the tips. Then back them out 2 turns. At least you will know that setting is correct.
 
When you refer to "them". I want to make sure you are talking about the air/fuel mix screw and the ide screw, correct? Want to make sure we are on the same page.
 
correct.Carters actual name for them is Idle Adjusting Needles
 
You all are very helpful! Thanks!
 
 
You have a YF. Unplug the line next to the fuel line. that is a bowl vent and needs to be open to atmosphere.
 
Why would the PO have plugged it?
 
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