Will not start but if i put alittle gas in carbator it will start till fuel is gone. fule pump? fuse? relay?how do i check? 1994 gmc 2500 350 motor

ck your impact switch, reset if needed, it its good, fuse or relay, if power is getting to pump the pump may need replaced

Maybe pressure regulator

Try spraying carb. cleaner in throttle body while turning the key. If this works, most likely have a bad fuel pump. Good Luck

Did you check for fuel pressure on the line from the tank while you had the filter off? Do you hear your fuel pump prime when you turn the ignition on? First I would listen for the hum of the fuel pump when you turn the key to the run position (not starting the engine) May have to get a helper and listen at the gas filler neck with the cap off. If you dont hear your fuel pump, check your fuses and relays. If the relay clicks when your helper turns the key on ( put your finger on the relay and ear down close to feel/hear the relay actuate)., and fuse is good, yet you do not hear the pump prime, I would say your fuel pump is shot.

If it is a diesel,check for fuel pressure coming off the direct drive pump hose while cranking the motor.

Mike

You can check to see if the fuel pump is bad..Remove gas cap and listen into tank while another person turns key on.If you here a buzzing noise the fuel pump is most likely OK...If you don't here anything Check owners manual for fuse location and check to see if there are any blown..There is also a fuel relay fuse under the hood

It sounds like an air lock or a fuel pump issue. firstly get the filter changed and bled through this might help. if the problem persists check the pump.

Regards

Dan

check fuel pump relays. there should be a reset button and or switch. mine was located behind my glove compartment. check your manual for location. also check fuses for fuel pump fuses.

Replace fuel pump is the answer given by those who don't really know anything or just want to sell pumps. Too many peole just replace there pumps only to find it doesn't solve the problem. You have to diagnose the problem. This could be bad fual pump relay, open in fuel pump circuit, ground problem in fuel pump circuit. Check voltage at connector near fual tank. low voltage here indicates a possible wire or relay problem. Check resistance to chassis ground from ground pin at connector supplying ground to pump. Any resitance over .3 ohms indicates a ground problem. Check resistance across the pump motor, infinite (open) resitance indicates a bad pump. normal pump resistance is usually in the range of 2 to 4 ohms or so (Check manufacturers specs to get your pump motors resistance). If you do pull pump, check operation by putting 12 volts (correct polarity) across the original pump before buying replacement. If you hear (or feel) pump run, problem may be somewhere else (not pump). With a little well thought out diagnistics, you should be able to quickly pinpoint the real problem, even when it just looks like a fule pump problem.

fuel pump relay is under the hood in the fuse/relay box. information is in your owners manual.
when was the last time you replaced the fuel filter, maybe its plugged?

hi ted , the grey wire at the fuel pump goes to the fuel pump relay , and the relay gets its power from the ECM B fuse 20 amps , located in the underhood fuse relay center , when you tested for power , how did you do the test ? a test light at the grey wire while someone was cranking the motor ? i'm looking for a fix ya vote , so if finding your fuse doesn't solve your problem comment back before voting and i will help you , thanks .