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Q: Difficulty starting especially on cold engine

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Recently purchased a 1986 F-150, 4.9 inline 6 cylinder 1 barrel carburetor. Truck initially started fine. Added some seafoam and similar cleaning agents to fuel because it is an older vehicle. Truck started to die at idle and have trouble restarting, figured it was carburetor related. Replaced fuel filter and removed and cleaned carb but still same issue. Now the only way I can get it to start is rocking the truck back and forth while turning the key and pumping the throttle. Vehicle will still sometimes stall at idle, and sometimes will start without rocking when engine has reached operating temperature. Have also replaced plugs and wires, have been unable to diagnose cause of failure thus far

My car has 200000 miles.
My car has a manual transmission.

Thanks for writing in about your 1984 Ford F-150 If the vehicle is easier to start when "rocking" the vehicle back and forth, it may be an issue with the fuel pick up inside the gas tank. If for example, it is easier to start when it has more than half a tank vs less than half a tank. Checking the fuel pressure with an inline pressure gauge is a good place to start. Also, check the choke pull off on the carburetor. You will need a hand held vacuum pump to check that. If you need help running these tests, an expert technician from YourMechanic can come to your car’s location to diagnose the cause of the hard start and let you know what should be done.

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