2F only starts and idles on choke (1 Viewer)

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Sounds like the Fuel Cut Solenoid (FCS) (aka ICS) to me too. Finding out is easy in theory, but be careful in practice. Bypass the entire Deceleration Fuel Cut System (shown in 1981 2F Emission Control Repair Manual, pg. 3-44) for this test by disconnecting FCS connector at carb and connecting 12v and ground jumpers to the two terminals on the FCS connector. Polarity doesn't matter, but BE CAREFUL not to touch the two jumpers to each other, they are close together. And, if using jumpers from truck battery, DON'T touch 12v jumper to the carb or obviously each other, it gets very exciting.

Better yet, make two short wires with female terminals on them to bring the male FCS connector terminals out of their housing and further from each other. Then hook up Pwr/Gnd jumpers--if FCS is working, you'll hear a 'click'. Start engine and see if behavior has changed/improved. An even more dramatic way to test is connecting those jumpers (brought out of the FCS housing) while engine is running, but that's DICEY to do with a running engine--do only if you're an experienced shade-tree. If the test result is the engine runs better (maybe with choke off now) with FCS jumpered to 'on', then the FCS is working properly. Now you have some Deceleration Fuel Cut System troubleshooting to do.

Jumper FCS.jpg
 
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Sounds like the Fuel Cut Solenoid (FCS) (aka ICS) to me too. Finding out is easy in theory, but be careful in practice. Bypass the entire Deceleration Fuel Cut System (shown in 1981 2F Emission Control Repair Manual, pg. 3-44) for this test by disconnecting FCS connector at carb and connecting 12v and ground jumpers to the two terminals on the FCS connector. Polarity doesn't matter, but BE CAREFUL not to touch the two jumpers to each other, they are close together. And, if using jumpers from truck battery, DON'T touch 12v jumper to the carb or obviously each other, it gets very exciting.

Better yet, make two short wires with female terminals on them to bring the male FCS connector terminals out of their housing and further from each other. Then hook up Pwr/Gnd jumpers--if FCS is working, you'll hear a 'click'. Start engine and see if behavior has changed/improved. An even more dramatic way to test is connecting those jumpers (brought out of the FCS housing) while engine is running, but that's DICEY to do with a running engine--do only if you're an experienced shade-tree. If the test result is the engine runs better (maybe with choke off now) with FCS jumpered to 'on', then the FCS is working properly. Now you have some Deceleration Fuel Cut System troubleshooting to do.

View attachment 2657410
Ok, thanks for the tip. I’ll give it a try. Thanks!
 
I once rebuilt a carb and afterward had a serious internal vacuum leak inside the carb resulting in only starting and and running with choke pulled and rpms really up. I had neglected to install a small part inside the carb and took me 3 times of pulling it off and going through it before I figured it out. Look around your work area, on the floor too, to see if a small part is laying around.

Just saying, missing an internal part can cause an internal vacuum leak. Best bet is to go step by step through the FSM carb rebuild procedure and make sure you didn't miss anything. Of course, check for external vacuum leaks first with carb cleaner spray and check the ICS by listening for the click when you turn the key on.
 
Now *that* was a helluva hard issue to resolve, first time I've heard of that particular symptom/resolution. Pack that one away in the bag of tricks.
 

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