Well the new issue is fuel. does anyone have a tune with 42's and a 306 cam that I can look at. this thing is running strange, fuel pressure is at 42 running when I turn it off it drops to 20psi with in 30 min...... cked the fuel injectors no drain, changed out the FP reg with the factory one. the only other thing I can think of is the fuel pump I put in the walbro 255. the car will start fine the first time of the day run ok but rich shut it down and have to put foot on throttle to get it to start back up and will die if I try to drive it. I put a new coil on it MSD and removed the 6AL just to see. it dont sound like it has any misses just rally fat, the furl trims are running at 130 r and 125 lft. I havent ran the data log as of yet but am going to after I pull the tank and put the factory TPI pump back in it. I am also going to look at my tune to see if I can find anything. the o2's seemed to be working right jumping from 50-600mv. I did notice that the IAC was at 97-100% ????(used my hand held scan tool) TPS was reading right so it isnt that. Any help would be appriciated. Oh yeah another thing is the pressure will not drop to 0 with the FP relay unplugrd stays at 10 and will start and Idle crappy but will run???????? When I pull the relay the pressure drops and the car will die, but will start back up and idle with no fuel pump running?????

 

Looks like you and I are having the same sorta the same problem. Do you have an adjustable fuel pressure regulator? Did you get the computer reprogrammed for the 42lb injectors and the 306 cam? Before the 383 project were you having any hesitation or starting problems? I doubt that the fuel pump would be causing your problem. How much horsepower do you think you have?

 

yes to all the above, but put the factor FP regulator in for troubleshooting and didnt help, yes it has a mail order tune in it but dont think the injectors flow rate is right, trying to figure that out. I am hoping once it is running right 400+ ponnies. and no I didnt have any issues before the 383 build other then I BLEW it up. LOL I still thing the pump it the bleed down issue

 

ttt

 

if you are holding 42lbs at idle your pump is fine I wouldn't change it out until you look at whether your tune is correct for your injectors and that you have the right type of impedance for your injectors also.. I believe stock are high impedance, if you have low impedance you could be running the wrong injector.. 42 is a lot of injector for you also unless you are going forced induction.. I run 400+rwhp and use 30lb svo's, I would think you could get by with just a tad above that..

I would contact whoever did your tune before wrenching any more.. sounds out of whack, my mailorder was way off on fuel when I did my first major engine mods..also check the boards over at cz28.com and see if there is someone local who knows their stuff.. wish I could help more just try not to fall in the trap of pull and switch, that gets expensive fast.

 

the 42 will be good for my application, just need to get it straighted out. I did drop the tank and there were some issues I fixed. I am working with a friend on one of the other sites

 

Ok, good luck.. share what you find out it doesn't sound like a run of the mill problem to me anymore and what you find is good knowledge for someone else.

 

I will do.