SR20DET Redtop Fuel Issue

[ZenkiDK]

Hello Everyone,

Decided to post after trying to diagnose this problem for the last 3 months. Car was running fine and one day this started to happen.

Mods:
Walbro 255
P2M 720cc injectors
2871r
Z32 MAF
RS Enthalpy Tune
WS Harness
all supporting mods

The Issue/Symptoms:
1. Car floods during startup and doesn't start. It is intermittent/random and doesn't matter if its cold/hot. In order for me to get it started, I have to remove the fuel pump fuse, crank it, get it started, then put the fuse back in.
2. Car breaks up at WOT, heavy fuel consumption, and strong fuel odor.
3. Signal Start, Pin 34 Orange wire is only getting 8-9 volts during cranking. I've traced this back to the ignition switch barrel.

What I have checked/replaced:
Spark - Good + new spark plugs
Injectors- Brand new Nismo injectors
FPR - I originally thought this was the problem, replaced it with an OEM one, but problem still persists.
Return line - Not clogged
Fuel Filter - Replaced
Fuel Pressure - When car is on, 37psi and 43psi with vacuum disconnected.
CTS - replaced
No Boost leaks
MAF - swapped with another one, issue still persists (verified 2x)
TPS - setup correctly (verified 2x)
CAS - setup correctly (verified 2x)
Timing - spot on (verified 2x)
Ignition Switch - New


Please share thoughts.


Appreciate the help.

Thank You

Update 8/26/2021:
Martin from RS Enthalpy helped to resolve this issue. I'd also like to thank Dboyizmlg for his help and getting on the phone with me numerous times to troubleshoot. We figured out that the ECU is not getting enough power during startup. We came to this conclusion by doing the following tests:
Test 1
1. Unplug Start Signal connector on the Starter.
2. Test Pin #34 - received 12.3 volts
3. Plug Start Signal connector back
4. Test Pin #34 - received 8-9 volts
Conclusion - too much load when the starter kicks in, not a big enough power wire. Turns out, since my battery is relocated, previous owner used too thin awg of aluminum wire.

Test 2
1. Test Pin #36 (ign. switch) & Pin #38 (ECU Power) - received around 9 volts
2. Supplied direct 12 volts to both these pins
3. Cranked the car and it started up instantly every time
Conclusion - this would explain the erratic start up. As some times the power wire was able to supply the voltage due to load changes.

[Mikester]

For fear of sounding like a smartass...your AFR gauge is connected to your headlight switch, is your fuel pump wired properly? Legit just wondering, no disrespect intended

Mike

[ZenkiDK]

No worries...Yeah, when I got it installed, they wired it so that it turns on when I turn the parking lights on. TBH, in this situation, how its wired came in handy cuz I was able to see AFRs during engine shutoff.

As for the fuel pump, the car has been running on this fuel pump since 2016, so yeah, I believe its wired correctly.

[xpinoyxmk]

Ecu board may have fried and the ecu goes into a safe mode.

Happened to my rs enthalpy board after 4 years one random day.

Good luck.

[ZenkiDK]

Still happening...

[ZenkiDK]

bump...still need some help.

[ZenkiDK]

bump, edited the post based on new findings..someone please help.

[Kingtal0n]

1. Wideband MUST be running when engine is running. If you run the engine with wideband OFF it will ruin the sensor. Just FWIW

2. It goes:
Maf -> ECU -> Injectors

These engines are very simple. You check compression, fuel pressure, boost leaks, timing.
And then it boils down to maf placement, injector size and ecu tuning, wiring.

If the issue appears from no where you should be able to correlate some behaviors,
i.e. dropping fuel pressure with increasing AFR on wideband
or boost leaks or maf wiring issues with AFR behavior

Always watch the wideband because it will basically tell you everything you need to know since timing is set by the CAS and never moves and compression wont change unless a piston breaks

[ZenkiDK]

Thanks KingTalon for the reply.

What would cause a weak voltage to the Start Signal wire on the ecu? Would it be coming off the ignition switch?

[jedi03]

correct...what i have seen alot of other vehicles do is add a relay to that specific circuit so it needs nearly nothing to properly activate it

[Dboyizmlg]

I believe you are over thinking the issue...

I am pretty confident that your issue is in the fuel system... not wiring related.

Have you checked to see if the o rings on the injectors are leaking?
Are your spark plugs fouled with fuel (if so how many sparks plugs).

I have seen the issue of in-proper installation of injectors cause fuel to run down the bottom o ring and causing fuel flood issues.

Check and verify that first, also church to see if your fuel rail is bent or kinked... I have seen these a couple times in SR’s

Shoot me a PM and I will be able to help you out more if issue continues

[Dboyizmlg]

Messaged you! Let me know

[ZenkiDK]

Update

msglength