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 Mechanical fuel pump? 
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Joined: Wed Oct 23, 2013 8:01 am
Posts: 108
How much vacuum should a pump pull? It's a Carter 120 street pump.
Reason I'm asking is I'm having a low pressure issue, pump will pull 11" vacuum & it doesn't hold it.


Sat Jul 30, 2016 9:12 am
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Joined: Fri Feb 08, 2013 2:37 pm
Posts: 1701
The check valves in a mechanical fuel pump are not intended to be air tight, so "doesn't hold it" is not unusual. It probably has a chunk of something, Teflon tape or a sliver of rubber, in a check valve. You can take it apart and clean it out, if you haven't already. 11" Hg is 5.4 psi, how much do you expect it to pull? Does it hold fuel pressure on the output side?


Sat Jul 30, 2016 6:32 pm
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Joined: Wed Oct 23, 2013 8:01 am
Posts: 108
No it doesn't hold pressure. So they pull the same as they put out. Cause it puts out 5.5 lbs. but drops to about 3 when I go WOT & leans out after that.
I thought maybe it wasn't pulling hard enough, could have some kind of restriction farther back I guess.


Sat Jul 30, 2016 10:44 pm
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Joined: Wed Oct 23, 2013 8:01 am
Posts: 108
Took it apart cleaned it there was some junk in it. Haven't rechecked the pressure yet, but it did pull through 2nd without leaning out.


Sat Aug 06, 2016 10:53 am
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