LS1Lust

My Trans Am is having some problems in the upper RPM range, from about 4k-6k.

Here is what it was doing. At WOT above 4k RPM the car would start to chug. It felt like intermittent losses of power. Kind of like I was pulsing the throttle, and this would happen all the way up to 6k.

However last night my friend and I were in the car and decided to get on it to see if could figure out what it was doing. Well I went WOT in first and when it got to about that 4k RPM mark it felt like it just stopped accelerating. The RPMs continued to climb but it felt like there wasn't any power left. The engine also sounded like it was really straining. I did this in first and second gear.

I am thinking this may be a fuel delivery problem but I thought I would post here to see what you guys thought. My car has the mods listed below and is un-tuned. Also it is at 61,xxx miles.

Thanks,
Alex

99DWPTA

iTrader: (10)

any check engine lights?

LS1Lust

nope nothing like that.

BigJls1

my 98 T/A fuel pump finally went out at 62,000. I didnt think it was bad until my wife ran it out of gas and it would not restart. after a walbro 255 install I picked up almost 1/2 a secound in the 1/4 mile, this leads me to belive that the fuel pump proir to this was not giving enough fuel pressure. Is that the factory pump in yours ?

LS1Lust

Yeah it's a factory pump. Will putting a pressure gauge on the fuel rail tell if there is some thing wrong with the pump? Or do I need a gauge in the car so I can see what it is doing at WOT?

BigJls1

IN my opinion yes. My pump held pressure at idle. I cant confirm that there was pressure drop at wot as I did not know it was weak and never thought to put a gauge in the car, the time slip says so though. Just a suggestion here, why not save the money and labor of rigging up a fuel pressure gauge in the car, and just go with the walbro. The walbro 255 kit was aroud $200 and will support many future mods I think it's good for like 600 rwhp.

Thule

mine does this to..

mad power in 1st 2nd and goes lean in the higher gears.. and loos power above 5k rpm

LS1Lust

Well I just ran a fuel pressure gauge on my car and was at 42psi with just priming the pump and then between 54-56 at idle. Which from what I can tell is where it is supposed to be. But is it possible that the pressure doesn't drop untill it is in the higher RPMs?

LS1Lust

Ok new information. I just took it for a drive with the gauge visible. At wide open it droped to 32psi and just stayed there all the way up to 6k. And even under normal driving it would drop about 2-4psi. From searching this seems to be a problem . However I have seen some people talking about the regulators being the problem. Is there any way to check and make sure this isn't the problem before I drop $200 on a new pump? Also I changed the fuel filter after this started happening and it didn't do anything.

LS1Lust

anyone?

LS1Lust

bump!

SovXietday

95% chance it's your fuel pump dude, it can't keep up with the fuel needs at WOT conditions.