[blak stallion7]

At wide open throttle, the car just doesn't have any power. It runs fine up until full throttle. Should I check the fuel pump? How can I check the fuel pressure at WOT? What else could it be?

I have a minor exhaust leak that I am pretty sure is between the header and the block. I don't know if that would have anything to do with this.

Thanks

 

[UntamedMustang]

I'm having a similar issue. Mine just doesn't seem to have any more power after 4000rpm. Sometimes it even kinda boggs down. My fuel pressure at idle is about 28psi. When I disconnect the vacuum hose to the pressure sensor, the pressure only climbs to 30. When it's connect the pressure needle kind of vibrates at 28psi.when it's disconnected and plugged it holds really steady at 30.

 

[UntamedMustang]

P. S. Everything seems fine with WOT until I get to about 4000rpm. I'm thinking mine is more a volume issue. Any help would be awesome.

 

[Iyzik]

At wide open throttle, the car just doesn't have any power. It runs fine up until full throttle. Should I check the fuel pump? How can I check the fuel pressure at WOT? What else could it be?

I have a minor exhaust leak that I am pretty sure is between the header and the block. I don't know if that would have anything to do with this.

Thanks

That could be a bad MAF sensor, try using some MAF cleaner. You could also try unplugging it and driving around the block (try WOT) and see what it does.
As for checking fuel pressure I believe since you have a 99' you should be able to connect a laptop or even a phone to your OBDII port under the dash. You can get a bluetooth adapter or wifi or usb for about $25 and it may be able to tell you your fuel pressure. Don't quote me on that though, I'm not sure if your computer reads that parameter or not, someone else will have to chime in.

 

[stevew01]

Engine running fuel pressure is supposed to be 30-50 psi. Key on engine off it should be 25-40 psi. I would double check fuel pressure first, if it is out of spec then I would change the pump.