frcefed98

iTrader: (16)

At my ends wit here...and my wallets not a happy camper as well

My fuel pressure keeps dropping as the car goes into boost or WOT and I have been suspecting my Aeromotive Fuel pressure regulator(boost referenced) as the culprit BUT

I went ahead and upgraded my
Fuel lines -8an feed, -6an return
Dual Walbro 255lph hi pressure pumps
Y blocked into a -8an bulkhead fitting in the tank
GM issue convoluted tubing from the pumps to the y block(no swelling intank rubber hose here)
and high flow fittings throughout....based all this off of Mightymouses fuel pump set up.

I've kept my
Racetronix plug and play harness from my racetronix 98 fuel pump set up(wicked nice harness...won't part with that, checked out fine too FWIW)
Speed Inc fuel rails
60lb Mototron injectors
Aeromotive Boost referenced regulator
Dynotune Digital Fuel Pressure Gauge

At idle my fuel pressure tries to maintain 58psi but fluctuates from 58psi down to mid 30psi...with the occasional drop down to 11psi At idle

Under brisk acceleration going into boost FP is at 58psi then goes up with boost for about 5psi then just tanks and will go down to 0 if I left my foot in it.
All vacuum sources also checkout fine.
So any advice?
J

V6 Bird

iTrader: (15)

What are you basing these numbers off of? A gauge with a sending unit or a true manual FP gauge...Im goign to say your sending unit is bad on the Cockput mounted one and you just spent alot of wasted money!

Screw in a manual gauge with a piece of braided line onto the fuel rail and tape it to the windshield do you can watch it as you are driving down the road...

frcefed98

iTrader: (16)

Wrong, and it was money well spent, upgrading the fuel lines when wanting to push a lot of boost is always a good thing, dual intank walbros too....


Wrong on the digital fuel gauge as well, its a great piece, the FP drop off goes hand in hand with the car falling on its face when this happens. If the sending unit was just the "bad" piece the car would still accelerate fine, and my a/f wouldn't go lean on my WBO2....

FP tanking=acceleration and a/f going to ****.

Money wasted on upgrading a fuel system....maybe if the car was stock it'd be a waste, but I'm far from stock.

And no the car isn't vapor locking, as the closest a line gets to a heat source is about six inches and we have the metal heat shield covered in self adheasive fiberglass heat shielding and the fuel lines are covered with heat shielding as well.

Armageddon

iTrader: (41)

dude, im having the same problem... it just started all of a sudden too. I noticed the car wants to lean out when it makes any kind of boost. No vacuum leaks. I'm running a big external Weldon pump. Fuel pressure is 60 idle 70 under boost and wammo instant lean... lean pop stutter, I lift before it gets real bad, but it's starting to get frusterating. I'm also running 60LB Motorons. I was wondering if one of my injectors wasn't flowing properly... It's starting to get on my last nerve.

disassembled

iTrader: (3)

Is there any you could watch your duty cycle or have you watched your duty cycle when this is happening? What haven't you tested or replaced in your setup? FPR? The CAS one is like $130 from speed inc. Did you have all similar components when you had the D1SC? Have you checked your voltage at the pump? There's something that's obviously wrong and sounds electrical if you're getting this problem at idle as well as under load.

Does the harness run off of the altenator? How old is it?


Greg

Armageddon

iTrader: (41)

mine idles fine, maintains excellent pressure, until boost.

V6 Bird

iTrader: (15)

Hey i was just throwing ideas out there...But the problem truly is, regardless if the car is falling on its face, you still havent narrowed that sending unit out on its reliability yet. ive seen more of those off many electronic ones off more then any that ive ever seen mechanical.

Id start with the cheap things to replace first though and replace all vacuum lines in the setup since its SUPER cheap on your pocket book. too bad you cant check voltage at the pumps on WOT blasts though that'd be a big help!

V6 Bird

iTrader: (15)

also have you tried unplugging the vacuum line off the regulator to see if fuel sprays out of it when you rev it up or at idle...It could have a ruptured diaphragm.

Mike

disassembled

iTrader: (3)

You have two very different problems. He can't even stay consistent ever, you can. What brand of regulator are you using?

Greg

Armageddon

iTrader: (41)

I agree with the ruptured diaphram theory. I think my issue is more than likely electrical. MAF most likely.

CAT3

iTrader: (9)

frcfed...I say your regulator is toast...WTF would you go into boost is your lsosing pressure at idle man? C'mon now, dont burn that engine up so soon.

Slowhawk

iTrader: (12)

On all the boosted cars I do,we DO NOT use the vacuum port on the regulator.For some reason it make more of a headache. Just set fuel pressure at 60lbs and go from there.

How is the battery voltage?Grounds? With pressure dropping under load I would suspect pump pickup's are sucking in air or the voltage is dropping to the pump's..Maybe the pumps are sucking against each other?

