97 jimmy Starting problems

Just took the wires off the gas tank and with the key in the ON position there s NO juice to the switch. Thought maybe a relay so looked at the three on the firewall but there is also three behind the glove box.....hummmmmm which ones are the correct ones. Also changed the fuel filter BUT SILL NO START any and all ideas will be appreciated.

The grey wire at the fuel pump module connector should have battery voltage for 2 to 3 seconds when the ignition switch is initially turned to the RUN position. After the 2 to 3 second "pump prime", voltage should drop to zero. The grey wire should have battery voltage continuously when the ignition switch is in the START position.

OK so tomorrow I am going to put the Blazer on stands and drop the spare to get at the sending unit wires. I know that one of the wires needs to have current when the key is on. From what you posted it's the grey one right? If I have NO power to the pump should I look at the relays?? I believe there is one behind a panel in the glove box. Is there also one on the fire wall? Thanks for replies.....car is driving me nuts. Probably something simple that I am overlooking..........................

See post #2 and post your results.

took the fuel filter off and NO fuel comming from tank. No 3-5 sec pump on, so it appears that the pump is gonner. Going to replace the pump and hsng tomorrow or Saturday. Will advise what the outcome is

Can you hear the pump run during pump prime?

At the module electrical connector:
1) Do you show battery voltage on the grey wire during pump prime?
2) Is the resistance on the black wire to ground less than 5 ohms?
If the answer to both is "yes", the pump is faulty.

Can you hear the pump run on pump prime?

At the module electrical connector:
1) Do you show battery voltage on the grey wire during pump prime?
2) Is the resistance on the black wire to ground less than 5 ohms?

pump prime can be heard once in a while and car will start and run,but poorly. when I shut the car off and try to restart the pump prime cannot be heard. there is voltage to the pump, but no noise. This is a sometime noise/no noise situation. I hasd simular problems with a Rodeo pump before and the pum use to work when it liked to.

Make sure the ground is good, if it's OK, the pump needs replacement.

Dropped the tank removed the old module and replaced the entire unit. Pu it all back together(Pain in the @$$) and truck started right up. Feeling good. Finally got it going and can actually drive the damn thing.

Good! Thanks for posting back with the "fix".