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What is the "Correct Fuel Pressure" for a 3800 conversion ? by Lou6t4gto
Started on: 08-23-2017 06:37 PM
Replies: 14 (678 views)
Last post by: Lou6t4gto on 09-06-2017 12:30 AM
Lou6t4gto
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Report this Post08-23-2017 06:37 PM Click Here to See the Profile for Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
mine starts and holds 45 PSI at idle or the throttle open. Is that Enough ? I believe it is a 5.7 chevy truck pump. LOL
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Lou6t4gto
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Report this Post08-24-2017 11:49 AM Click Here to See the Profile for Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
what PRESSURE is needed for a 3800SC to run correctly ???
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Gall757
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Report this Post08-24-2017 12:13 PM Click Here to See the Profile for Gall757Send a Private Message to Gall757Edit/Delete MessageReply w/QuoteDirect Link to This Post
https://www.fiero.nl/forum/A...041015-2-050410.html

[This message has been edited by Gall757 (edited 08-24-2017).]

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Domtech
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Report this Post08-24-2017 01:31 PM Click Here to See the Profile for DomtechSend a Private Message to DomtechEdit/Delete MessageReply w/QuoteDirect Link to This Post
Have you made the change I suggested in your other thread yet?

With the vac/boost line to the fuel pressure regulator disconnected it should be 52psi.
The vac/boost line adjusts it down or up by how much vacuum or boost is in the intake.
For example, the fuel pressure should be at 56psi if you are making 4 psi of boost.
45psi at idle is normal.
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Lou6t4gto
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Report this Post08-24-2017 03:13 PM Click Here to See the Profile for Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
I'll change that Line and hope. thanks
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Dennis LaGrua
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Report this Post08-25-2017 02:52 PM Click Here to See the Profile for Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
With the 3800SC you MUST use a 2 or 3 BAR fuel pressure regulator. Fuel pressure needs to rise to boost pressure plus the base number of 43-45psi . In other words at 10 psi of boost you should have 53-55 PSI of fuel pressure. If you don't see that fuel pressure at boost, the engine will encounter a lean condition that can blow a piston.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

[This message has been edited by Dennis LaGrua (edited 08-25-2017).]

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Lou6t4gto
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Report this Post08-25-2017 04:24 PM Click Here to See the Profile for Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
now ya "lost me". what is a "2 or 3 BAR regulator" ? all it's got is the round one that came on the engine..
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Domtech
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Report this Post08-25-2017 06:31 PM Click Here to See the Profile for DomtechSend a Private Message to DomtechEdit/Delete MessageReply w/QuoteDirect Link to This Post
All he is saying is you need one for a boosted application. Stock is fine if it is from that engine.

When you move that vacuum line check that no fuel is leaking out the fitting on the regulator. If you see signs of fuel in the line then it is bad.
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Lou6t4gto
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Report this Post08-25-2017 06:55 PM Click Here to See the Profile for Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
original to the engine. No Leaks, no moisture at the fitting.
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Dennis LaGrua
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Report this Post08-26-2017 08:44 AM Click Here to See the Profile for Dennis LaGruaSend a Private Message to Dennis LaGruaEdit/Delete MessageReply w/QuoteDirect Link to This Post
The question to be asked is the fuel pressure rising with the boost? That is why its important to run both a fuel pressure gauge and a boost gauge.
As for BAR; that's barometric/atmospheric pressure of 14.7 psi. A 2 BAR fuel pressure regulator is referenced to 1 BAR level and provides 43-45 psifuel pressure at idle and a rising rate of fuel pressure as boost increases to a 2 or 3 BAR level. In simple terms your fuel pressure must equal base fuel pressure + boost pressure. If it is not either the vacuum line is obstructed/leaking, the regulator is defective or you have a leak in the tank line which connects the fuel pump to the fuel line. Take the car for a drive and measure the fuel pressure as you hit the pedal hard. If the fuel pressure increases the regulator is probably good.

------------------
" THE BLACK PARALYZER" -87GT 3800SC Series III engine, custom ZZP /Frozen Boost Intercooler setup, 3.4" Pulley, Northstar TB, LS1 MAF, 3" Spintech/Hedman Exhaust, Autolite 104's, MSD wires, Custom CAI, 4T65eHD w. custom axles, HP Tuners VCM Suite.
"THE COLUSSUS"
87GT - ALL OUT 3.4L Turbocharged engine, Garrett Hybrid Turbo, MSD ign., modified TH125H
" ON THE LOOSE WITHOUT THE JUICE "

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Lou6t4gto
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Report this Post08-30-2017 01:56 PM Click Here to See the Profile for Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
oK. now I understand what you're saying. but Why would the factory have connected the "Fuel pressure Line" to the "Upper tree" on the Supercharger and not the port at the front of the manifold where the Map sensor is routed ?? Thanks
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Domtech
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Report this Post08-30-2017 04:09 PM Click Here to See the Profile for DomtechSend a Private Message to DomtechEdit/Delete MessageReply w/QuoteDirect Link to This Post
 
quote
Originally posted by Lou6t4gto:but Why would the factory have connected the "Fuel pressure Line" to the "Upper tree" on the Supercharger and not the port at the front of the manifold where the Map sensor is routed ??


They didn't.

This is the factory routing:


Edit: Some older superchargers had a side vacuum/boost tree which is shown on a lot of diagrams. On those cars that is where the fuel pressure regulator attached. That's probably where the confusion came from.

[This message has been edited by Domtech (edited 08-30-2017).]

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codyj
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Report this Post08-30-2017 04:17 PM Click Here to See the Profile for codyjSend a Private Message to codyjEdit/Delete MessageReply w/QuoteDirect Link to This Post
Guy on youtube is doing a 3800 swap and just put in a 45 psi ACDelco pump.
https://www.youtube.com/watch?v=6MQfLHh3LhE&t=6s

[This message has been edited by codyj (edited 08-30-2017).]

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Domtech
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Report this Post09-05-2017 06:53 PM Click Here to See the Profile for DomtechSend a Private Message to DomtechEdit/Delete MessageReply w/QuoteDirect Link to This Post
Did you ever get the problem sorted out?
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Lou6t4gto
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Report this Post09-06-2017 12:30 AM Click Here to See the Profile for Lou6t4gtoSend a Private Message to Lou6t4gtoEdit/Delete MessageReply w/QuoteDirect Link to This Post
not yet, Home projects took over for now. I just hate to take it to a shop & them to charge me to say, "we don't know !"
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