Engine almost dies when i brake
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Engine almost dies when i brake
When I put on brakes, and come to a stop, my engine sputters and almost dies, but recovers quickly. Since this behavior began two weeks ago, I have swapped the carb, fuel filter, fuel pump, brake booster, spark plugs, spark plug wires, distributor, cap, rotor, coil, control module, and the kitchen sink. It's an 84 F150, 300 I6, C6 trans. If i am going down the road, and shift into neutral and coast a while, the engine idles fine until i press the brakes. When I am stopped, pressing the brakes has no effect, so it seems to be a deceleration issue. The problem is the same whether the gas tank is almost empty or full. Any ideas?
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From: Virginia
Did your original carb have a dashpot on the throttle? Should be a little round metal can with a plunger that hits the throttle at idle. It adds a time delay for the throttle to shut completely. Some setups had them, some didn't.
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All the changes i listed were done after the problem started, and none of the changes have had any effect. It doesn't have any trouble when i let off the gas suddenly, and runs great in every way except for the situation i described - braking to a stop while in motion. Thanks for the comment though 
But, to answer your question, no, neither carb has the conventional dashpot, but "had" the idle control solenoid in days gone by. All the engine control things have long been gone, and the truck has run great until two weeks ago, when this odd behavior began.
But, to answer your question, no, neither carb has the conventional dashpot, but "had" the idle control solenoid in days gone by. All the engine control things have long been gone, and the truck has run great until two weeks ago, when this odd behavior began.
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Joined: Jan 2005
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From: Pittsburgh
Its a long shot, but take a look at the butterflies (inside the carb). Make sure the screws aren't snapped off, and the spring is functioning. If the screws snapped the butterflys will sit in place and still function somewhat, and causes this sort of problem.
Fleet Mechanic
Joined: May 2009
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From: Bay Area, Unfortunately
Also check the float level. A sticking needle or fuel level too high could cause extra fuel dumped into the carb, especially when coning to a stop because of the inertia. I rebuilt my carb and even when it was a fresh rebuild, I would get a sticking needle at times.
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