s-15 pickup wont start

Maybe just flooded? If so, let it set awhile and recharge the battery if necessary. Best technique with a flooded engine is to gently ease the throttle open so as not to get a big squirt from the accelerator pump and crank until the engine starts. It will run rough for several seconds till it clears out the excess fuel.

Other than that, I don't know either.

This is only a guess but based on what you wrote, maybe it's a bad or weak fuel pump. (can be checked with a pressure gauge and it perhaps operates between 50-60 PSI as a guess).

Another possibility is a bad gas filter, clogged or partially-clogged line. I do understand that the fuel pump is in gas tank. Not fun to replace.

Assuming your carb gasket is good. I underastand that can contribute as a possibility.

Further guessing is that it could be a plugged catalytic converter as at this advanced milage it's not out of the realm of possibilities.

dude...

if it has a carburetor, it's running less than 10 lbs of fuel pressure. more like 4 or 5...

I would check and make sure I had spark first.

remove one plug wire from a plug, and insert another good plug. hold it against the manifold, and have someone crank the motor over.

watch for spark.

if you have a good crisp bluish spark, move to step 2.

see what the flow from the fuel pump to the carb looks like.

step 3 puts you back inside the carburetor you were working on.

good luck...

the rebuilt carb had a new gasket so it should be ok . the fuel pump is acualy old enough that it ismounted to the blockk and some typerod connectinng to the crank i guess it only pumps with engine running . i cant imagine it being clogged so abruptly and i am still learning so i would not think to check theconverter or no how . thank you

hey...I brain farted.....doooh,. you're right. not EFI..carb..force of habit.