VAriable Venturi Carb Diaphragm Replacement

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Mar 15, 2003 | 07:10 PM

interwoven

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VAriable Venturi Carb Diaphragm Replacement

I have a 1983 f150 pickup with a 351. I have the carb off and on the bench and the back cover over the diaphragm off and the small top plate . I need to know how to get that diaphragm off, Do i have to further disassemble the carb? The diaphragm actually looks good but since I'm this far i'm just going to replace it. The darn truck starts right up but just runs rough and loads up with gas when you try to accelerate and gets about 5 miles to the gallon. Going to check the egr valve in the morning. Any other ideas greatly appreciated.

Mar 16, 2003 | 10:27 PM

dro man

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Joined: Feb 2003

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From: Arkansas

VAriable Venturi Carb Diaphragm Replacement

you need to loosen all the screws on top of the carb, remove the aircleaner attaching bolt and carefully lift the rear of the carb up to disenguage the diaphram. be sure when reassembeled to check the cer linkage. Thats( cold enrichment rod) at the top front of the carb. Its real easy to get this rod bound up and it will make it run rich. It should move up and down with finger pressure if i remember correctly.

Mar 17, 2003 | 07:53 AM

interwoven

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VAriable Venturi Carb Diaphragm Replacement

Thanks for the help. I did get the new diaphragm in and it is running alot better but I think my main problem was leaking around the gaskets between the carb and spacer and spacer and intake. These were both pretty whipped. It idles real smooth now, runs without loading up but still doesen't seem quit right. I floor it going up a hill and it just doesn,t seem to have any omph. Maybe thats just the way it is. It's the 351 engine with 80000 miles on it. One thing I noticed is the diaphragm that was in there had an indentation where the spring rode in the diaphragm. The new one had a blue plastic cover over the indentation and this made the spring stiifer and the slides in the top of the carb didn't open as far. I turned that hex screw in the back of the cover over the diaphragm and adjusted them so that they almost open all the way. Didn't seem to make much difference. Thanks again and if you have any other suggestions I'd be glad to hear them.