RE:Stock Fuel System Performance Diagnosis!

[polskifacet]

So you are comparing 12 volt output to see what the gpm is in a test set up to a running car which is 13.7 to 14.3 approx volts?

Shouldnt the running car get better pump output automatically?

From one of FoMoCo's the pump runs at 5 (or 5.5) and 12 volts which is controlled by the FDM.

Also there is more than enough fuel being supplied at 12 volts if it indeed gets ~14.1 volts.

[StealBlueSho]

Fuel rails maybe? There is a fuel rail pressure sensor too...

[polskifacet]

Fuel rails maybe? There is a fuel rail pressure sensor too...

How could fuel rails cause fuel pressure loss lol. Sensor is fine on the stock and 87/89 lms tune.

[StealBlueSho]

Only things left...

[polskifacet]

Only things left...

And the tune

[AJP turbo]

Only things left...

And the tune

I thought tune and strategy were ruled out long ago...you had 2 different calibrations from 2 different tuners that showed low fuel pressure when those same 2 calibrations are fine in other cars with the same strategy

[polskifacet]

If its not the pump which I should know in a couple hours, you think the ecu is janky? Doesn't make sense if it was only janky when tuned. After this, there is nothing else to test?!?

[AJP turbo]

Increased power when tuned puts more demand on the fuel system....dont know if its janky but i like that word....im of no help youve tested way more than i would have at this pointy

[TopherSho]

Increased power when tuned puts more demand on the fuel system....dont know if its janky but i like that word....im of no help youve tested way more than i would have at this pointy

Random thought, how does the pump 'receive' the signal and vary the output/pressure?   Does it use variable voltage?  Has there been voltage measurements on the line to the pump(s)? 

Also does the pump report 'back' its output?  And is that  return value wrong even though the physical pressure is good?

Crazy thoughts on allergy meds.. cheers

[polskifacet]

I hear you, hard to test all that with a doner SHO and oscilloscope. Also I get that hesitation when it drops real low so there must be something actually being funky.

[polskifacet]

Feel like its the same as my original pump. Curve is good but same as what I was getting at this temperature. I feel like LMS should make the tune fit my car at this point. What does it matter to them if I request adjustment.

[polskifacet]

I'll give LMS an ultimatum, adjust the tune or give me back what it will cost AJP to tune my car. Of course they will most likely do nothing. At least it will be noted that there is a fix and they choose not to.

[polskifacet]

I would like to offer my testing setup to anyone else that is having fuel issues. Pay for shipping and some kind of deposit and you can do what you have to.

[TopherSho]

I would like to offer my testing setup to anyone else that is having fuel issues. Pay for shipping and some kind of deposit and you can do what you have to.

watch that duct tape.  the Adhesive itself wont 'hurt the paint' but it will leave a funky residue if it gets HOT and it will discolor the clear coat over time.

[polskifacet]

I would like to offer my testing setup to anyone else that is having fuel issues. Pay for shipping and some kind of deposit and you can do what you have to.

watch that duct tape.  the Adhesive itself wont 'hurt the paint' but it will leave a funky residue if it gets HOT and it will discolor the clear coat over time.

Where do you see duct tape?