1984 Bronco - Bogs down when trying to accelerate

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351W 4V ** 4180C carb

Having a problem with the Bronco. When I press the gas pedal, it the carb bogs down. Can’t drive down the road without pumping the pedal to keep moving. It does start and idle okay. Has new cats, dist, rotor, wires, plugs. The carb is a rebuild from RockAuto. I put on a manual choke. Timing set at 10 bdtc. Vacuum at 19 in. New crate engine last year.

I have adjusted the idle mixture screws to 2.5 turns (2front 2back). I would like the grand masters to advice me on the number of turns for both front and back screws. 

I will be checking the fuel pressure. I have already replaced fuel filter. I haven’t touched the accelerator pump. This vehicle has no obd connector or any way to get codes.

 Any advice appreciated. Thank you.

 

miesk5

96 Bronco 5.0
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Yo MaineBroncoBeast,

 My first thought is the accelerator pump.  See Hesitation During Acceleration @ 

http://recarbco.com/tech-help/basic-troubleshooting/hesitation-2/

For mixture, see http://recarbco.com/tech-help/idle-adjustment-instructions/

For 4180 info, see http://ddilts.net/mustangs/holley_4180/index.html

"Adjusting the Idle Mixture ScrewsThe idle mixture screws only affects idle. They simply control the amount of fuel and air mixture that is delivered at idle.First run the screws in all the way until they seat, lightly. Too hard and you will damage the *****. Now back the ***** out until the specified rpm is achieved. Turning the idle mixture screws clockwise (in) leans the idle mixture. Turning the idle mixture screws counter clockwise (out) richens the mixture.Turn the mixture screws, alternating between the two in 1/4 turn at a time until the engine rpm starts to drop, then turn them back out 1/4 of a turn.When adjusting your idle mixture screws doesn't seem to change the engine rpm much is an indication that there is something wrong and could be an indication of a needed rebuild." by http://www.carburetor-parts.com/Holley-4180-Carburetor-Idle-Mixture-Screw_p_2257.html

Al

 
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Thank you SeaBronc, I checked fuel pressure and no problem. Only thing left to check was accelerator pump and after a small adjustment I finally could rev the engine without bogging down. Now I can step on it and it’s right there. First on race day!

about the mixture screws, they are not accessible and it’s impossible to do the quarter turn sequence. I’ve tried it many times and even have the flexible adjustment tool and bought new mixture screws too. That is why I asked for your best old school starting point. I don’t mind removing the carb and making adjustments but it’s difficult to access if it’s getting better with the vacuum gauge making a small change every time.

I did build a new house last year and used the bronco to haul everything up to my mountain retreat on a half mile drive way one way.

 

miesk5

96 Bronco 5.0
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Yo,

Great!

btw #1, my paternal grandfather had a farm in Union Maine until 1942, then moved tp Fitchburg, Massachusetts after dadmjoined Marines on the 8th.

btw #2, Seabronco is mia, may have sold his 83 and moved on to other interests.

 

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