Manual choke removal.
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Joined: Apr 2014
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Manual choke removal.
I bought a 1983 f150 short bed 4x4, it would only run with the choke pulled open. The guy promised me that it was just cold natured and after it warmed up ...be just fine. I drove it home almost 20 miles with it choked . It would try to cut out and die if I opened it. So as I'm driving down the highway I could open the choke. But at a stop light I had to pull it (choke it) so the very second I got home it dies in the drive way. Literally. Since then I've replaced a gas tank,the old one was rust filled, the fuel pump, and I removed the manual choke. I know I probably screwed up. But now I can seem to get the timing right or the carb adjusted right. I had it idel good at one time but as I drove down the road it cut out somthing bad. So I think I've adjusted my self into a mess. Please help were to start. I just replaced spark plugs this morning. Step one ....step two...?
Senior User
Joined: Dec 2013
Posts: 348
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From: Bakersfield,CA
Get a vacuum gauge and connect it to a manifold vacuum source below the carburetor throttle plate.
Log onto U-Tube and search for the video "vacuum gauge". There is a realy good video describing ten different engine condition symptoms using a simple vacuum gauge.
My guess , the engine has an intake manifold leak indicated by a low vacuum reading, 3-10 in Hg pressure below atmosphere pressure. Normal is 17-21 in Hg at idle engine speed.
By choking the engine, the manifold vacuum increases from the restriction of the choke plate which compensates for an intake manifold leak.
Log onto U-Tube and search for the video "vacuum gauge". There is a realy good video describing ten different engine condition symptoms using a simple vacuum gauge.
My guess , the engine has an intake manifold leak indicated by a low vacuum reading, 3-10 in Hg pressure below atmosphere pressure. Normal is 17-21 in Hg at idle engine speed.
By choking the engine, the manifold vacuum increases from the restriction of the choke plate which compensates for an intake manifold leak.
Lead Driver
Joined: Jul 2009
Posts: 6,477
Likes: 19
From: Sheffield, AL
These engines hate vacuum leaks. Check all vacuum lines looking for cracks, missing lines or uncapped ports on the carburetor or vacuum trees [on the intake manifold where several vacuum lines share a fitting].
Vacuum leaks can occur at the master cylinder power booster of PCV valve. Check the two nuts which hold down the carburetor as they vibrate loose. Take the air cleaner in your hands and gently rock from side to side. If it moves [while mounted to the carburetor], then either the two bolts are loose or the 4 screws which hold the two carburetor halves together are loose, which causes vacuum leaks.
Also, with the engine idling, spray carburetor cleaner where the intake manifold meets the engine block. If the idle speed changes, you have discovered a leak.
I would replace the choke as you will need it on cool mornings. Where are you located?
Vacuum leaks can occur at the master cylinder power booster of PCV valve. Check the two nuts which hold down the carburetor as they vibrate loose. Take the air cleaner in your hands and gently rock from side to side. If it moves [while mounted to the carburetor], then either the two bolts are loose or the 4 screws which hold the two carburetor halves together are loose, which causes vacuum leaks.
Also, with the engine idling, spray carburetor cleaner where the intake manifold meets the engine block. If the idle speed changes, you have discovered a leak.
I would replace the choke as you will need it on cool mornings. Where are you located?
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I live in springfield mo. Yeah there is quite a few places were I assume lines should be. The egr valve is not hooked up. There is a tree with four male fittings (black plastic) right by the theremostate housing that has nothing hooked up to it. I'm gonna find an auto choke to put on it. And see if orileys has a vaccum line kit.
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