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Sai Li Fuel sysem and dropping rail pressure (2018)--Log attached

Dennisn

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Had a buddy had same issue. Turned out his was a bad pump.
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Kona 18

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Are you using a Hobbs switch? If so, make sure it's actually working, if not, it almost looks like one of your pumps is not working, based on the fuel pressure before it tanks, im assuming you are running 55psi base pressure with no boost reference since pressure doesn't go up much when you build boost and it only seems to fall off a cliff instead.

Verify your grounds first, you might have a bad or loose ground which could be preventing the one of the two pumps from kicking on, if you are grounding to the stud on the FPDM(left side) then that could be the issue, use the bolt on the right side of the FPDM instead.
 
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gimmie11s

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So I’ve confirmed this problem is a factory rail issue.

However, instead of paying $400+ to fix the issue (with new rails), I’ve simply fixed the problematic factory rail by adding another feed for the port injectors on the passenger side.

I’ll update my build thread as well, but new logs confirm I now am able to hold 58-60 psi port rail pressure on 10 psi boost.

Hells yes!!


52-B82-D4-F-DF1-C-4218-B594-5-BA9-CBC226-B9.jpg


5-FD54339-081-F-484-F-8-D9-B-92-E8-B62298-A2.jpg


62-B68-C26-5-BDE-4631-99-D4-5-F356-CC91-DAD.jpg


F438316-A-4-F7-F-4-D1-E-95-DB-C8-BE50-FBF337.jpg
 

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whatsup62

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So is this a rail issue with 18+ cars? Never had a problem on my 15.
 

Toy Cobra

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I believe the 18 rail is smaller and won’t support the same hp as earlier cars. I went With a Fore to fix it once and for all.
 
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gimmie11s

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I believe the 18 rail is smaller and won’t support the same hp as earlier cars. I went With a Fore to fix it one and for all.
Nice but no need with the fix I posted above.... depending on your HP goals of course!
 

beefcake

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the 18 fuel rails def do not flow as well as the 11-17 rails, ford basically cut capacity because the DI system especially on an n/a application can handle almost the entire load of fueling for the cars.

for e85, we def recommend upgrading the rails if your on a system that didn't come with rails
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