T/Atime

ive descovered that i no longer keep pressure in my fuel lines after i shut down the motor. so im assuming some of my injectors will need to be replaced.

so what should i do. buy a few used ones and hope i can eliminate my problem.

i dont plan on keeping my motor for longer than 2years.
ill be building a hsr, afr, 383 street motor in the near future. so i might try and find a simple solution because my little 22lbs injectors are only good to a point.

at the moment im at no more than 260rwhp. Can i use 24lbs ones or should i just stick with what i have.

88gta3508

yes... its is close enough to use your 24#... are you sure its the injectors leaking... the valve in the fuel pump.. is what holds the line pressure... the 24# Injectors will be a little on the small side for a 383.. also depends how involved your build will be...
you should look into learning to tune..

T/Atime

no im not sure my injectors are leaking. how do i diagnose this problem? btw i have a brand new walbro 255.

about the future motor i fully expect on buying brand new injectors and sizing based on hp levels. might need something close to 30lbs. but this is details in the future i will need to explore.

Aaron_SK

iTrader: (1)

Need to run a leak check on the injectors. You can do it any number of fancy ways. I always just pull the rail while it's still hooked up to the lines and set it on a cookie sheet covered in towels,then prime the system. Any leakdown will show up immediately.

24lb. injectors are NOT "close enough" to just swap in without chip work. You will be rich, lose power, and not be able to pass emissions.

88gta3508

he does have a tune... and he posted his Estimation way above stock...
PS a stealth ram alone will need 24 Pounds

T/Atime

thanks for the replys.
im running a hsr so its easy to pull my fuel rail so this will not be a problem. this might just have to wait till next year tho, getting so close to storing it for winter.

i dont have to undergo any emissions testing so not an issue. but i think i have nothing to gain by running 24lbs injectors. my tune runs great as it stands.

i know these 22 max out at around 300hp and i should be right in that area, lt1 would be 24lbs. with stock motors putting out 275hp.

88gta3508

slap in the 24's PS where did you set your base timing at

T/Atime

12deg, car runs great.

88gta3508

perfect I know 10Deg is just a starting point making power... 14 - 16 was awesome on my combo
the HSR loves timing

T/Atime

this is very true!! i had my car set at 6deg before i started messing around with it and let me tell you it was like night and day, or turning on a switch. very responsive, ive had it at 14 before and not sure i made anything more so i just put it back to 12-13deg

Aaron_SK

iTrader: (1)

These seem contradictory to me. If you are able to tune for larger injectors why not tune the timing table in the chip?

88gta3508

I'm not sure why he is running 22# injectors... you will need to ask.. PCM tuned i'm sure from his scan.... the 24# should be fine in his application
I tune so this would be easy... I had 30# in my combo and they were to lean

as for the base timing.... I have tried 100's of combo's with the HSR
it simply works best with the base timing set then play with your table

T/Atime

well, years ago when i installed my intake i just used all my factory stuff, tb, injectors, fuel pump, i had it dynoed at a local shop. the tech showed me i was running fat rich down low and leaning out in the upper rpms. untuned i had 252rwhp, other mods were just headers. so i sent out the information to pcm for less and they made me a chip.

since then ive installed 3" cat back flowmaster, removed the smog pump, made a homemade cai, replaced my fuel pump with a 255, msd distubutor and coil. kirban afpr. and last summer i noticed my car runs much better with more base timing. im not an expert on tuning but do plan on exploring this in the near future.

btw, the car was never re-dynoed after the tune so its just seat of the pants for now.

Aaron_SK

iTrader: (1)

Of course! Base timing is only used during cranking, and it should be set relatively low to get the engine to crank quickly. Then you dial in the chip to exactly what the specific engine wants.

Bottom line: ditch this hackjob mail order stuff and this tuning with base timing. Start burning chips. Stop guessing what the car needs, start running test to find out. Buying big injectors and dialing them down is no issue.

Just my two cents.

T/Atime

hey i totally agree, i thought it was worth mentoning above that ill be upgrading the motor in the near future. so for the time being guessing is alright with me.

if i had a built motor i would spare no expense in tuning, timing, pulsewidth, fuel pressure.....

FSTFBDY

iTrader: (33)

back on topic. do you have a FPG? hook it up and cycle you key on. It will built pressure when the pump primes. Does the fuel pressure leak down within seconds? or minutes?

Now pinch off your return fuel line. Do the same thing. watch readings again. Does it still bleed down to 0?

I have some good 24s if your on a budget and your problem is injectors.
Id look for some SVO redtops when you do the 383

T/Atime

yes i do have a guage on the fuel rail, i would say it drops down gradually to 10psi within 1-2min. ill double check tonight, and pinch the return line. ill post as soon as i have more answers.

T/Atime

i just tested the car and it leaks down very rapid, ive also pinched the return line and makes no difference. now to me i would think that pinching the return line has nothing to do with my problem. my regulator should keep all the pressure behind the rail.

now im thinking if i were to have a helper energize my fp and right after ill pinch the feed line to prove that its not my fp.

i will have to pull the rail by the sound of it like recomended above.

im doing these projects on the cheap, in the next few years. money is better spent on buying another house... bla bla bla

JekyllandHyde

iTrader: (3)

I have a buddy with a 92 Z28 who's fuel pressure drops immediately after shut off. He runs 36lb injectors in his nitrous ZZ4. I believe that the check valve in his fuel pump is faulty. It doesn't seem to affect his car's performance while driving and the fuel pressure shoots up as soon as the pump is run.

I'm running Ford Lightning 39lb injectors on my heads/cam/intake L98. They're doing really well.

88gta3508

That one way valve is not needed... I have a aeromotive external... They do not use that valve. Or most real HP pumps...

T/Atime

i energized my fp and immediately pinched my feed line to trap fuel pressure between pinch and regulator...

pressure did not drop at all.

what do i know for sure? my fuel injectors are not showing any signs of malfunction.

so theres not much else left, besides the check valve in the fuel pump. so is it needed?? by the sounds of it its not necessary.

My car starts great, runs and drives better then ever. i would have never known i had a problem if there was no guage on the rail.

FSTFBDY

iTrader: (33)

No, I wouldnt worry about replacing the pump at this time. unless your doing it yourself and have the time and resources to do it.

T/Atime

i can change my pump in 30min, problem is i just replaced it. should i return it??

T/Atime

whats the function of the check valve, its to maintain pressure when its not running eg. starting.

when its running, its not doing anything right? just an open valve?

FSTFBDY

iTrader: (33)

Im guessing you have a trap door cut out of the back hatch area. If thats the case and its only 30min. Id return it since its a New pump.


Correct.. typical problem with a fuel pump check valve failure is extended cranking time during start-up.(bad on the starter) What generally occurs here is that the check valve in the fuel line sticks open causing lack of fuel pressure untill you prime it a few times.

T/Atime

great thanks for the info!
i just emailed the seller describing my issue.

ive never returned anything from a mail order, do they usually warrenty items? i hope i dont have to send the old one!!

FSTFBDY

iTrader: (33)

Where did you get it from? Summit Racing / Jeggs / Racetronix ?? a company like that? or ebay?

If they dont you could prob do a extarnal check valve like aeromotive sells. (but you would have to adapt some 6am line / fittings
or something simple like this one.
http://djvmerchandise.com/pro1163391.html

T/Atime

thunder racing racetronix, w/walbro 255

88gta3508

I can't vouch for the Walbro Toy pump that gets re-branded for others
But my combo with a external aeromotive... No check valve.. would start instantaneously no hesitation...