# Fuel pressure drop after top feed fuel rail + big injectors
**URL:** https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328
**Category:** SON240sx Automotive
**Created:** [July 17, 2009, 12:13pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328 "2009-07-17T12:13:42Z")
**Posts on this page:** 13
**Page:** 1
### Author:  [@Tacoboy](https://forums.speedlife.net/u/Tacoboy)
#### Post date: [July 17, 2009, 12:13pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/1 "2009-07-17T12:13:42Z")
Hey guys, Im fucking stumped.
Put in 660 CC top feed injectors, and an OBX top feed rail. For the life of me, I cannot figure out what my issue is. For troubleshooting sake, I have a walbro 255, have bridged the gap where the fuel filter is (to elimate that as a cause).
My AEM fuel pressure regulator has been grate to me. 1:1 rise in fuel pressure with the stock rail and stock 370’s. Now, when i watch the gauge, it drops from 45 psi to 15-20 when I crack the throttle. Pinching the return line yields the same result.
Is my pump not moving enough fuel to the rail?
Is the FPR fucked?
Does make sense to me, as there is tonnes of presure (55 psi if i turn it up), but the pressure drops so rapidly when I rev it up. I have also tried claming the FPR return line to see if it pressure drops, and it does. SO I beleive the problem is between the fpr and the rail - possibly the pump (but that doesnt make much sense)
HALP!
Dave
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### Author:  [@Hurricane](https://forums.speedlife.net/u/Hurricane)
#### Post date: [July 17, 2009, 12:19pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/2 "2009-07-17T12:19:50Z")
Time for a better fuel pump.
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### Author:  [@Tacoboy](https://forums.speedlife.net/u/Tacoboy)
#### Post date: [July 17, 2009, 1:22pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/3 "2009-07-17T13:22:32Z")
Im confident the wallbro 255 is adequate for this, no?
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### Author:  [@50sentra](https://forums.speedlife.net/u/50sentra)
#### Post date: [July 19, 2009, 6:36am UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/4 "2009-07-19T06:36:51Z")
Check for cracks on the vacumn line on the FPR.
Seems that the FPR isnt rising in pressure due to an air leak in this line so when you crack the throttle all that happens is pressure is doing is dropping
Where do you have the gage located in the line???
Jeff
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### Author:  [@system](https://forums.speedlife.net/u/system)
#### Post date: [July 19, 2009, 8:30am UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/5 "2009-07-19T08:30:22Z")
you got the fuel lines on and not crossed up? i know its a stupid question but, it could be that simple
farmer
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### Author:  [@simplemind7](https://forums.speedlife.net/u/simplemind7)
#### Post date: [July 19, 2009, 5:29pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/6 "2009-07-19T17:29:12Z")
It’s fixed now, I’ll let him post up with what ridiculous thing he did wrong.
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### Author:  [@Tacoboy](https://forums.speedlife.net/u/Tacoboy)
#### Post date: [July 19, 2009, 6:57pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/7 "2009-07-19T18:57:53Z")
I don’t want to talk about it.
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### Author:  [@ronnie416](https://forums.speedlife.net/u/ronnie416)
#### Post date: [July 20, 2009, 9:45pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/8 "2009-07-20T21:45:40Z")
> [@Does anyone have a Direct X card?](https://forums.speedlife.net/t/does-anyone-have-a-direct-x-card/22853/8):
>
> I don’t want to talk about it.
LOLZ. We all have stories like that dude.
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### Author:  [@Keez](https://forums.speedlife.net/u/Keez)
#### Post date: [July 20, 2009, 10:04pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/9 "2009-07-20T22:04:42Z")
reversed lines i bet! 🙂
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### Author:  [@simplemind7](https://forums.speedlife.net/u/simplemind7)
#### Post date: [July 20, 2009, 11:44pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/10 "2009-07-20T23:44:18Z")
so much stupider than that.
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### Author:  [@Elroy](https://forums.speedlife.net/u/Elroy)
#### Post date: [July 22, 2009, 3:16pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/11 "2009-07-22T15:16:25Z")
pcv valves are not fuel line fittings…hehehe
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### Author:  [@87s15lt1](https://forums.speedlife.net/u/87s15lt1)
#### Post date: [July 22, 2009, 3:38pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/12 "2009-07-22T15:38:24Z")
Wow, I’m surprised I didn’t think of that.
Although, I did say something was reversed eh Dave? heh
Glad she’s all fixed up 🙂
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### Author:  [@simplemind7](https://forums.speedlife.net/u/simplemind7)
#### Post date: [July 22, 2009, 5:18pm UTC](https://forums.speedlife.net/t/fuel-pressure-drop-after-top-feed-fuel-rail-big-injectors/126328/13 "2009-07-22T17:18:25Z")
hahaha, silly dave.