Hey guys my 1990 454ss is starting to **** me off. The truck runs like crap at part throttle and stutters an WOT. So far I've replaced the coil twice, dizzy, plugs, wires, knock sensor, and O2. And the problem is still there and seems to be getting worse. Anything else I should look at? I have a pressure gage and adapter on the way so I can check fuel pressure. Truck is all stock with the exception of no cat, and the timing is set at 6 deg btdc.

Thanks
Mark

 

Make sure the timing is what it's supposed to be, otherwise it throws off the timing in every table (unless you are custom tuning your chip).

Otherwise, deffinitely check the fuel pressure.

 

Classic signs of a lean condition. Replace the fuel filter and go from there.

 

Get your FP guage and go from there. It could be a clogged filter or a failing pump.Once you hook your guage up you'll know.

 

Truck only has 7 psi of fuel pressure. Not good huh?? Should be around 13 right? Where should I start the regulator or the pump? The filter is only a few months old.

Thanks
Mark

 

Perform a dead head test - pinch off the return line, while observing fuel pressure. If it zooms past 20 PSI FP is probably OK if it stays around 7 PSI, you have a tired FP, or fuel sock, or clogged in line filter or ruptured in tank hose.

//RF

 

Regulators rarely fail by just loosing pressure. If they fail, which is rare, they rupture the diaphram and leak. Your pump is dead......

 

Not necessarily, I have seen ALOT of springs fail by breaking into two.