Won't start without priming carb.
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From: North, Ga.
Won't start without priming carb.
Hello everyone. I have an 85 F-150 with the 300 six cylinder that has been sittting for a year or so. It was my dad's truck and he passed away last june. I have been trying to get it going and fix a few things on it and I am having a fuel issue. If I prime the carb with some gas it will start and die, but after a few times it will take off and run. It runs pretty good once it is up and going, and will restart easily for the rest of that day. But If left for a couple of days I have to prime it all over again. What would you more knowledgeable folks think the issue would be here? I plan to rebuild the carb and replace the fuel filter in the next few days, but was thinking it may need a pump as well.
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From: Virginia
1. Take the aircleaner off and while looking down the carb throat, push the throttle open. You should see gas squirt into the engine when you do this. If you did, that means the accelerator pump is working.
2. Did you have to move a little metal door on top of the carb out of the way to see down in the throat with a flashlight? If the little metal door was not in the way, then that's a problem. The metal door is called the choke, and it blocks the air going into the carb when the engine is cold, to make the engine run richer(have more fuel) when it's cold so it will run.
So if you get the metal door to shut, and pat the gas pedal a couple of times to shoot some fuel into the engine, it should start. Then as it warms up the choke door should slowly open. If you have a big round black thing on the side of the carb, you can turn this to make the door open or shut more or less.
2. Did you have to move a little metal door on top of the carb out of the way to see down in the throat with a flashlight? If the little metal door was not in the way, then that's a problem. The metal door is called the choke, and it blocks the air going into the carb when the engine is cold, to make the engine run richer(have more fuel) when it's cold so it will run.
So if you get the metal door to shut, and pat the gas pedal a couple of times to shoot some fuel into the engine, it should start. Then as it warms up the choke door should slowly open. If you have a big round black thing on the side of the carb, you can turn this to make the door open or shut more or less.
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From: Virginia
If the engine has been sitting over night and is cold, push the gas pedal once, then go out and check the choke. It should be shut with some pressure on it. It should not be open at all, not even a crack. When the engine starts, there should be a lever on it somewhere called a "choke pull-off" that will crack the choke open(it works on engine vacuum) and that will keep the engine from "choking out" from the door staying shut. If this is not working, someone may have messed with the adjustment on the choke to "open it up" a little bit.
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From: North, Ga.
I will give it a good looking over once I get it hauled home tomorrow. I am pretty mechanically inclined, but haven't worked on anything with a carb in a long time. I don't know much about the fords, but plan to restore this one somewhat and use it for a hunting truck and work truck.
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From: North, Ga.
Thanks for the replies folks. I have the truck at home now and the accelerator pump is shot for sure. The choke also isn't working at all. I will post some pics and start a build thread later once I give it a good looking over and take some pictures. I decided to drive it home and that was an adventure for sure. I plan to rebuild the carb and give her a good tune-up along with all new fluids and filters over the next couple of weeks.
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From: Central CA
Webstar61, I have the same truck and wondering if I have the same problem! I noticed a wear spot on the rubber fuel hose from the power steering unit, but it does not leak fuel. So question, you figured you were pulling air but it wasn't leaking fuel? I would think fuel pressure would cause it to leak.
Obviously, the best direction here would be to just replace the hose, but I'm curious between pulling air or leaking fuel!
Obviously, the best direction here would be to just replace the hose, but I'm curious between pulling air or leaking fuel!
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From: Denver Metro Area, CO
If there's a mechanical pump on the engine pulling from the tank, there isn't any outward pressure in the tubing.
Contrast this with electric pumps in the tanks that push fuel towards the engine.
My rubber pieces in the same locations had dry rotted and crumbled and I don't remember detecting any leaking fuel but maybe I just never saw it....
Contrast this with electric pumps in the tanks that push fuel towards the engine.
My rubber pieces in the same locations had dry rotted and crumbled and I don't remember detecting any leaking fuel but maybe I just never saw it....
Thread Starter
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Senior User
Joined: May 2011
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From: North, Ga.
Webstar61, I have the same truck and wondering if I have the same problem! I noticed a wear spot on the rubber fuel hose from the power steering unit, but it does not leak fuel. So question, you figured you were pulling air but it wasn't leaking fuel? I would think fuel pressure would cause it to leak.
Obviously, the best direction here would be to just replace the hose, but I'm curious between pulling air or leaking fuel!
Obviously, the best direction here would be to just replace the hose, but I'm curious between pulling air or leaking fuel!
If there's a mechanical pump on the engine pulling from the tank, there isn't any outward pressure in the tubing.
Contrast this with electric pumps in the tanks that push fuel towards the engine.
My rubber pieces in the same locations had dry rotted and crumbled and I don't remember detecting any leaking fuel but maybe I just never saw it....
Contrast this with electric pumps in the tanks that push fuel towards the engine.
My rubber pieces in the same locations had dry rotted and crumbled and I don't remember detecting any leaking fuel but maybe I just never saw it....
New User
Joined: Oct 2012
Posts: 8
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Mechanical Fuel Pump
My 83 had a mechanical fuel pump and only noticed a fuel smell when I completely filled the tank. Bought a new tank and sending unit figuring the tank had a rust hole on the top the reason for smelling fuel only when completely full.
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