Diaphram question
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Freshman User
Joined: Apr 2007
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Diaphram question
I have a 83 f150 300 straight 6 with a carter 1barrel. I rebuilt the carburetor, but am not sure if i got the right diaphram now that I got it back together and it's a little sluggish when I punch the gas.
The diaphram has 5 holes, 4 are screw holes for the metal that holds the diaphram down. The last hole doesn't seem to lineup to anything. I thought it would go to the outlet for the tube that feeds fuel to the throat of the carb, but it doesn't line up. If this is the right diaphram, where does the side with the extra hole face?
Thanks
The diaphram has 5 holes, 4 are screw holes for the metal that holds the diaphram down. The last hole doesn't seem to lineup to anything. I thought it would go to the outlet for the tube that feeds fuel to the throat of the carb, but it doesn't line up. If this is the right diaphram, where does the side with the extra hole face?
Thanks
Ford Parts Specialist
Joined: Nov 2006
Posts: 88,826
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From: Simi Valley, CA
I have a 83 f150 300 straight 6 with a carter 1barrel. I rebuilt the carburetor, but am not sure if i got the right diaphram now that I got it back together and it's a little sluggish when I punch the gas.
The diaphram has 5 holes, 4 are screw holes for the metal that holds the diaphram down. The last hole doesn't seem to lineup to anything. I thought it would go to the outlet for the tube that feeds fuel to the throat of the carb, but it doesn't line up. If this is the right diaphram, where does the side with the extra hole face?
Thanks
The diaphram has 5 holes, 4 are screw holes for the metal that holds the diaphram down. The last hole doesn't seem to lineup to anything. I thought it would go to the outlet for the tube that feeds fuel to the throat of the carb, but it doesn't line up. If this is the right diaphram, where does the side with the extra hole face?
Thanks
If you bought a Motorcraft carb kit, I can tell you if the carb kit/diaphragm is correct or not...as long as you give me the carb kit part number off the box.
If you bought an aftermarket kit from an autoparts store, I can't help you.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Where is the hole in the diaphragm? There shouldn't be any holes in it; that defeats the purpose. There are other holes in the pump cover, but the diaphragm should isolate the two sides of the pump.
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The 5 holes are not in the actual working part of the diaphram. They are around the outside of the rubber. 4 of them are screw holes. The other hole is a little more inside and to the right of one of the screw holes. I am concerned because it almost looks like this hole should line up with the outlet for the tube that sends fuel to the motor, but it doesn't.
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I'm attaching a picture of the old diaphram, and it is exactly the same as far as hole placements. It was stuck to the bottom of the carburetor and didn't pump at all. The arrow is pointing towards the hole in question. Not sure if it's in the right spot, and if it is, I'm not sure I put it on the right side.
MSEE
Joined: Apr 2004
Posts: 10,386
Likes: 35
From: Austin, TX
Oh yeah, I remember that hole. On my carburetor, I believe there was a corresponding hole that matched to that, in the pump housing. On the pump housing, that hole goes to a small inch-long tube that goes up to the throttle body. I don't have a picture so it's hard to describe, but I do remember that. Check both the diaphragm mounting surface and the pump housing for the corresponding hole. If you don't have a matching one, then don't worry about it. I don't believe later model ones have it. If you don't have the hole, it will just seal itself naturally since it's on the edge.
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Thanks, the housing assembly does have the hole and fitting for the tube, but it doesn't line up with the extra hole on the diaphram. As near as I could tell on the paper that came with the rebuild kit, the extra hole goes toward the back of the carb, or the side of the carb that the choke is located. I did it this way. Hopefully I can tune it a little more and get it to stop smoking(it's just a little greyish smoke) and get it to rev a little better than it does now. I bought a cheap vacuum guage, we'll see if I can figure it out.
Thanks again
Thanks again
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