97 suburban fuel pump

[jomcgruer]

I have a 97 gmc suburban 454 vortex, 7.4 ltr engine, I was told that the fuel pump needed to be replaced. We had a problem with our truck idle. It wouldn't go over 10 mph, rough idling, & not getting fuel to the engine. I took it into a mechanic that did a fuel pressure test, scan, maf sensor inspection, etc. They said that we needed a new fuel pump. We replaced the fuel pump, strainer, & fuel filter. Now it won't start at all. Help!!

[old_master]

The fuel pump should be activated for 2 to 3 seconds when the ignition is turned to the RUN position, can you hear it? If the pump is being activated, check fuel pressure at the fuel rail and post the pressure here.

Do you have a good blue spark at each spark plug while cranking, (ignition in START position)?

[brcidd]

I have seen 3 scenarios like yours in my life- all were on 454 engines- where the oil pressure sensor/fuel pump switch terminals arc and melt- interrupting the fuel pump circuit- and not allowing enough voltage to the fuel pump- engine bucks, stumbles- dies etc-- Since you quoted a 454 engine-- I would check the oil pressure sending unit--those engines run extremely hot and can melt plastic-- Heck I even melted the rotor on my distributer once--on my 454 Dually- after pulling my gooseneck on a 95 degree day.....

[rhandwor]

I would check the voltage at the pump and the ground connection. If these are good a pressure regulator maybe bad check the pressure at the filter or preferrably at the test connection if you have an adapter. You can use a clamp and pinch off the return hose if it starts good a new pressure regulator is needed.