For reference we ussually run 650-700rwhp from a single intank Walbro(hot wired) and the fuel system you describe Also we run the hot/ground directly to the pump--skipping the bulkhead connector.

frcefed98

iTrader: (16)

Cool tons of ideas here,
V6 bird, sorry bud you've always been cool with me I was just a lil frustrated when posting about this on going problem. Believe me I tried all the cheap stuff first

No gas out of the boost ref port....tried that already.
Fresh vacuum lines, and vacuum caps too...cheap and easy to replace all that

Armageddon, this problem has been messing with me for a while now, it started on my last run at the track with the ATI D1 still on the car, switched to the turbo and nothing change Thought it was just a glitch.

Charlie, you know me better than that, I'm running the car super rich till I iron out this problem...this allows me to go into boost just enough to see the FP drop my a/f is set to 10.5 at WOT, and falls to about 12.1 when I get out of the gas...I'd kill myself if I popped this fresh engine so soon

Slowhawk, man you always help me out
Well we tested the racetronix harness, with it on the car the FP drops, with it off and the car running off the stock harness...same... FP drops

It was doing this same thing with my single racetronix pump, stock lines too, so I upgraded to the dual intanks with -8an feed, and -6an return with high flow fittings and filter throughout. Even with the tank completely full of gas, it makes no difference, FP drops like a rock.

I'll forgo using the boost ref port with the new regulator thats on its way.

All the grounds are fine as are the electric connections...no breaks, shorts...everything works just fine on the car...no popped fuses...nothing
Its the strangest damn problem i've had with the car.

New things i've done the car so far
02 sensors
plugs
plug wires
MAF sensor
Vacuum lines and caps
New fuel lines
New dual walbro pumps
New intank filters
New high flow race inline filter
High flow fittings
heatshielding anywhere I thought heat would bug the lines

Only thing not replaced....Aeromotive FPR.
J

slowpoke96z28

iTrader: (2)

i'd say regulator if its not an injector/injector driver staying open. most likely regulator. i know you verified your electrical gauge as good, but once this problem is repaired, i would break out the mechanical gauge and verify the system is maintaining 60 psi at various RPMs. verify it with no boost, then if its good try it at low boost and creep up until you are at your normal boost.

frcefed98

iTrader: (16)

I can do that, Thanks

V6 Bird

iTrader: (15)

There's one thing that does puzzle me and this thing happened to my buddies Prcharged stang (8 Sec @170+)

On the 1-2 shift the car would die, glitch like it ran out of fuel. Similar to what you are describing but not to a T. He replaced it ALL like you did. We never could believe what it was though and we did eventually find it. it was all in the tune amazing enough. The tune being too fat on the FAST it shut down for the shift and would come back. He would have to peddle the car like this to get it to recover but still won alot of races like this...He did race FFW for the longest time and now hes running Clash races last I heard. When he talked to ACSD about the deal he was having (his sponsor for his Procharger setup F-2r) tehy took the car and went over tune on it with him and leaned it out to 11.5- 12.0 under boost and it never had that issue again to this date. Im only blabbering right now to help tickle your brain with ideas. Not saying this is your issue, but giving you an idea of what we've gone through on his car as well and what the solution was. DJ re-wired the WHOLE car, ran all new parts, (warrantied thank God) and still had the same issue. Never once thought the tune was off until they went over the tune and tweaked and it all went away! True Story man. take it how you want.
this is a 7 second car in good air at 180+ easily. 12.0:1 AF is kinda high for my likings too but thats where these guys run their blower setups...I cant imagine a turbo setup not liking that either. Post up what you find.

frcefed98

iTrader: (16)

Might be the tune, me and hellraiser were throwing that around in PM's....maybe something isn't jiving in the tune. I'll go back over it and load up a new tune if something stands out in the fueling tables.....never know, it could be forcing the injectors to dump. Something to log tomorrow on the way to work.
Thanks man,
J

DeltaT

iTrader: (5)

Have you checked the system volume hot? You might get a 5- gallon jug and get everything warmed up then route everything from your engine compartment into the jug. Time it to see how long it takes to fill to the 3 gallon mark, and make sure it matches what you expect.

Jim

PS Where does your return line dump to? You should have it a ways from your pickups. Also you can get vapor lock just from the heat of twin pumps recirculating a lot of fuel. Do your lines get hot after a run? Worth checking. Try running with a full tank and see if it makes a difference.

frcefed98

iTrader: (16)

full tank makes no difference, I never run less than half a tank with my dual walbros anyway thats a big no no.

The volume is there, when running the new lines I had my brother hold the feedline into a five gallon bucket while I primed the system to clean out the lines of any debris that might have got in there when we installed em. It was like a fire hose

Return dumps into the tank in the same location as many others that run there dual set ups this way no different.

Besides ...

This was happening with the stock lines, single intank pump

I replaced the lines and intank with bigger lines and dual intank pumps to try and get rid of the problem, the problem still persists.

The only thing that hasn't been changed it the FPR, which will be replaced as soon as it arrives from full throttle speed.com

I messed with my fueling tables today, nothing problem still plagues me.
J

MECHAM

iTrader: (4)

i bet your FPR is leaking