Sputtering

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Mar 16, 2015 | 04:51 PM

69'er

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Sputtering

My '69 F-250 2bbl 390 has been sputtering on taking off. It does fine at an idle and when it isn't in gear. I overhauled the motor last year and installed a factory remanufactured Autolite 2 bbl carb that has never really seemed to be up to snuff. Dwell and timing are good and I've found no vacuum leaks or other indications I may have a leak. Accelerator pump maybe? Thanks for any suggestions!

Mar 16, 2015 | 11:21 PM

51M1

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Quote:

Originally Posted by 69'er

Possibly Accelerator pump linkage adjustment. I dont know if your carb has different holes for the linkage but if it does, try changing closer to the pump for more fuel, further away for less.

Mar 17, 2015 | 03:27 AM

69'er

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Thanks for the reply 51M1. The linkage does have different holes. I installed it by the specs so it is in the outboard hole now. I didn't know how it affected the pump but from what you've said it's worth trying it on the inboard side as it seems to need more fuel when it's under load.

Mar 17, 2015 | 01:09 PM

69'er

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Tried that and it didn't help. The power valve seems to be fine also. I'm stuck on thinking it's the accelerator valve. I may just try to replace it or put a whole new kit in it.

Mar 17, 2015 | 02:21 PM

Freightrain

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From: Ohio

Look carefully at the linkage. The accel pump is actuated by a spring wound around the throttle linkage arm. When you move the throttle, the wound spring is what pushes the accel pump arm. If that linkage gets sticky/gummed up, the spring will not push the accel pump quick enough and it will hesitate under load(in gear). Been there, done that. That is why I hate Autolite carbs. Put a couple shots of PB Blaster or such on it and see if it frees up and works better. You will then notice over time it starts hesitating. Keep it lubed. Did I mention I hate Autolite carbs because of this. In park, it gives it enough fuel to run great.

That spring is just not stout enough to work well over time.

Mar 17, 2015 | 08:07 PM

69'er

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Thanks for your reply Freightrain. I can see where that might be a problem and did spray it down with a lubricant but it didn't help. The carb has been recently factory overhauled so it's working well there. I've been driving this truck for 26-27 years now and never had that issue but we all come across them. I dread replacing starters.An easy enough job but hard to tell the parts house that their fifth starter is no good either! I did replace the accelerator valve and it didn't improve things much either. Still looking for the answer!

Mar 18, 2015 | 07:32 PM

JEFFFAFA

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From: Phoenix, Az.

Quote:

Originally Posted by 69'er

It prolly wasn't "just" factory rebuilt. If that carb had been rebuilt before our current oxygenated fuels and been sitting on a shelf ever since then I would say accelerator pump diaphragm is shot. The original rubber making those and fuel pump diaphragms can't hang with the new gas. Buy an aftermarket (gas friendly) version of C4AZ9B559A.