Hesitation from stop
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Hesitation from stop
My 84 Bronco with a 302 has a hesitation I have not been able to diagnose. I had the 2 barrel carb rebuilt by Ford and just replaced the vacuum advance. It runs great at idle and once moving. I suspect it is vacuum related. Anyone else have a similar issue? It has all the original emission control intact. I'm bringing it home this weekend to replace the exhaust and want to get this fixed also. Thanks!
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From: Boise, Idaho
Do you know what type of carburetor it is? (Exact model and number).
It sounds like it may not be getting enough fuel right off the bat, which is generally controlled by an accelerator pump.
If you take the air cleaner off and move the throttle, you should see some form of fuel squirt down into the throttle bores. If not, I suspect it's hesitating due to running lean.
It sounds like it may not be getting enough fuel right off the bat, which is generally controlled by an accelerator pump.
If you take the air cleaner off and move the throttle, you should see some form of fuel squirt down into the throttle bores. If not, I suspect it's hesitating due to running lean.
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Joined: Sep 2002
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From: Gateway to the West
The OEM two-barrel in '84 was still the Autolite 2100 wasn't it?
My memory could be rusty there but no matter which carb is on the truck, the idle speed, idle mixture (if applicable... some carbs had cast plugs over the mixture screws presumably because they "never need adjustment" HA!) and choke pull-off settings will still have to be set with the carb ON the truck.
IF the carb is indeed an Autolite 2100 or Motorcraft 2150 this is a pretty good write-up on the rebuild and adjustments including the on-car adjustments.
My memory could be rusty there but no matter which carb is on the truck, the idle speed, idle mixture (if applicable... some carbs had cast plugs over the mixture screws presumably because they "never need adjustment" HA!) and choke pull-off settings will still have to be set with the carb ON the truck.
IF the carb is indeed an Autolite 2100 or Motorcraft 2150 this is a pretty good write-up on the rebuild and adjustments including the on-car adjustments.
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I love that fricken carb, had the older version on my 78. Usually off idle hesitation would come down to the accelerator pump for me. You have to make sure all of the linkages are set just right for your motor. Visually inspect the choke plate and make sure it's opening up all the way as well, those automatic chokes always screw up in one way or another.
You don't really wanna adjust idle screws if yours is idling OKAY, it's probably not the problem. Those mixture screws are a pain to get right once right and shouldn't have an effect on anything after idle, of course off-idle acceleration counts for that.
Here's one, my 351w would NOT run at 10BTDC without off-idle hestation until after I changed the timing chain. I would have to run it at 14degrees+. Try bumping your timing up a few degrees initial and see if it helps, I'm betting it will.
You don't really wanna adjust idle screws if yours is idling OKAY, it's probably not the problem. Those mixture screws are a pain to get right once right and shouldn't have an effect on anything after idle, of course off-idle acceleration counts for that.
Here's one, my 351w would NOT run at 10BTDC without off-idle hestation until after I changed the timing chain. I would have to run it at 14degrees+. Try bumping your timing up a few degrees initial and see if it helps, I'm betting it will.
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Those plugs have been removed for adjusting. I think they were set to a general setting before installation and fine tuning. I'm not sure what model the carb is. I will check that this weekend when I pick it up.
Sounds like the first steps are examine the accelerator pump, linkage, timing and mixture. Maybe much easier fix than tracking down a vacuum leak!
Sounds like the first steps are examine the accelerator pump, linkage, timing and mixture. Maybe much easier fix than tracking down a vacuum leak!
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