Fuel injection questions

[HOOKERBEAR]

I have a 90 GT that I turbo'd as well as put #42 injectors with matching MAF and 255 LPH fuel pump. My question is how much fuel pressure do I need to be running with this setup? It currently runs between 41-44 psi on the rail, do I need to be running more than that? Would it make a big difference if I put an aftermarket fuel pressure regulator on it? Its also running rich and seems to be loading up on idle (there are no vacuum leaks), if there is anything I can do to get it to run better than that short of tuning(chip) I'd love some suggestions. I'm also curious about how others who have put larger than the factory 19 lb injectors on their Mustangs and how they behave.

 

[BlownFiveLiter]

Most tuners are probably going to want you at the factory pressure of ~39 PSI with the vacuum line disconnected. With a turbo and 42's, you really want to get it tuned, or you're going to become a master at replacing head gaskets in no time flat.

 

[prgt347]

With my setup and the factory computer it ran rich also. Running 30# injectors. I took mine over to JMS in Lucedale, MS and they smoothed it all out. I've been very pleased with their tune and the price wasn't bad. I'm sure there are other shops in N.O. but this one isn't too far from you, if you want another to consider. Take I-10 east to Exit 69 (HWY 63 / Pascagoula) and go North and follow it for about 20-30 minutes. JMS is on the left out in the middle of nowhere. Give them a call first, though...

 

[2002BLGT]

Set fuel pressure at 39 with no vacuum on the regulator , hook the vacuum line back up , verify your 0 mark on your balancer with TDC and make sure its not wobbling , set base timing at 10 degrees and then get it to a tuner for a dyno tune.

 

[HOOKERBEAR]

My current fuel pressure with no vacuum hooked up is 41 PSI. my next questions are what are the conditions that cause head gaskets to blow? running too rich, too lean? Since it has 42 lb injectors will that cause the engine to load up and die on idle?

 

[greyfox69]

Not meaning to thread jack but I am new to the mustang family. I just bought an 88 gt and the guy said it had a larger fuel pump but didnt mention injectors. Is it fine to do that without changin out the injectors? also first time trying to crank car over it wont start. if u flip the key back it usually will fire up on second. He claimed that was due to larger fuel pump as well. True??

 

[HOOKERBEAR]

I don't think that the larger fuel pump would make a difference, it may if your injectors are running at a much higher than stock pressure. What all has been done to this car you just bought? Turbo?

 

[greyfox69]

I don't think that the larger fuel pump would make a difference, it may if your injectors are running at a much higher than stock pressure. What all has been done to this car you just bought? Turbo?

only thing to my knowledge that has been done is E303 cam, ugly crappy super cheap intake and a larger fuel pump. Im pretty sure I have a vacuum leak cause i have alot of things that should be plugged into something that arent. look up Noob chick from kentucky thread and there is a vid of it idling.

 

[HOOKERBEAR]

From how it sounds, as well as looks, you have lots of things unplugged that should probably be plugged in. I would get rid of your vacuum leak, and make sure everything is properly connected. Since your car is a speed density car I would consider converting to a MAF, your intake system is also straight crap. You'll lose power with that thing, you'll be sucking in hot air from the engine and lose power that way, I would find a better intake system, that might help. I'd double check timing just for good measure as well.