Hello,
We have a 1998 GMC pickup full size extended cab 5.0 liters 4x4 and it wont start. It turns over but wont start. We have tryed putting gas line antifreeze in the tank and fresh gas and just recently had a oil change and tune up. Its got a new distrib cap and wires as well as plugs. When driving it a week ago it was raining and I started it up after driving to store and it acted like it was getting enough gas. We can hear the fuel pump start up when you turn the key, we have charged the battery, the lights and radio work when the key is turned. Please help.

Thanks
Wayne and Heidi

 

Test your fuel pressure. Just because you hear the pump turn on, doesn't mean it's supplying enough fuel. Also, have you changed your fuel filter lately?

Could be a few other things:

Blocked/clogged cat (exhaust)

PCV valve

throttle position sensor

Check your vacuum hoses as well.

 

did you check for spark
Im having problems with my 85 gmc and it is a coil problem
never know...you might be having same type of problem