hesitation problem

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Nov 28, 2007 | 04:28 PM

bigdavevader

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hesitation problem

Hi all, just bought an 82 f-150 Lariat with a carbed 302. It has a rough idle and a hesitation or stumble on acceleration. If I give it more throttle it smooths out. When going down the road it will cruise fine,but if you slow down or let off the gas it stumbles. Haven't done much to it yet,checked plugs,cap,rotor,some vacuum lines,and haven't gotten it right. Please help identify some probable causes.thanks

Nov 28, 2007 | 05:17 PM

Franklin2

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From: Virginia

Well, the stumble on acceleration sounds like the accelerator pump is not working correctly in the carb. But if we assume a single problem is causing both accel and decel symptoms, my first guess would be the wiring going to the pick-up in inside the dist. The dist plate moves on acceleration and deceleration, so if one of those wires going to the pick-up was broken inside, it could cause it to miss.

Nov 28, 2007 | 05:23 PM

kc5gxl

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Howdy BigDave;

Welcome to the group! There are several things that could cause a rough idle and stumble or hesitation on accel. Wrong ignition timing, bad timing chain, incorrectly adjusted idle mixture screws, bad accelerator pump, bad power valve in carb, stuck open egr valve, and I am sure a lot more.

Is the carb a VV or regular 2150 2bbl?

I would start by checking the timing and adjusting the carb. Make sure the plug wires are in the correct firing order. If that isn't the problem, then deeper investigation is necessary. You started out right, doing the easy things first. Keep going like that. You will eventually find the culprit.

Good luck and let us know what you find out.

Dan Harriman 84 F150 lwb
Orange, Texas

Nov 28, 2007 | 07:57 PM

Harte3

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From: Spokane, WA

An '82? If the Cat or EGR have not ever been replaced there is a good chance either one or both could be the problem.

Nov 30, 2007 | 01:05 PM

fairfield86f150

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i had the exact same problem with hesitation on my 351w. i solved the issue by buying a accelorator pump cam kit, and then i just experimented with the different size cams.....i ended up using the white cam, instead of the green one that was on the carb.

Dec 13, 2007 | 01:52 PM

bigdavevader

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follow up

Hey guys, just wanted to post a little update. I found the carb base gasket was cracked and leaking severely. Replaced stack of gaskets and spacers,runs little better,still stumbles on acceleration. How can I tell which carb I have? All the numbers I found were 25 Motorcraft on top left, and 1.02 or 1.08 on the right side. Ialso have no fast idle and the choke stays open. Anymore info is appreciated.

Dec 13, 2007 | 10:23 PM

Franklin2

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From: Virginia

You probably have a motorcraft 2bbl. What is this "stack of gaskets"? You should have one on the manifold, a spacer, and then one under the carb. If you have gaskets "stacked", then that's bad news because it will warp the bottom of the carb when you tighten it down.

Go to this site, http://www.carburetorfactory.com/index.html, and see if you can find a carb in the illustrations that looks like yours.