Help me troubleshoot

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Dec 30, 2010 | 08:41 PM

dougmiller

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Help me troubleshoot

I have a 1976 F250 with a 460 motor. The truck sat for about ten years before I purchased it. I drove the truck about 200 miles home on the interstate and it ran fine at 60mph. When starting from a dead stop or after idling for a few seconds, there is a significant hesitation when trying to accelerate again. Since getting the truck home I have replaced the rubber fuel lines that were cracked, fuel pump, fuel filter on the front of the carburetor and the replaceable parts in the upper portion of the carburetor, including the accelerator pump diaphragm. Just before I purchased the truck, the owner said he had replaced the spark plugs and wires. With all that work done the truck still hesitates when accelerating from a stop. It does seem to run better when it is cold. Any ideas on what I should try next?

Dec 30, 2010 | 09:35 PM

Pickupmanx2

Lead Driver

Joined: Jun 2006

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From: Near Yosemite CA

Welcome to FTE dougmiller,,, congrats on your new dentside! How does it idle? is it rough,,, sounds like you have a vacuum leak, or your vacuum advance is not working,,, is your vacuum advance hooked to a ported source,,, that is where you get vauum upon opening the throttle,, or to manifold vacuum,,, which is a constant source at idle, but drops when throttle is blipped..
Again, welcome to FTE and we will get ya help!

Dec 30, 2010 | 10:09 PM

dougmiller

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Thanks for the reply and now the homework begins on the vacuum system. The truck has idled just fine despite any changes that I have made. My knowledge of auto maintenance is almost limited to changing wiper blades as I fumbled through what I have replaced. Are any of the vacuum lines that you mentioned attached to the carburetor and what is the best way to locate a leak. I'll study the manual and hopefully be able to answer some of your questions. Again, thanks for the help.

Dec 30, 2010 | 10:23 PM

OrangeJuice

More Turbo

Joined: Nov 2007

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From: Western Washington

I know this discussion was from a different engine family, but it still may be of help...

https://www.ford-trucks.com/forums/9...250-360-a.html

OJ

Dec 30, 2010 | 11:19 PM

dougmiller

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Quote:

Originally Posted by OrangeJuice

I know this discussion was from a different engine family, but it still may be of help...

https://www.ford-trucks.com/forums/9...250-360-a.html

OJ

From reading through the discussion I think I'll have to check on my accelerator pump diaphragm. The truck ran fine at first and then I got the bright idea to adjust the accelerator pump diaphragm stroke. I just assumed the truck started hesitating again because it got warm. It might be because I destroyed the new diaphragm.

Dec 31, 2010 | 08:30 AM

Joseph69

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Joined: May 2010

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The diaphragm could have a small crack in the rubber, when it warms up it gets softer and starts leaking more. Easy to replace while still on the engine.