I have a 95 gmc jimmy with a 4.3 L votrtec engine and it won't start unless I put fuel in the throttle body and it'll start but won't stay on

is the fuel filter blocked possibly?.. also those have problems with the furl pressure requlator on those ..

I'm following another issue like this on a 1996 Jimmy.
This engine requires 60psi or more fuel pressure to run.
You need to have someone check the fuel pressure at the rail- throttle body with a gauge.

Fuel injected or throttle body injection? Make sure its getting fuel delivered all the way to the intake.

Fuel Pump or starter. Since you say it's turning over but won't start I'd say it's your fuel pump. You'll probably have to drop your gas tank to fix this problem as your fuel pump is in the tank. You might be able to just loosen the straps and lower your tank a little to access it without removing the whole tank. Check around to local junk yards for this part and you'll probably find it for half the price as new. Make sure you can get your money back if the used pump doesn't work before you pay for it though. Don't forget to run fuel system cleaner (2 bottles to a full tank) once a month.

This happened to me I had to spray Starting fluid everytime eventually. Starting fluid wouldn't work after awhile. Its the fuel pump. Even though it comes on and works its not producing enough fuel pressure to start the engine. It's probably giving about 12-13lbs of pressure but it needs atleast 14lbs. of pressure. And a word of advice to buy a ACDelco original fuel pump if you don't want to have to replace it again in 1-2 years, it's more expensive but will last.

Check fuel pressure regulator.Start engine hook fuel gauge to fuel line check pressure ready then pull the vacuum hose of the fuel regulator if pressure rises 5-10 psi then its good.

throttle body(carb) is bad

Clean the Idle air control valve (IAC), it's located by the throttle body so the best thing to do is give the throttle body a good cleaning with throttle body cleaner. Do not use carb cleaner, it's to corrosive for the gaskets used on the throttle body's. Just follow the instruction on the spray can and after your done putting everything back together. Turn the ignition key's to the run position for 10 seconds and then off for 10 seconds to reset the IAC. Start the engine and let idle for 1 min and go for a test drive. If that does not work, turn the ignition to the run position and pull the ecm(BATT) fuse out for 30 seconds and then place it back in start te engine. The engine may stall but let it, don't touch anything. Just start it again and let idle for 1 min then go for a test drive. The ECM is just relearning the sensors like the first time the jimmy was driven off the assembly line. Good luck and hope this helps. Keep me posted be glad to get your jimmy running 100%. 

It sounds like you need a tune up, Spark plugs and wire and cap and rotor, fuel filter and clean the EGR Valve. I'ld say the EGR valve is dirty with carbon which is common in the 95 JIMMY"S and BLAZER"S which also means the throttle body needs to be sprayed down with throttle body cleaner, not carb cleaner since it's to corrosive to the gasket on the throttle body. Keep me posted, be glad to answer any questions you may have and good luck friend. 

I change the fuel pressure regulator and fuel pump relay, now runs better.