Question on fuel pressure>> - ZR-1 Net Registry Forums

-=Jeff=- · 05-19-2008

okay..

I checked the Fuel pressure on my car last night. I shut it off areound 8pm from the test drive. I hooked up the fuel pressure gauge around 10pm to check.

Ignition key one, engine not running, pump primes to around 48psi, then steadily falls down and sits at 20psi (falls down over the course of a minute)

this am I went out there pinched the return line hose, key on, engine not running, pump primes to 48PSI and settles at 44PSI.. I repeated the SAME steps as but without the return line pinched with the SAME results.

so why the fall of when the engine is warm, but not when it is cool?

guinnessdood · 05-19-2008

Quote:

Originally Posted by -=Jeff=-

okay..

I checked the Fuel pressure on my car last night. I shut it off areound 8pm from the test drive. I hooked up the fuel pressure gauge around 10pm to check.

Ignition key one, engine not running, pump primes to around 48psi, then steadily falls down and sits at 20psi (falls down over the course of a minute)

this am I went out there pinched the return line hose, key on, engine not running, pump primes to 48PSI and settles at 44PSI.. I repeated the SAME steps as but without the return line pinched with the SAME results.

so why the fall of when the engine is warm, but not when it is cool?

Sounds like you have injectors that are leaking when they are warm. Do you still have the stock injectors in your car?

-=Jeff=- · 05-19-2008

Quote:

Originally Posted by guinnessdood

Sounds like you have injectors that are leaking when they are warm. Do you still have the stock injectors in your car?

no they have been changed.. I need to get the car warmed up and then test again with pinching the return line..

if I had 16 good Multecs I would try those to see if it is better to rule out injectors.. but out of the 16 i have I might have 8 good ones

is it a typical failure for the injector to leak when warm?

now if the injectors truly are leaking, on a scan tool the BLM should drop as it is removing fuel due to running rich, right? I will check my scan again, but I don't see that happening on either bank. just trying to understand what might be bad

bradslt5 · 05-19-2008

wouldnt the fuel pressure holding @ 44 when he pinches the return line rule out the injectors leaking? what in the tank assembly would cause the pressure bleed down . i have the same issue on mone of my cars. even did a plenum pull pulled the injectors out so i could see them all and they hold fine no drips at all anywhere either top or bottem. so what gives?????anyone know

05-19-2008	#1
-=Jeff=- Join Date: Jul 2007 Location: Bartlett, IL Posts: 7,132	Question on fuel pressure>> okay.. I checked the Fuel pressure on my car last night. I shut it off areound 8pm from the test drive. I hooked up the fuel pressure gauge around 10pm to check. Ignition key one, engine not running, pump primes to around 48psi, then steadily falls down and sits at 20psi (falls down over the course of a minute) this am I went out there pinched the return line hose, key on, engine not running, pump primes to 48PSI and settles at 44PSI.. I repeated the SAME steps as but without the return line pinched with the SAME results. so why the fall of when the engine is warm, but not when it is cool? __________________ 1990 Corvette ZR-1 #1051 Watson Headers (2" Primary) - 3" Magnaflow Bullet cats - LT4 Catback Late Model IH - Plenum Coilovers - 4.10s Custom Interior NCM Lifetime Member #978

05-19-2008	#4
bradslt5 Join Date: Oct 2007 Location: lone pine and mammoth lakes ca. Posts: 544	Re: Question on fuel pressure>> wouldnt the fuel pressure holding @ 44 when he pinches the return line rule out the injectors leaking? what in the tank assembly would cause the pressure bleed down . i have the same issue on mone of my cars. even did a plenum pull pulled the injectors out so i could see them all and they hold fine no drips at all anywhere either top or bottem. so what gives?????anyone know