95/vortech fuel pressure

[Leeroy697]

Hey guys last year I put in a 255 pump and now the car is running very rich. I bought a rail mounted gauge to check pressure and its at 67lbs. I know thats WAY too high and was just wondering where most of you supercharged guys are at. I bought an adjustable regulator and i want to back off the pressure but I dont know about where to stop.

 

[FlyBy763]

what size injectors?

 

[Leeroy697]

19lbs. Sorry forget to mention that.

 

[cbarr300]

39 with vac. off

the fpr will up the psi based on boost 1:1 ratio



also, none of this really matters right this second. I'd be more worried about getting some 42s on there. Whoever tuned the car most likely upped the fuel pressure to compensate for size......I bet those 19s are well past their duty cycles which is dangerous with boost.

good luck

 

[SeventyMach1]

Definitely need to invest in some better injectors!

 

[Leeroy697]

I am going bigger on the injectors this winter. I know that Lidio uped the duty cycle but I was thinking that even with the bigger pump that they would still only let in so much fuel but the thing is rich as hell. I am thinking about puting a stock pump back in until the winter when I do the injectors but I just need to find one.

 

[blink327]

I am confused though, even though he has a 255 pump, shouldn't all the unused fuel just be sent to the tank? Basically i thought the pump could never be to big because the computer is going to tell the injectors to spray only so much fuel.

 

[Stanger007]

The computer knows how long to open the injectors to get X amount of fuel through at 39psi. When the pressure is increased, more fuel will get through in the same amount of time.

Sorta like if you have your finger over the end of a garden hose. Let your finger off the hose when there isn't much pressure and a little water gets out. Turn the water on even more and when you let your finger off a LOT more water will come out in the same amount of time.

Wes

 

[Leeroy697]

I am confused though, even though he has a 255 pump, shouldn't all the unused fuel just be sent to the tank? Basically i thought the pump could never be to big because the computer is going to tell the injectors to spray only so much fuel.

Thats exactly what I was thinking and why I didnt think twice to put in the 255. I guess Ill just put a stocker back in to get me through the summer till I up the injectors and maf. I do not want to spend the money to get it tuned just for a stupid fuel pump.

 

[cbarr300]

I wouldn't think the pump is your problem.

try this:

disconnect your battery and reset your KAM. The computer will then relearn a lot of stuff and it may correct your problem.

if that doesn't work:

take your vac. line off your regulator and change it back to 39psi. Then put your vac line back on and see if you're running rich.

NOTE:::::: DO NOT GET ON IT WITH THE LOWERED FUEL PRESSURE!!!!!!!!!!!!

 

[Leeroy697]

KAM??? I am drawing a blank. I can try putting the pressure down and see what happens. Ill just have to drive it around a little bit to see how it reacts. Whats funny about the pressure now is that it does not drop when the vacume line is off the regulator. I thought that was odd too.

 

[cbarr300]

Keep Alive Memory reset. I'm sure you've heard of it before, prolly just a different name.

just disconnect the battery, press the brake lights, and reconnect the battery. Who knows, that may help fix your problem (though I don't know how long it'd fix it)

 

[go-stang5.0]

fuel pressure should increase when the vac. line is off. WHen you go WOT engine vac dissapears and obviously you need more fuel so the reg. will increase fuel pressure to prevent a lean condition.

I bet your fuel pressure is so high that even with the vac. line unhooked your reg. is having a hard time increasing fuel pressure any further.

 

[cbarr300]

that's what I was originally thinking as well...that's really on the highside

 

[Leeroy697]

So you guys think im better off just replacing the pump back to stock? I dont want to have it tuned and I dont think the regulator will help enough. Its not a big deal as there is no gas in it and ive done in a few times before. I just need to find someone who has a stock pump lying around for cheap.

 

[FlyBy763]

So you guys think im better off just replacing the pump back to stock? I dont want to have it tuned and I dont think the regulator will help enough. Its not a big deal as there is no gas in it and ive done in a few times before. I just need to find someone who has a stock pump lying around for cheap.

I dont think going back to a stock pump is going to help you much...Youll be lean as hell if you run a stock pump and stock injectors with no FMU...

That being said, I still have my old stock fuel pump if you want it...

 

[cbarr300]

stock pump won't help.

it doesn't matter how big of a pump you have...as long as the psi is the same you're good. The regulator controls PSI and the pump just supplies the fuel to maintain that set PSI.

ex. If I had a stock pump running at 39 psi (vac off)...and I wanted to upgrade to a bigger pump (maybe an aeromotive A-1000 or a 255), it would STILL run at 39 psi. The only difference is that if your combo demands more fuel, it has the ability to supply it where as the stock pump would be all outta steam and you'd be running lean...which isn't good with a blown combo at all.

I would definitely NOT recommend running a stock pump with that set-up....19s are already pushing it.

Here's another thought. Maybe running that high of a fuel pressure caused the injectors to fail and now they're dumping a lot of fuel. Injectors are designed to work around a certain PSI...and I think that 67psi is pushing it...if not wayyy past it.

if you know a buddy with 19lb injectors, maybe you could try switching them out and see if that fixes the issue.

you said that it started doing this recently, right? Does it run rough at all?

 

[final5-0]

I just skimmed over all the above

I did see 67 lbs

Seems like you'd have to have a fmu to obtain pressure that high

Grady

 

[Leeroy697]

Yes I have an FMU. I had a problem with the car last year with it dieing on me. Thought it was the pump so I replaced it with a 255(why put in another stocker). Turned out the problem was a bad wire on the alarm grounding out. The car was not rich and was running great last year up until I put the pump in. The car has been tuned with the stock fuel system for 3+ years. Lidio at Alternative did all the work so I know it was done right. All this points to the pump in my eyes just because I was not blowing smoke and fowling plugs till I doubled the fuel pump. I wanted to try an adjustable fuel regulator before I was forced to drop the tank. I never had a fuel gauge on the car before so I do not know what to set the pressure at which is why I wanted to know what some of you run.

 

[final5-0]

It would seem to me the more powerful pump would change things.

I really don't like fmu's

They work ... but ... I just don't like seeing all that pressure

You don't have a way to confirm af ratio ... do you

I was kinda thinking about turning in or out the screw 1/4 of a turn
and
Seeing if it got better

but

That is kinda micky mouse if you ask me

Grady