indirocz28

Asking for exactaly what the title says- Thanks!

84z28350

in a perfect world it would hold it indefinately...

TraviZ

iTrader: (2)

i don't think so. the fpr is just a pinched off line basically and fuel will bleed through it. i think after shutdown it should hold for a second but slowly and steadily drain down.

sofakingdom

iTrader: (1)

In the real world, any MPFI system, TPI included, should hold at least half of its pressure at least 6 or 8 hours; i.e. I'd want to see 20 psi minimum after 6 hours

Sonix

iTrader: (1)

now the main beef: why do you want to know? to solve a problem, or just out of sheer curiosity?

indirocz28

Well, i was talking to a guy i talk to on Yahoo about my car, and we were trying to figure out why my car- with all the mods and in theory should be fast, is so damn slow.


we were talking about fuel pressure, changing the filter, and how long the TPI system should hold pressure and if a filter didnt give me more power that i should adj. the cam timing 4 deg adv. He said he thought a system should hold it overnight b/c his buddies mustang has a FP gauge on the hood- and i said- well the TPI is a return fuel system- so it would make sense that it bleeds through though after shut off..

well- i changed my fuel filter today and got 5 more psi of fuel pressure at idle, but it still bleeds out w/in like 20 sec. to like 8 psi after shut down. - so i was curious if its possible that the LT1 injectors i bougt off a guy on here are bad and leaky...

Ive not noticed any more power gain from the new fuel filter, however i adjusted my TV cable to all the way tight, and that seemed to make a difference, but my car still doesnt fry the tires like he said his stock tpi 350 does. and i was like- yeah, something is up. and he was like " yeah" and i said " in theory- my engine should be making 300 hp and should smoke anything i see daily" and he said " yeah in theory" and i said "yes, but im not dealing w/ theory, im dealing w/ why have i put all this $ into this car and its still so ****ing slow"

anyone have any ideas? I've not adjusted the cam timing yet its set straight up at 0deg, and the Ignition timing is set at 6 deg adv.
all mods listed in side bar and signature
Thanks!
Jeff

Sonix

iTrader: (1)

more than...? what is your typical fuel pressure?


could be bad injectors. you're thinking of getting the car dyno'd, why not do that and find out where in the power band it's making power, and where it's not?

kind of a tame cam though...

joe350

Fuel pressure will bleed off unnoticably slow. If you are down to 8 PSI in 20 seconds then you definately have a leak somewhere.

indirocz28

it was like 45 on startup and 35 on idle, today it got 45 startup and 40psi idle..
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well, its not really 8.. its like 12.. but still

84z28350

Just FYI i hope you didnt actually pull the TV cable tight...

It HAS to be adjusted properly, if not you will loose your tranny in a real hurry!

Its not like the older TH350/400's which have a detent cable to initiate kickdowns, The 700R4 uses the TV cable to know what the throttle position is at and whats going on because it has not vac modulator!

indirocz28

well, it seems to shift like it's supposed to.. before the shifts were sloppy and weak, now they are firm and seem like it shifts the way Transgo said it should

indirocz28

I am kinda thinking that my injectors are kinda leaky.. i bought them off a guy here on TGO they are LT1 injectors.. but i dunno how old they are or anything, i know the car runs and fires on all cyl's but i think a couple may leak. and the car also backfires when i come out of being on the throttle hard.. ( ive only got a y pipe, 90 deg. bend and a muffler under the driveshaft tunnel until 2morrow when the rest of the exh. gets finished)

but a guy said that it could be backfiring b/c the injector is leaking and still feeding fuel through..???

thanks for any help guys!

TraviZ

iTrader: (2)

can u pull the injectors from the intake manifold but leave them in the rail, that way you turn on ignition. let the pump prime and see if any of those injectors are trickling any fuel?

xpndbl3

iTrader: (5)

pull the injectors from the intake and turn on the ignition to see if any leak out, if so you know your problem.

TraviZ

iTrader: (2)

i just said that :P

xpndbl3

iTrader: (5)

where should i mail your cookie to? for being quicker on the draw.

TraviZ

iTrader: (2)

don't sweat it. I'll pretend my next cookie came from you.

indirocz28

OK- i may try this..- Also- we figured out last night that im running a 88 Hypertech memcal w/ a zif and a prom burned for the ARAP bin from Tunerpro.net and im using an 86 auto computer- would this make a difference in power and timing and fuel???

TraviZ

iTrader: (2)

yup

joe350

Yeah, but not a difference in fuel pressure.

indirocz28

Well- the good thing is that - I've got about the right amount of fuel pressure..

what im trying to figure out here is why for all my mods- the car doesnt have the low end power it seems like it should.. and the whole thing about how long the fuel pressure should hold was just a question to see if i may have a leak...and i indeed think i might. but there are still other things to figure out- such as getting those computer spec's straightedned out.. I guess i need to get a MOATES adapter...

Anyone got anything else for me to try??