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Turbo/Haltech V6
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1,713 Posts
Discussion Starter · #1 ·
The guys tuning my car have ran into a low fuel pressure problem. They were tuning the car at 9psi, but the car started to go lean at high RPM's. They have been troubleshooting the problem and so far the fuel pump, FPR, fuel filters, injectors, and lines seem to be good. Any more ideas of what could be wrong? Thanks for your help.
 

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Turbo/Haltech V6
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1,713 Posts
Discussion Starter · #3 · (Edited)
What FPR are you using? What diameter of lines are you using? What fuel pump? Do you stilll have the stock FPR installled with the new one?
I have:
-VR4 Fuel rails + 3SX loop
-Walbro 255lph Fuel Pump
-Precision 550cc peak and hold injectors
-Aeromotive A1000-6 Injected Bypass Regulator
-6an Braided fuel lines
-Earl’s in line fuel filter
 

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Resident Asshole
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5,940 Posts
Check the fuel pump grommet in the fuel pump assembly.
 

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Resident Asshole
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5,940 Posts
Also, Walbro's go bad but still run. They have a problem sometimes feeding higher line pressures but can idle just fine. I've seen it happen way too many times now and in the end, a new fuel pump solves the problem.
 

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Banned
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2,052 Posts
Check the grommet, the guy I bought my car from just replaced mine before he sold it to me and gave me a extra. I am also using the Walbro

On the subject of the bad fuel pump, explain to me Pharm about the pump being bad but still working. Right now my car will not start but but it has Spark and its feeding fuel through the lines. I got to get the car started soon, its been down for about 3 months now.
 

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Registered
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51 Posts
i JUST fixed this on my RIPPed GT. that little tiny grommet on the top of the fuel pump had a crack in it from the previous owner's shitty installation. i had the damn thing apart 3 times checking fuel lines, FPR, and the pump. little bugger is like $1.70 from the dealer, so i bought 6, knowin it'll probably happen again.
 

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Banned
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2,052 Posts
i JUST fixed this on my RIPPed GT. that little tiny grommet on the top of the fuel pump had a crack in it from the previous owner's shitty installation. i had the damn thing apart 3 times checking fuel lines, FPR, and the pump. little bugger is like $1.70 from the dealer, so i bought 6, knowin it'll probably happen again.
m05z I just replied to your PM, but I was wondering if the grommet kept the car from starting?
 

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Resident Asshole
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5,940 Posts
Yes, the grommet can keep the car from starting. The car will sound like it wants to start but will not fire up.

In regards to Walbro's going bad... A fuel pump is simply an impeller. Those impellers can degrade and then not output sufficient flow at a given PSI.
 

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Turbo/Haltech V6
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1,713 Posts
Discussion Starter · #11 ·
Also, Walbro's go bad but still run. They have a problem sometimes feeding higher line pressures but can idle just fine. I've seen it happen way too many times now and in the end, a new fuel pump solves the problem.
They told me that they have tried 3 different brand new fuel pumps and the problem doesn't go away. I'll tell them about the grommet. Thank you all for your help . You guys are awesome.
 

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Stage 1 SDS @11+ psi
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3,058 Posts
mine at idle is about 50 psi, but of course it was around 20 when my grommet needed replaced.
50 psi. is the fuel pressure at idle without vacuum. Did you do this purposely? Typically, curb idle pressure is 39 psi and 50 psi at zero vacuum or 0 psi of boost. If you have a run rich problem, then you know why.
 

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Stage 1 SDS @11+ psi
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3,058 Posts
The guys tuning my car have ran into a low fuel pressure problem. They were tuning the car at 9psi, but the car started to go lean at high RPM's. They have been troubleshooting the problem and so far the fuel pump, FPR, fuel filters, injectors, and lines seem to be good. Any more ideas of what could be wrong? Thanks for your help.
Ummm, I didn't see if you have a fuel pressure gauge, nor did anyone mention it. You need one to confirm if you pressure is low or not.
 

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Resident Asshole
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5,940 Posts
50 psi. is the fuel pressure at idle without vacuum. Did you do this purposely? Typically, curb idle pressure is 39 psi and 50 psi at zero vacuum or 0 psi of boost. If you have a run rich problem, then you know why.
Come now, Phil you should remember that older SDS kits REQUIRED the fuel pressure on the line to be at 50+ psi! Ripp was so smart, I wonder why they couldn't control fuel trims and had to invent a brat, er... I mean once again resell someone else's electronics since the bb didn't work out so good. ;)
 

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Stage 1 SDS @11+ psi
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3,058 Posts
Come now, Phil you should remember that older SDS kits REQUIRED the fuel pressure on the line to be at 50+ psi! Ripp was so smart, I wonder why they couldn't control fuel trims and had to invent a brat, er... I mean once again resell someone else's electronics since the bb didn't work out so good. ;)
Oh yeah, lest I forgot. ;)
 

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Turbo/Haltech V6
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1,713 Posts
Discussion Starter · #20 ·
Sorry for taking so long to reply. I talked to the guys fixing my car and they told me that the low pressure problem was fixed by replacing the in-tank fuel filter with a new filter. Also, another problem that I had was that my wideband was still reading lean. So when they tested the sensor in a different car, they found that the sensor was messed up. A new sensor should be here by next week. Thank you guys for the help.
 
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