This problem just started about a week ago, it was running fine before that. It's a 99 WS6 w/ H/C and about everything else. The car will start and idle ok, but when I try to give it any throttle it just hits a "wall" and runs horribly or dies. The more throttle I give it the worse it is. I really don't know where to check, I replaced the fuel filter because it needed it anyway and thought it'd be an easy fix if that was it. could it be a fueling issue?? It has a walbro 255LPh in tank pump with about 10,000 mi on it. could it be something inside the motor? Any help on where I can start to diagnose this would be great, thanks.

 

sound like a fuel problem still. did you replace the sump screen with the pump? could be a tps sensor or something

 

Need to hook up a fuel pressure gauge and see what your pressure is. Minimum you need around 45-55 psi.

 

Also, check the EGR valve and emissions stuff. I would bet on that because it's just when you give it gas.

 

No emissions stuff on the car, longtubes with ORY and no EGR. I'll try the fuel pressure guage, thanks guys

 

if you beated the **** ot the cams for a while (constantly) may be the valvesprings have overheated and lost its temper, and with minimum rpm rise the valve floats

 

when u floor it does it go away and get up and go? i had the SAME problem as you and it was the o2 sensor.

 

well I checked the fuel pressure just now, it was 20 psi at idle and would pretty much hold there or a little under. the car won't rev at all just won't run past idle. Sound like the fuel pump?? any other ideas? Thanks

 

Like I said you need a MINIMUM of 45 lbs, time for a fuel pump....and change the filter or you will fry the new one.........

 

maybe you run the car with very little fuel-no fuel in the tank and fried the pump, I did that with a brand new camaro 98` with actual 660Km total. (I did run our of gas)
SCREAMED AND KICKED everything in the dealer, threatened for a legal refund.... got fixed inmediatelly even they worked untill midnight!!!!!! ;-)



buy TWO fuel pumps, put them in a "T" run them in paralel this is because the OEM fuel pump is marginal at high rpms
this idea is from one of "the books"