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| 1988 LFX Build Lessons Learned/How to (Page 3/11) |
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Will
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APR 30, 02:03 PM
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| quote | Originally posted by RandomTask:
Currently there is no return and thus, no regulator. The "lift" pump feeds the high pressure pump. I'm installing a regulator on the lift pump circuit. So the fuel pump will feed through a filter, into a regulator. I'll set that regulator to ~55psi. That regulator will have a feed to the high pressure pump and also a return back to the tank. The high pressure pump then feeds the fuel rail and has it's own return system; basically I'm going to make sure there's a constant 55psi to the high pressure pump. I'm utilizing a walboro 255 unit so basically, it's feeding as much as it can so ~100psi, which is no bueno. |
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Ok, so the stock ECM is supposed to PWM the fuel pump, right? I @$$ume there's a reason why you didn't wire it up for that to work?
Yes, the high pressure pumps do not have input regulation, so they essentially dead-head the lift pump without something else in the system.
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Blacktree
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APR 30, 06:32 PM
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If there's no return and no regulator, then it was a PWM controlled fuel pump. The fuel pressure was controlled by varying the speed of the pump.
If you want a return style fuel system, you'll need to retrofit it. But I guess you learned that already.  [This message has been edited by Blacktree (edited 05-01-2021).]
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Daryl M
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MAY 01, 12:05 AM
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msweldon
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MAY 01, 12:52 PM
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With my LF3/LF4 install, which effectively is the LFX, as referenced, seen, and stated in the 2016 ATS Factory Service Manual, just with altered heads and beefed up internals. I have my fuel system wired up although uninstalled to match the OEM layout.
The fuel system for the V6 E36 and E96 ECUs, Camaro/ATS LFX and LF3/LF4 ATSV has a fuel pump controller module or FPCM separate from the ECU. The E36/E96 ECU sends a canbus signal to the FPCM based off of fuel pressure sensors that commands on demand the FPCM to PWM the fuel pressure from a PWM fuel pump to the HPFP with no return line.
I 'think' the non-FPCM setups, such as some of the transverse lfx setups, send the canbus signal to a PWM fuel pump via the Body Control Module, at least that's the best I could ascertain researching wiring diagrams. I chose to wire my setup to mimic the V6 Camaro/ATS/ATS-V setup.
Note: The FPCM, if not the one with the ECU, has to be 'paired' with the ECU through a dealer or GM Tech-II software or current equivalent.
I have seen no return lines in any of the LFX LF3 LF4 setups I've researched thus far. If anyone has please post. The PWM only gives the HPFP what it needs based on sensor input with no return line.[This message has been edited by msweldon (edited 05-01-2021).]
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RandomTask
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MAY 01, 05:26 PM
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'Cause Im an idiot??
Anyway, regulator should be here today or tomorrow. Also waiting for the last of the coolant hoses to get in. Was able to move the coolant tube ends the way I wanted. Welded fairly easily with only one blow through.
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RandomTask
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MAY 01, 05:27 PM
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Will
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MAY 01, 08:25 PM
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Backwards? To deal with your reversed coolant inlet/outlet dealio? [This message has been edited by Will (edited 05-01-2021).]
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RandomTask
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MAY 02, 12:04 AM
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| quote | Originally posted by Will:
Backwards? To deal with your reversed coolant inlet/outlet dealio?
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Yup. Cut them, rotated 90*. Had to weld in about a 4.5" extension on the driver side so it would clear the passenger side tube.
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Daryl M
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MAY 02, 01:54 AM
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| quote | Originally posted by RandomTask:
Yup. Cut them, rotated 90*. Had to weld in about a 4.5" extension on the driver side so it would clear the passenger side tube. |
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Since I was going with a 3 core radiator anyway, I decided to have the radiator inet and outlet switched to opposite sides. Made the process pretty easy. I also moved the reservoir location to the engine compartment.
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Daryl M
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MAY 02, 02:00 AM
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| quote | Originally posted by RandomTask:
'Cause Im an idiot??
Anyway, regulator should be here today or tomorrow. Also waiting for the last of the coolant hoses to get in. Was able to move the coolant tube ends the way I wanted. Welded fairly easily with only one blow through.
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Being a bit harsh on yourself, don't you think? I considered using the Impala fuel pump and controller, but decided that simpler was better. Guess I'll see for sure when I get to the point where I turn the key.
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