Question about 1987 Ford F 250

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Have to Pump accelerator repeatedly to start after sitting

Hello, I have a 1987 F-250 with the 7.5 L 460 engine and a Holley 4B carb. When the vehicle sits for more than 8 hours I have to pump the accelerator around 20 times to get it to start. Once it starts it runs great. I read somewhere about some kind of a gasket in the carb that can "backfire". I just want to know if this might be the problem or if it could be something else. Thanks.

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Check the choke, with cold engine open throttle all the way and let go, butterfly on top should be open about1/4", also I would check your accelerater pump diaphragm sit in the carb. look in carb. pump throttle and see if you see gas spray, if you do pump diaphragm is good, if none bad diaphragm

Posted on May 27, 2010

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I got a 1985 international bus with a holley 4160 carb. it only seems to start with starting fuel. How can I get it to start by turning the key?


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Hello, After my 1987 F-250, 7.5 L V-8, 4BBL sits for more than 12 hours I have to pump the accelerator anywhere from 20 to 50 times to get it to start. Once it starts it runs fine. I have replaced every...


That would be a Holley, probably model 4160 carb on it. You need to do a little detective work on this. You either need to adjust the choke or find out where the fuel is going after 12 hours.

First, when the engine is running check the Intake and Carburetor gaskets for vacuum leaks. Also spray by the Vacuum reserve canister (Like a coffee can) with either Choke cleaner or a water mist. Either way the RPM will change if you have a Vacuum leak. Fix the vacuum leak if you find one. The engine needs Vacuum to draw in the fuel for a cold start. There are vacuum ports with gaskets (Hidden until disassembled) where the Choke housing attaches to the main block of the Carburetor. A leak here will mess up the tiny piston inside the Choke. (Its under the Black cover and operates the stepup for cold starts).

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If this does not help, on the next 12 hour interval check for fuel by taking off the strainer on the Carb inlet and remove the line from the carb to the pump. If the fuel line is dry you are losing the Prime to the pump. You must have either a bad pump or a hole in the fuel line from the tank.

Would like to know what you found. The Power pump inside the front bowl of your Holley has a number and you can go to a Holley website to see if it is correct for your truck. The fuel inside the front bowl of your Holley should be enough start the truck. Even if the bowl went dry overnight, the fuel pump would replenish the supply well before 20 to 50 pumps.

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