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Old 10-10-2010, 03:29 AM   #1
Orange77
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fluctuating fuel flow

wondering what could cause this i have a clear fuel filter and sometimes its full sometimes its half or below full and other times its spitting is my fuel pump going out? The fuel pressure gauge i had on the fuel line between the carb and the filter went out recently but last time i checked the pressure on it it would jump up and down as well. any ideas what could cause this?
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Old 10-10-2010, 11:13 AM   #2
old Rusty C10
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Re: fluctuating fuel flow

on the 77 i assume you have a mechanical pump..it could have an issue with the diaphram in it or there could be an issue with junk blocking flow by the sock in your tank.. is this at idle?
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Old 10-10-2010, 12:57 PM   #3
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Re: fluctuating fuel flow

yea its at idle. i have noticed that sometimes it just doesn't run as well as other times kinda feels a little bogged down
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Old 10-11-2010, 12:34 PM   #4
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Re: fluctuating fuel flow

anybody have an issue like this before?
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Old 10-11-2010, 07:29 PM   #5
Rich-Red86SB
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Re: fluctuating fuel flow

Big block or small block ? How old is the fuel pump ? and is your fuel cap vented or closed ? I pulled the socks out of my 76 GMC (dual tank) and they were nasty dirty.
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Old 10-13-2010, 01:19 AM   #6
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Re: fluctuating fuel flow

Small Block, bout 3 or 4 years old, both saddles are vented only use one think that selector valve is busted stalls out if i switch it over, and i dont know what you mean by socks never dealt with the tanks before...
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Old 10-13-2010, 01:29 AM   #7
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Re: fluctuating fuel flow

Had a similar issue - it was very intermittent though and I never corrected it. I always suspected the fuel pump diaphram. Both tanks were vented and vents worked well (never any pressure when removing the cap). All the lines and connections were good. I'd start there - it's a pretty cheap part.
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Old 10-14-2010, 10:31 PM   #8
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Re: fluctuating fuel flow

so think i should just replace the whole pump?
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