Supercharged Mustang having fuel pressure issues

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Brsmustng93

New Member

Mar 20, 2008

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Oct 4, 2008

#1

• Oct 4, 2008

• #1

I recently took my car and had it tuned by an SCT tuner, when I got the car back it ran great no problems, now all of a sudden my fuel pressure at idle is jumping around from 25-30psi, when I remove the vac line to the regulator the needle on the gauge sits dead on 25psi and won't move. I replaced the fuel filter today thinking that might be the problem but no luck. I do not think its the pump cause when I turn the key I hear the pump prime. My current fuel set up is 39lb ev6 injectors, 255lph fuel pump, and a BBK fuel pressure regulator. I also called the tuner and he said he set the Fuel pressure at 39psi with the vac off. Any help would be great thanks.

 

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Denise

New Member

May 22, 2008

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Miami

Oct 4, 2008

#2

• Oct 4, 2008

• #2

I would suggest taking it to the tuner so he can look over the car and take another look at the tune.

I myself have had problems with some tuners 1. I took my car in to get tuned and it had a hiccup when I got it back. Ended up getting new coil packs and problem solved. 2. Fixed the vaccum lines and the car started shutting off, had to rewrite the bottom end of the tune.

 

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uedlose

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Jan 24, 2001

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Charles Town WV.

Oct 4, 2008

#3

• Oct 4, 2008

• #3

maybe the reg is gone bad. How does it run with FP being that low it should be running rough also. maybe the gauge is on its way out. if you could find a way to block the fuel return and then look at the FP if it spikes way up that should help rule out the pump. Have you run over any thing that could of hit the fuel lines and crimped one? check to make sure that the lines back at the tank the plastic one are not crimped any where also up at the front where the lines go to the rails.

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

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Oct 4, 2008

#4

• Oct 4, 2008

• #4

uedlose said:

maybe the reg is gone bad. How does it run with FP being that low it should be running rough also. maybe the gauge is on its way out. if you could find a way to block the fuel return and then look at the FP if it spikes way up that should help rule out the pump.

Click to expand...

This was my first line of thinking as well. Fuel line crimping pliers can help with blocking the return line to see if pressure spikes afterwards.

If the car runs mint, it would not be the first time a gauge went wonky. Having a diagnostic FP gauge (which can be loaned out from some parts stores) can help determine that.

Good luck.

 

ej95cobra

Member

Oct 26, 2003

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Southeastern PA

Oct 4, 2008

#5

• Oct 4, 2008

• #5

Mine sits at 28-30 PSI at idle and is actually running rich. My fuel pressure with vac off is at 40 psi. I have 36# injectors and a 255lph fuel pump.

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

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Oct 4, 2008

#6

• Oct 4, 2008

• #6

FWIW, min spec at any time is 30 PSI.

 

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uedlose

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Charles Town WV.

Oct 5, 2008

#7

• Oct 5, 2008

• #7

I run my F/P at 39-40 with the vac line on and it goes to 42 with it off.

 

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Brsmustng93

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Mar 20, 2008

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Oct 5, 2008

#8

• Oct 5, 2008

• #8

Started the car today and drove it around the block, it seemed okay except the idle was surging alot on start up. When I got back home I checked the fuel pressure gauge is now reading 20 psi. What could make the pressure keep dropping?

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

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Oct 5, 2008

#9

• Oct 5, 2008

• #9

Brsmustng93 said:

Started the car today and drove it around the block, it seemed okay except the idle was surging alot on start up. When I got back home I checked the fuel pressure gauge is now reading 20 psi. What could make the pressure keep dropping?

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Again, do you know that your gauge is working properly on a consistant basis. Your car should have been idling like crap at 20 PSI.

Have you tried any of the suggestions made already? Have you pulled codes - you should have an A/F code if your FP is moving around that much.

 

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uedlose

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Jan 24, 2001

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Charles Town WV.

Oct 6, 2008

#10

• Oct 6, 2008

• #10

^^^^^^^^^ ditto

 

LordMustangGT

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Jan 9, 2006

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Port Orchard, WA

Oct 6, 2008

#11

• Oct 6, 2008

• #11

I just had a buddy of mine have he pump go out slowly. It still ran but fuel presure was low enough that above 3 grand it just felt like it had no power. Replaced the pump with a 255lph and all problems fixed,.... This was a pretty much stock car too.

 

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Brsmustng93

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Mar 20, 2008

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Oct 7, 2008

#12

• Oct 7, 2008

• #12

Yeah I checked the fuel pressure gauge its fine, I also tried adjusting the fuel pressure with my BBk regulator and could not get it to rise at all. Does this mean the pump is going??

 

HISSIN50

"How long does it take to get help in here?

15 Year Member

Nov 29, 1999

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Oct 7, 2008

#13

• Oct 7, 2008

• #13

Brsmustng93 said:

Yeah I checked the fuel pressure gauge its fine, I also tried adjusting the fuel pressure with my BBk regulator and could not get it to rise at all. Does this mean the pump is going??

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Re-read the posts. The next step I would take was already outlined.

Good luck.