Short story,
Live in a very rural setting, no close garages nor mechanics, sometimes a bit of knowledge will HELp!

Have a 2003 GMC, Senoma, 4 cyl, PU... Full charge battery, 3/4 tank of gas. Turn om ignition, dash Battery light shows red. Turn key to, start position, Starter strongly turns engine, will not start after many tries, battery red dash light stays on. ?? Advice ?

PM 's are ok

Are you getting spark? Fuel? I know you said it has 3/4 of a tank but is it getting to the motor.

Sure sounds like the thing to do, saying that I guess I'm just losing touch with modern motors, looking at this one. I have absolutely no way in heck to tell how to check either spark or fuel flow into the engine, maybe its just time to say , "I just shouldn't try."

Thanks smile

I don’t think your a dummy..... next time post something like this
In the O/T section you’ll get more help for sure.

Sure you do! Checking for spark is the same as it's always been... pull a plug, put wire back on hold it against the head, crank and see if you get spark in the gap.

Have you ever changed your fuel filter? Probably on the frame rail under the bed. Disconnect the fuel line from the engine side of the filter (might be a nut, might need a special tool to depress/push some locks) and turn the key on and see if you get fuel. That will confirm filter and in-tank pump. On V6 and V8 FI cars, there's something called the fuel rail which is where fuel connects from your supply and then the injectors for each cylinder are connected to this rail. I don't if your 4 cylinder will have it or if you have port injection or a central throttle body. There is a a schrader valve (like a valve stem on your wheel) where if the ignition is on (rail will be pressured up with fuel), if you depress the pin like to let air, out, you should get some fuel spray. That will at least tell you there is fuel at the injectors.

You should pick up an inexpensive code reader as if there's a sensor or something that's gone bad, there will be a code set you can read and tell you more precisely where to go look.

Could be your alternator, could be fuel pump, could be bad computer, could be clogged fuel lines. Get the code reader like mentioned above (they are cheap from Amazon), also google search your symptoms and check out the GMC forums.