Starts up then begins to run rough and dies

[XfireZ51]

Went to take Z out yesterday for a quick run. It had been out a few days prior w a datalogging session. No problems. I have an Ostrich 2 emulator in the car. New bin, car wouldn’t start. Re-load, same issue. Replace Ostrich w flash prom, car starts using previous bin file but get a Code 41. Flash prom w new bin, car starts but begins to run rough then dies. No code.
I check FP, static w ignition ON jumps to 50psi then drops to 40.
Nothing changed except for loading new bin in Ostrich. With the new build, I’ve been working on refining VE table as well as setting timing now that I don’t have knock. Car has been running great. New bins flash SES w ignition ON as they should. ECM flashes Code 12 when in ALDL as it should.
Also compared the bin files and nothing appears out of whack from one cal to the other. My suspicion is fuel pump.
Discuss.

[Ccmano]

How long does it run before it goes rough and dies? What does the fuel pressure do it you pull the vacuum line on the regulator?
H
:cheers:

[XfireZ51]

How long does it run before it goes rough and dies? What does the fuel pressure do it you pull the vacuum line on the regulator?
H
:cheers:

It’ll run for a few seconds then start to stumble low idle, then die.
Haven’t pulled the vacuum line.
Haven’t checked fuel pressure w motor running. Need 90* elbow to get to rail pressure fitting for that.
I hear pumps with ignition ON.

[Ccmano]

I would test to eliminate the fuel pumps and filter first. Go from there. Especially since no codes are shown.
H
:cheers:

[XfireZ51]

Just checked MAP hose and regulator. Looks good.

[32valvZ]

Any chance the IAC is sticking at some point?

[lfalzarano]

Fuel pressure regulator?


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[XfireZ51]

K got it. I think the ports on my laptop are going bad. Not downloading bin files properly. Reloaded Ostrich w different cable and motor was fine. Also checked w flashprom and that worked.
Laptop not recognizing USB devices on the ports I am using.

[lfalzarano]

Time for a new laptop. Make sure it has solid state drive(s). Don’t chinz out on the memory[emoji512]


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[XfireZ51]

A netbook would be fine. The bin file is 32k.

[lfalzarano]

If that’s all you use it for...


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[Dynomite]

Fuel pressure regulator?

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A guy near me here in CA called me about a ZR-1 that he was selling but with the same symptoms you have.....would not run.....sounded like it was flooding each time he started it. As I recall there was even raw gas in the plenum.

I worked under a floodlight after dark in his driveway for a couple hours (had to drive back and forth to my place for an operatonal FPR and some tools a couple times) :p

I replaced his Fuel Pressure Regulator and it fired right up and he happily drove it around the block.
He thought he would be stuck with a non-operational ZR-1 forever :D
I told him NO CHARGE but he gave me a NEW Set of Mag Wheels he did not install on his Truck he was soooooo excited ;);)

This was before Phil invented the "Modified Fuel Pressure Regulator" that can now be replaced without removing the plenum
:thumbsup:

I now have Phil's New Modified Fuel Pressure Regulator on ALL LT5s and even have a couple extra for a crate engine and rebuilt LT5 on the bench. It is just one of those modifications I do to ALL ZR-1s along with my standard LT5 Initial Reconditioning (Starter Solenoid, Valley Drain, New Secondary Vacuum Syatem, New Fuel Filter, New Charcoal Canister, refresh of INFL REST grounding, New 180 deg Thermostat and Aluminum Radiator ......and Blocking TB Coolant and other things including new Injectors as required and custom Haibeck Chip) :p

Once the LT5 is refreshed it will run forever with no Codes

Oh...almost forgot.....got to have Carter Bling on ALL ZR-1s :thumbsup::thumbsup:

Post 281 - The Improved LT5 Fuel Pressure Regulator (https://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-15.html#post1596384563)
Post 282 - Changing Out Improved Fuel Pressure Regulator (IFPR) (https://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-15.html#post1596384571)
Post 283 - Phil's (Jagdpanzer) Fuel Pressure Regulator Solution (https://www.corvetteforum.com/forums/c4-zr-1-discussion/3005470-tech-info-lt5-modifications-rebuild-tricks-500-hp-15.html#post1596384578)