Classic Mustangs (Tech) Technical discussions about the Mustangs of yester-year.

fuel pump pressure

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Old Mar 31, 2008 | 06:05 PM
  #1  
dirtydave289's Avatar
dirtydave289
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From: Newnan, GA
Default fuel pump pressure

so i've been having some problems with my floats (i believe)
they've been getting stuck and my carb just dumps gas..but it only happens sometimes
at least i think it's the floats getting stuck..i cleaned them and it's better now
but i went to change my fuel filter and when i took the hose off the filter there was a lot of pressure and gas flew all over..but when it's hooked up no gas pushes its way out my carb or anything..it idles fine, runs fine.
but why was there so much pressure? i had just shut my car off
Old Mar 31, 2008 | 06:10 PM
  #2  
67t5ponycoupe's Avatar
67t5ponycoupe
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From: Colorado
Default RE: fuel pump pressure

That is the way it works. There is gas pressure in the line because the needle and seat act as a valve to shut the flow of gas. If the car sits for a long time without being started then gas evaporates from the bowl, the float drops allowing more gas into the the bowl and relieving the pressure on the line from the pump to the carb.
Old Mar 31, 2008 | 08:32 PM
  #3  
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dirtydave289
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From: Newnan, GA
Default RE: fuel pump pressure

oh ok so it having some pretty good pressure is normal?
i took off the hose and it sprayed all over..thought it might of been too much pressure
thanks!
Old Mar 31, 2008 | 09:28 PM
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john721
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From: Florida
Default RE: fuel pump pressure

Same thing happened to me. I couldn't believe how much had built up....it actually "perculated"...and kept coming! I have a fuel pressure gauge, and it reads around 9 lbs.
Old Mar 31, 2008 | 09:46 PM
  #5  
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mjr46
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From: West Virginia
Default RE: fuel pump pressure

ORIGINAL: john721

Same thing happened to me. I couldn't believe how much had built up....it actually "perculated"...and kept coming! I have a fuel pressure gauge, and it reads around 9 lbs.
if your getting 9psi...that's way to much and will overcome the spring tension on the needle and seat and push excess gas in..you need to get a regulator on it and pull it back to around 5 to 5.5 psi max......if you have a little filter that screws on to the stock style carb...unscrew it and try and blow through it..I had one once that was partially restricted and allowed excess pressure to build up
Old Mar 31, 2008 | 09:51 PM
  #6  
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john721
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From: Florida
Default RE: fuel pump pressure

OK.... you learn something new every day! Thanks for the advice
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