Fuel injectors/Pressure ?

[LGAFF]

Last year I installed 2 new fuel pumps and new injectors, one set from SAP and the other Accels. I pressurized the fuel system and it jumps to 57lbs of pressure then drops to 41 and within 5 minutes pressure is down to 30 or less. I know Dominic had this issue earleir, wondering if the SAPs are crap and are leaking.

Times at the track are down fromlast year, MPH was down 2-3mph from last year. I was running 113-114.5 vs 115-117 last year.

LGAFF
92 ZR1
#234

[LGAFF]

Tested the Inj for resistence results as follows:

2ndry= 1)12.5 2)12.4 3)12.4 4)12.9 5)12.8 6)12.6 7)6.9:jawdrop: 8)12.4


Primary= 1)15 2)15 3)15 4)15 5)14.8 6)15 7)15 8)15


Hmmmmmmmmm


LGAFF
92 ZR1
#234

[Jeffvette]

Sucks, so which injector brand failed?

[Pete]

Change the damn injector,LOL
Did you go to Byron?


What as your 1/8 MPH
Was your 60ft the same as last time.

Did you make any changes to the car,chip tune, plugs,etc.

Pete

[LGAFF]

SAPs.... only 1 year old.......bought these off the bay. As I was nice enough to test these for the forum members please send your check or money order to Lee Gaffigan:D


Guess I know what I am buying next week.

LGAFF
92 ZR1
#234

[LGAFF]

Byron sucked.......

Started running 12.8s at 113, even realed off a 12.64. Speed was slow but that might be the injector. I think they worked out the timing issue both sides consistently sucked for me and 1/8ths seem consistent in MPH and times.

I was going to try one more run then a motorcyle engine blew just past the 1/8th....guy launched parts over the friggin fences on both sides. That was worth $25 right there. I got 8 runs in, could have done 12-15 but spent time trying to figure out what was wrong.

I might as well change the coils also. I wonder if SAP makes those

LGAFF
92 ZR-1
#234

[LGAFF]

I was running 8.3-8.4@ 89MPH on both sides fairly consistently. I was not getting the second half pull I am used to out of the car. I had the same issue when I went in early May. This also means my 391hp Dyno run was with a crap injector.

LGAFF
92 ZR1
#234

[LGAFF]

http://www.atlanticspeed.com/productcart/pc/catalog/accel_injector_new_free_t_1527_thumb.jpg (http://www.atlanticspeed.com/productcart/pc/viewPrd.asp?idcategory=2&idproduct=4836) Accel 150121 (8) "Only $259.88" #150821 21# High Impedence Fuel Injectors. Ford 86-95 5.0L, 96-98 4.6L, GM 86-92 TPI, 93-97 LT-1, ZR1 ZR-1 Ford (http://www.atlanticspeed.com/productcart/pc/viewPrd.asp?idcategory=2&idproduct=4836)
Price $259.88
ACCEL 21#* High Impedance FUEL INJECTORS #150121 (Set of 8) Applications: GM V8 1986 to 1992 TPI GM V8 1993 to 1997 LT-1 FORD V8 5.0L 1986 to 1995 Ford V8 4.6L 1996 to 1998.
http://www.atlanticspeed.com/productcart/pc/images/sample/pc_button_details.gif (http://www.atlanticspeed.com/productcart/pc/viewPrd.asp?idcategory=2&idproduct=4836)http://www.atlanticspeed.com/productcart/pc/images/sample/pc_button_add.gif (http://www.atlanticspeed.com/productcart/pc/instPrd.asp?idproduct=4836)

Are these the ones I need??


LGAFF
92 ZR1
#234

[Ccmano]

Line pressure down to 30 psi in 5 minutes? The spec. in the Shop manual is only to hold pressure for 10 seconds once the fuel pumps are shut off. Per the manual, the system should show 48-55 psi while the pumps are running with the engine off. When the engine is started pressure should drop 3-10 psi.

I don't think 5 minutes is relavent here. Sounds to me like your system is just fine.

Didn't you change your tune from last year? Change it back and see how it preforms.

Hans
:cheers:

[LGAFF]

Hans,

My manual says system should drop some once pumps stop but pressure should be maintained, however look at the test on the injectors, one at 6.8 and thats cold I would imagine once heated that one is toast.

LGAFF
92 ZR1
#234

[Ccmano]

Lee,

I don't think the system was designed to hold pressure for 5 minutes. Assuming the system is dropping pressure, both the in-tank check valve and the fuel pressure regulator valve leaking back can cause that as well as an injector. To eliminate the check valve pinch off the return line at the tank and see if there is a difference.

Low resistance on an injector doesn't mean it is leaking. It's does mean it won't pulse correctly if at all. However I would expect other symptoms like rough idle (if a primary injector) or a high rpm miss (if a secondary).

Other than poor times at the track were there any other symptoms? I think the next course of action would be to take a data scan of the system and see what tells you.

I'm running the Accels from Atlantic Speed and have had no issues. I think you have some more testing to do before you lay out the cash for a set of injectors.

Hans

[LGAFF]

Summit lists 2 injector sets=

Accel
1)150824: 24lb injector

2)150826: 26lb injector


Which set is proper for secondary injectors????? I know Atlanic Sells a set for 150121 that is universal, but is one of the above sets better?

LGAFF
92 ZR1
#234

[tccrab]

Those will probably run too rich. Our systems were designed around 21lb injectors.

TomC
"Crabs"

[XfireZ51]

Those will probably run too rich. Our systems were designed around 21lb injectors.

TomC
"Crabs"

They'll run rich unless you make a change in the calibration. ;)
Even then you may need to tweak the VE tables.

[Aurora40]

I don't know that Accel rates them at the same pressure as GM does. But I'd think get whatever # rating most people get, as they seem to work with no cal change.

FWIW, mine will hold pressure for 1/2 hour or more. Though yeah the manual doesn't suggest it has to in order to work properly.

You think the injectors are bad vs just one that was defective? I guess it's the same effort to change one as to change 8 though if you think they aren't a good product.