L83 swap into scout ii

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09-20-2022
jrodyoung80

L83 swap into scout ii

Hey guys, totally new to the LT platform. I'm boggled over the amount of discrepancy on fuel pump and control information on the webs/forums.

Here is the dilemma. I've swapped a low mile L83/6l80 into our 1978 Scout II. We are using a Howell harness and ECM. Everything is plug and play and really easy. Except when it comes to supplying fuel.
We started out with a Walbro GSS342 pump and ran it returnless. Had the inline pressure sensor up near the engine. FPCM is mounted on the firewall and plugged in. The tune is set to be controlled by the FPCM like
the original engine was in the truck. Would not start or run. Truck would run with injector cleaner being sprayed in the intake but that is it.

Reading online, we have the wrong fuel pump installed. This is where we swapped to an OEM pump from napa and made it work inside of the Scout tank by removing the pump from the assembly and installing it in the Scout
assembly. We also added a Aeromotive Fuel Pressure Regulator on the firewall and a return setup. We are getting a solid 72psi out of the regulator and still will not run unless we are spraying in the intake.

We have went over every connection and plug on the harness.

Yes there is an inline filter and it is new. All -6 hose on the system.

Does a new FPCM need to be programmed to the system or will it work correctly right off the shelf?

What would you recommend we do about fueling issues? I'm leaning on something not being right with it and I'm not against starting over with the fuel side completely.

Should the whole FPCM be tuned out? Or is it even a possibility?

All help is appreciated.
09-20-2022
shonuff53

I didn't run the fpcm and am fine with the 58psi from the vette filter/regulator. you might be dealing with a different issue. Always run extra electrical power when first starting and get the rail pressure up. Did you already try pulling codes and data logging everything with just electrical power?
09-21-2022
jrodyoung80

Quote:

Originally Posted by shonuff53

I didn't run the fpcm and am fine with the 58psi from the vette filter/regulator. you might be dealing with a different issue. Always run extra electrical power when first starting and get the rail pressure up. Did you already try pulling codes and data logging everything with just electrical power?

I did, it has been a minute. I will get them pulled again today and post them up. I have a borrowed HPT and a regular hand held code puller. Nothing fancy.

I'm not sure I understand the extra electrical power.. As in having a charger on the battery?
09-21-2022
shonuff53

Yes, charger or jumper it to a running car
09-21-2022
mbray01

Not sure im following, you have 72 psi fuel pressure, but trying to figure out why pump and/or module isnt working.
Sounds like your chasing the wrong end, if you have 72 psi fuel pressure, then the module and pump are working
to me it looks like injectors are not working, probably due to vats not being properly disabled to run stand alone
09-22-2022
jrodyoung80

Quote:

Originally Posted by mbray01

Not sure im following, you have 72 psi fuel pressure, but trying to figure out why pump and/or module isnt working.
Sounds like your chasing the wrong end, if you have 72 psi fuel pressure, then the module and pump are working
to me it looks like injectors are not working, probably due to vats not being properly disabled to run stand alone

VATS is off, I resent the ECM to Howell to confirm everything was correct. Definitely have 72psi at the regulator. Where it goes or what happens from there is what has me stumped.
09-22-2022
Shrek

Please list the DTCs that are being set (or pending).
09-22-2022
jrodyoung80

Quote:

Originally Posted by Shrek

Please list the DTCs that are being set (or pending).

P0192 - Fuel Rail Pressure Sensor A Circuit Low Input

P0315 - Crankshaft Position System Variation Not Learned

P057C - Brake Pedal Position Sensor Circuit Low

P127C - No DTC Definition Found

P2535 - Ignition Switch Run Start Position Circuit High
09-22-2022
Shrek

Quote:

Originally Posted by jrodyoung80

P0192 - Fuel Rail Pressure Sensor A Circuit Low Input

P0315 - Crankshaft Position System Variation Not Learned

P057C - Brake Pedal Position Sensor Circuit Low

P127C - No DTC Definition Found

P2535 - Ignition Switch Run Start Position Circuit High

Thank you for posting the DTCs being set - that was very helpful.

DTC P127C is Fuel Rail Pressure Sensor 2 - Low Voltage.

In a custom vehicle (Hot Rod) conversion ALL of those DTCs should be set to "Not Reported". Howell Engine Development builds an esthetically pleasing wiring harness, but module programming is not one of their strengths.

These active DTCs may (or may not) be the cause of your no start condition - but they are certainly not helping your situation.

Fuel pressure anywhere between 58 PSI and 75 PSI should work just fine - however, this will also depend on how Howell configured ECM parameters 7030 through 7035 in the E92 ECM calibration.

Gen 5 conversions are extremely unforgiving regarding what all may contribute to a no start condition.
09-23-2022
jrodyoung80

Quote:

Originally Posted by Shrek

Thank you for posting the DTCs being set - that was very helpful.

DTC P127C is Fuel Rail Pressure Sensor 2 - Low Voltage.

In a custom vehicle (Hot Rod) conversion ALL of those DTCs should be set to "Not Reported". Howell Engine Development builds an esthetically pleasing wiring harness, but module programming is not one of their strengths.

These active DTCs may (or may not) be the cause of your no start condition - but they are certainly not helping your situation.

Fuel pressure anywhere between 58 PSI and 75 PSI should work just fine - however, this will also depend on how Howell configured ECM parameters 7030 through 7035 in the E92 ECM calibration.

Gen 5 conversions are extremely unforgiving regarding what all may contribute to a no start condition.

Thank you @Shrek for the insight. Do you have a good lead on someone I can send this ECM to so I can have that issue resolved?
09-23-2022
Shrek

I am not from your area - Texas is a big place - there must be some reputable tuners available.

Dyno tuning facilities are great at dialing in the airflow model - but are generally not overly knowledgeable regarding the intricacies of a conversion project.

The "best" solution for you, is finding a knowledgeable tuner who makes "house calls".
09-23-2022
jrodyoung80

1 Attachment(s)

Here is my tune file, I messed with some MAF values I read from YouTube. Probably all wrong lol.
09-23-2022
jrodyoung80

1 Attachment(s)

I have attached the log file for reference.
10-04-2022
castorjames

make sure your swap has the correct high pressure sensor for your app. 3 pin vs 4 pin. double check the 2 connectors that goes behind intake. they can be mixed and will make this issue