Hey guys, I spent all last summer battling fuel issues on my newly built 350 tpi. I thought I had it all figured out after doing 24lb injectors and a newer fpr at the end. The car started easier and would idle with no problems, now I'm back to seeming like I'm getting fuel running back to the tank from the rails or something. I haven't done anything with the car all winter but garage it. When I start it now, I need to rev it for a bit until it gets warm otherwise it dies. If I get it warm so it idles properly, then shut it down, I have the same issue still. Anyone have any ideas?

 

I was just thinking too, if I had a vacuum leak, would it react like this? I thought it would run a bit off even when it warmed up

 

Also today as soon as I put it in reverse it died a few times

 

Anything?

 

K thx baiiii

 

How's fuel pressure? And codes? When it runs, does it run smooth?

 

fuel pressure is still at about 40psi (harbor freight fuel pressure gauge so its hard to tell if its 100% accurate), it doesnt run any codes. since basically all the emissions stuff is gone i dont know if it can find any codes to throw haha. it runs smooth after it warms up. when it just starts it has some issues staying running, i have to gradually press the gas pedal down until i rev to about 3k and then it seems to idle ok. if i try just mashing on the pedal it sounds like it starts choking out and tries to die, it sounds almost like it only hits on a couple cylinders so i'm assuming its not getting enough fuel in from the start.
last summer i found out i had a bad fpr and it cause the system to de-pressure each time i shut it down, i havent had a chance to test it again, but at the close of last fall it was still operating properly.

 

just gonna get an afpr, and eventually going to do full roller rockers. see if that helps. thanks guys

 

how about your IAC valve?

 

You might raise the fuel pressure if you have an adjustable fuel pressure regulator to see if that helps. 24 lbs hour might be draining the fuel in the lines quickly, or upgrade the pump if that becomes the issue. Also, new fuel filter?

 

i wonder if it could have anything to do with the problem. the plug has somewhat broken, but i thought it was just the weather seal part. i know it worked find when it was in the 305 so i figured it would be fine in the 350 too. is there any difference in parts due to motor size?

i had put on the SVO 24lb's first, turns out they run at 32psi, whereas our system runs at 41psi so the pressure turned them into 26.5lb injectors, but the fuel pump was able to keep up. when the motor starts and i stomp on the gas it kinda starts to bog down, but if i slowly rev the motor up to top rpm then it doesnt bog down. once the motor warms up then it runs fine, but until then it wants to stall

 

sounds like your flooding the system. were your injectors purchased new or are they used? any black smoke until it warms up out the tail pipe thats a sign of being too rich. thirdgens ran rich with 22# injectors so 26.5 is a bit much

 

they're re manufactured bosch injectors from southbay. i got rid of the SVO's and put the original fpr from the 305 back in (had a new diaphragm in the fpr for the 350 which caused problems). i havent seen any smoke at all on startup, or during revving. even with the stock 305 tpi it always smelled rich so i havent noticed the smell being much worse. i put 24lb injectors in now, it was recommended to me to put the bigger injectors in with the engine upgrades i had done.

 

I would check throttle setting, IAC, TPS, look for any vacuum leaks, and it might not hurt to check the tank for any issues (maybe something is clogging the strainer?).

 

ive gone over it a couple times looking for vacuum leaks, the only one i can find is a larger vacuum line to the throttle body (i think its part of the idle air control, not sure) is kinda rotted out where it connects to the throttle body, other than that i have all new vacuum lines on it, and theyre all attached. the fuel pump and strainer are new as of a few years ago, since then its become a weekend warrior and not a daily driver anymore (had to have the fuel tank soldered since the fill neck cracked). the filter is brand new since the motor rebuild. i'm going to try and check the iac when i get a chance with my whole kitchen renovation project going on too. i'm kinda hoping i dont need to downgrade the injectors, i figured with the engine upgrades it would support the bigger injectors like i was told to do. plus i dont want to rip down the fuel rail again, even though i guess i'll have to in order to install an afpr

 

lately having hard starting issues again like i was at first. like i need to crank over the motor for a long time till it starts. almost like the fuel system is draining back. last time it was the fpr, this time i guess i'll get an afpr and try that

 

not sure if this has died out, but i got the car on the road finally again yesterday to toy around with. it hardly started, needed starting fluid then started right up, it puttered at first then it just kept cranking. no issues with the starting fluid, almost like the plugs werent wet, like there was no fuel in the system. when i go to take off before its fully warmed up with driving for like 10 mins, i hit the gas and at low rpms it pops in the exhaust, not as loud as a full blown backfire, but can feel a pop and a stutter quickly. as the rpms increase it runs fine. not sure if you guys have any thoughts on this.