i have a 91 z conv with scroggin dickie 350 vortec TPI. today i bought a fuel pressure guage from auto zone and hooked it up to adjust the pressure.

when i turned the ignition the pressure went up and the back to about 37psi. then i started the car and things got interesting.

with the car started the car the guage jumps WILDLY back and forth between about 35 and 55psi at idle. this thing looks like mexican jumping beans on speed!!!

is this normal?????

how the hell can i set it if i cant read it?

the car seems to run ok, but i wondered it might be a problem.

thanks

 

no it's NOT normal. there a test proceedure floating around in the archives. try a search. it should NOT fluctuate THAT much. it could be your FPR or fuel pump that may have a problem.

it may very well be your FP dying on you since the FPR has been replaced not to long ago.


edited: too early in the morning. sorry for the confusion.

 

"no it's normal" & "do it should not fluctuate that much"

which is it??????????????????

afpr is the fuel pressure regualter, right? it was installed new on the engine about 10k miles ago.

 

oh come on, someone must have used a fuel pressure guage!!!

please gimme some ideas!!!

 

so how much fluctuation is allowed?? when i hooked up my gauge the needle kept jumping about 10 psi back and forth. then other times it would be less.

 

With vaccum off the gauge it should not bouce.

Hey Slo

Ever get that Superram on?

 

i havent messed with it, i just read what someone posted on the board one time..


the injectors open and close, and cause a "pulsing" fuel pressure...

there was somthing hooked up (NOT THE FPR) that absorbed or stopped the pulses.........

 

well since u won't try a serach neither will i. it has been covered before and i cannot remember the reading off hand. do a search and compare to other users reading. usually no more then 5-10 psi max at WOT. best of luck. i believe vader helped cover it?

 

first things first, i did a search but did not find what i was looking for. i will look for vader post.

vacum off the guage? would you please explain that.

if i cannot get the bouncing to stop just i just approximate the setting?

not yet on the super ram....nice to have a few hundred sitting around the garage!! i have just been real busy with business etc.
hopfully in the next couple of months.

not to bore you too much, but i just won a custody case for my kids, praise ***!!:hail:

thanks

 

it is suppose to say praise ***, dont know why it bleeped it out.

 

hmmmmmmmmm how bout G o d

 

Are you trying to read the pressure at idle? If so pull the vaccum line off of the regulator and then check the pressure. The pressure you read will be your desired WOT pressure. All other times your pressure will be less or slightly less due to manifold vaccum, give or take, the reading should be steady. If its not steady something is amiss: pump, filter, gauge, regulator, injector.

Edit:

Congrats in court! If your ever in AZ bring the kids by uncle OMINOUS and Ill take em for for a ride in a nasty fast car, LOL! The Formula is alive and the 385 is thumpin, real hard!

 

i've been doing searches ever since i put new intake stuff on my car and it started to stall. i realize if i dont put "yes i searched" as part of the topic, no one will try and help.

if i cant find somethin, i post about it. if i do, then there's no need to.

with vacuum off the needle on my gauge still fluctuates. so engine vacuum isn't affecting it. im gonna end up replacing the injectors anyways after 2 so far are reading about 30 ohms.

 

pardon me but, i thought everyone did a search before posting questions. my mistake, i guess.

ya, it was at idle, i will try the vacum disconnect. tanks fer da tip!!

what kind of pressure are you running, if you dont mind me askin.
i am trying to set mine at about 50psi, which according to the tpis book seems about right.

thanks for the offer about me and the kids!! i am afriad the only doing any traveling anytime soon will be my attorney!!! whew, she didnt even give me a smoke with the bill.

if ya ever get down over here to dixie, lemme know.