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Discussion Starter #1
1963 Ford 390 won’t stay running. New rebuilt carburetor, starts right up but won’t stay running unless I’m pumping on the gas. Any ideas where to start? I’ve adjusted the fuel air mixture screws, took off the the after market fuel filter and changed fuel lines. Help please! Thanks
 

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Re: 390 won’t stay running

What intake, spacer, carb, distributor, where is the PCV tied in? When it does run, is it smooth? After it dies does it start right up? What is the wet float bowl level? When the engine is cold after a pump of gas how tightly closed is the choke? How did it run before?
 

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Discussion Starter #3
All original spacer, 4barrel carb, intake and dist. Manuel choke which is disconnected. PCv new. Cranks right up, doesn’t run smooth. Only runs if actively pumping throttle, dies at idle and if I just hold throttle steady. Had it running good and let it sit up for 2 months!!! Lesson learned....
 

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If it doesn’t run smooth it almost sounds like the timing is off. When I first cranked up my Pontiac after rebuild it was like that. Would run rough and die if you didn’t pedal baby it. I added a proper amount of advance and it ran fine.

Was it ever in time or is this a fresh rebuild? If it was timed well before and this is a new problem make sure the hold down bolt wasn’t loose allowing the distributor to turn.
 

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Discussion Starter #6
I had it running well. It was timed good idle. I have tried to reset the timing but it’s so hard to keep it running. What y’all thing about the fuel pump? Maybe letting it sit up messed that up? I’m lost, all vacuum hoses r new.
 

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If it needs pumping the throttle to keep it running it sounds like a dirty carb. Pumping the throttle gives you a shot of fuel from the accelerator pump, but steady throttle stalls. I think you need to disassemble the carbs and give it a good cleaning. Put the fuel filter back on, too. Will it run at at any steady throttle position? Get someone to run the ignition and look down the carb while you work the throttle with your hand. Watch and see where you have fuel emerging and entering the air stream.
 

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Re: 390 won’t stay running

have a helper start it . push the choke plate towards closed an see if you can get it to run by choking. if you can, - you have a fuel delivery problem. could be float level, dirt in jets, vacuum leak.
 

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I agree - sounds like a fuel issue. With the throttle open and the engine running, you should see fuel squirt when the throttle is opened and then dribbling out of the boosters once that's over. Can you see fuel vapour coming out of the annular boosters? (the round things on sticks in the middle of the venturi)
 

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Discussion Starter #11
So got it running w the choke closed. Once I open the choke it kills. When I pump the gas I see fuel coming out, think I will try to clean the carb.
 

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Re: 390 won’t stay running

So got it running w the choke closed. Once I open the choke it kills. When I pump the gas I see fuel coming out, think I will try to clean the carb.
This still points to a vacuum leak.
Hoses may be new, but are all vac ports plugged in/hooked to something?
 

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Discussion Starter #13
I will run through the vacuum lines and ports one last time make sure I’m not missing any thing before I take down carb.
 

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Discussion Starter #14
I will run through the vacuum lines and ports one last time make sure I’m not missing any thing before I take down carb.
 

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1.) If you don't use an original Ford intake the vacuum leak is under the spacer, in the back.
2.) Otherwise, if it idles ok with the choke closed, fix the choke.
 

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Re: 390 won’t stay running

I will run through the vacuum lines and ports one last time make sure I’m not missing any thing before I take down carb.
Also use your ears. :smile2:

When it's running, listen carefully for the tell-tale hissing sound of a vacuum leak.

It may be hard to hear over other engine noises,
but if the engine won't run unless the choke is closed,
it should be a fairly massive leak and easy to hear... if your ear is trained for it. :wink2:
 

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Discussion Starter #17
Yes think I found it but when I spray carb cleaner (not safe I know) it actually kills the engine, I thought it’s supposed to increase rpms? Seems to be right in the back of the carb spacer.
 

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Re: 390 won’t stay running

if you are holding the choke partialy closed to keep it running, adding fuel(carb cleaner) will make it too rich-causing flooding (stall)
 

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Re: 390 won’t stay running

Yeah, if you spray carb cleaner like that and get a change in engine speed up OR down/dying, it means the cleaner is getting sucked in, so vacuum leak.

Pat
 
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