whats the right fuel pressure? - MustangForums.com



5.0L (1979-1995) Mustang Technical discussions on 5.0 Liter Mustangs within. This does not include the 5.0 from the 2011 Mustang GT. That information is in the 2005-1011 section.

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Old 03-19-2008, 04:07 PM   #1
my77stang
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Default whats the right fuel pressure?

for this piece of crap bronco II im working on. they are 14 lb injectors and im getting 34 lbs of pressure @ idle, and 42 lbs. @ idle when i unhook the vacuum line that goes to the regulator. does this sound about right?
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Old 03-19-2008, 06:18 PM   #2
MustangMan628
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Default RE: whats the right fuel pressure?

What motor in the bronco II? Sounds just a hair low for a V-6 fuel injected. But it's close to the right range
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Old 03-19-2008, 06:20 PM   #3
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Default RE: whats the right fuel pressure?

Yeah, I think basically all older fuel injected motors ran around 35-40 lbs. of pressure. 42 flat out would be okay for that range, what's wrong with it? That's nto low enough pressure for the thing to cutoff, maybe run a little sluggish, when I got my mustang, it would idle at 19 lbs of pressure before it'd cut off after a minute or two. Then had to prime the pump over and over lol
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Old 03-19-2008, 06:40 PM   #4
Joel5.0
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Default RE: whats the right fuel pressure?

Quote:
ORIGINAL: my77stang

for this piece of crap bronco II im working on. they are 14 lb injectors and im getting 34 lbs of pressure @ idle, and 42 lbs. @ idle when i unhook the vacuum line that goes to the regulator. does this sound about right?
Yep....30-45 psi is within spec......
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Old 03-19-2008, 07:16 PM   #5
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Default RE: whats the right fuel pressure?

its a 2.9 V6

Quote:
Yep....30-45 psi is within spec......
ok cool, its been idling rough and has no power. it has new wires, cap/rotor, plugs, fuel filter, air filter. no error codes and its pissing me off. cold cranking compression was 70-80 on all cylinders. the guy i borrowed the fuel pressure gauge from said 38-42, so i was worried about 33/34.

i just scored 9 motorcraft injectors (brand spankin new in the boxes) on ebay for 45 bucks shipped (friggen autozone wanted 60 bucks EACH), so im gonna swap em and see what happens.

if anyone needs a 14 lb injector for something let me know i'll have 3 extra [8D]
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Old 03-19-2008, 08:15 PM   #6
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Default RE: whats the right fuel pressure?

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ORIGINAL: my77stang

cold cranking compression was 70-80 on all cylinders.
I know you specified cold, but that's not a good number...........
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Old 03-19-2008, 08:21 PM   #7
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Default RE: whats the right fuel pressure?

yeah....isnt like, 150 a normal number cold? 180-210 warm or with some oil squirted i nthe cylinder? correct me if im wrong

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Old 03-19-2008, 10:43 PM   #8
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Default RE: whats the right fuel pressure?

70-80 wtf shane!!! you need at leat 100 psi as a general rule of thumb to have complete cumbustion.. if those numbers are correct.. you got a tired motor
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Old 03-20-2008, 09:25 AM   #9
my77stang
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Default RE: whats the right fuel pressure?

oh im sure its tired..... but it should run weak, not erratic.

btw, i checked my 289 cold and it was only 90 lbs. i know the motor hasnt had a chance for the rings to seat, but you'd think with flat tops and zero decked it would be higher.
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Old 03-20-2008, 08:47 PM   #10
5spd GT
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Default RE: whats the right fuel pressure?

Static compression of the Bronco II?
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