can't figure it out, HELP!
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Elder User
Joined: Jul 2006
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From: Maricopa
can't figure it out, HELP!
My brother bought a 75 f-150 with a 390 and a c-6 tranny. when he got it it had been sitting for a couple years, and the oil looked horrible, so he changed the oil, did a coolant flush, changed the fuel lines and pump, put a new carb on (or rather an old one we had laying around) drove fine for a day, now it idles fine, but when you put it in drive, it kills unless you are flooring it, and when flooring it in drive the fastest it will go is about 15-20 mph. tried adjusting the carb, no luck, tried three other carbs, no luck. the manifold had a hole that was suspected to be causing vacuum leak, plugged it, no luck. searched all over for vacuum leaks, couldn't find any, now we're lost. any help would be greatly appreciated.
also posted on the FE Forum
also posted on the FE Forum
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
Likes: 785
From: Simi Valley, CA
My brother bought a 75 f-150 with a 390 and a c-6 tranny. when he got it it had been sitting for a couple years, and the oil looked horrible, so he changed the oil, did a coolant flush, changed the fuel lines and pump, put a new carb on (or rather an old one we had laying around) drove fine for a day, now it idles fine, but when you put it in drive, it kills unless you are flooring it, and when flooring it in drive the fastest it will go is about 15-20 mph. tried adjusting the carb, no luck, tried three other carbs, no luck. the manifold had a hole that was suspected to be causing vacuum leak, plugged it, no luck. searched all over for vacuum leaks, couldn't find any, now we're lost. any help would be greatly appreciated.
Bogging down, hesitating, stumbling from a dead stop or accelerating at speed: Time for a new Accelerator Pump and Check Valve.
The check valve is the same 1962/79: C4AZ9576A (Motorcraft CM825).
There are two different acc. pumps: 1962/74 is the same (C4AZ9B559A-Motorcraft CM463). 1975/79 is different: D5AZ9B559A (Motorcraft CM2092).
Hole in the intake manifold: This is where the choke's pre-heat tube connects.
T'other end connects to a fitting on the choke body. Most autoparts stores carry a 'universal' pre-heat tube kit....
Consists of copper tubing, nylon "blanket" for the tube, nuts and ferrules.
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