This is my first post on this board, as I have just acquired a '98 Blazer with a 4.3 Liter.
When I turn the key I hear no fuel pump coming on. When I pour gas down the throttle body the motor will run until the gas is exhausted.
My first suspect was Fuel Pump Relay, so I opened the relay and fuse control box and changed the fuel pump relay with two or three relays by same number in the box, switching the relays did no good.
Now I am thinking I may have a froze fuel pump as this car sat up for 11 months, but I want to be sure before I go through the skint knuckle process of removing the tank to replace the pump.
Someone told me it was possible to use a jump wire from the positive post of the battery to one of the relay terminal inserts to find out if the pump will run if the relay is bypassed. But I do not know which of the terminals I should send the 12volt current directly to. The terminals are marked 1 - 5, do any of you have any ideal which terminal I can use to send direct current to the pump for a test?
Thank you for any help you can provide.

 

i wouldnt recomend jumping the realy, try this....grab a friend and while you turn the key to the start position, have your friend beat on the bottom of the gas tank directly under the fuel oump / sending unit with a hammer (not to hard as to dent the tank) and see if the fuel pump runs and the truck starts. it it starts that way, it needs a new pump. if not i would drop the tank and test the circut directly at the tank connector. its not that hard to drop the tank.

 

You can swap out the relays with any of the other relays in the box (horn etc). They are all the same. Sounds like it's time for a pump to me.

 

Test the fuel system:
96+ Fuel System Diagnosis

 

I agree that if you switched out the relay, it's probably something with the pump. It could be no power, bad ground, or a faulty pump. Before you drop the tank find the ground strap that bolts to the frame next to the tank. Check if it's not loose or corroded. If you can find out which wire in the harness is the power wire you can check it for voltage. If you have power and a good ground, now it's time to drop the tank and do the deed. Good luck.

 

Or it could be something simple as the wires are disconnected at the tank. but I would start at the tank check what wires you can get to then drop the tank and go from there.

 

Thanks for all the help,it was the fuel pump,I dropped the tank and changed it.
at first only half the cylinders where working when I started it up as the truck set up for a year but after some injector cleaner she came around,
I have another quick question,
I need to order a RT side mirror,and the title of the car says 1998 but the inside door information tag says 97/11,
which date determines the true year of the vehicle ,
thanks for any help you may have,

 

The tag on the door shows the build date. A 1997 November build is definitely a 1998 model year vehicle.

The VIN determines the year of the vehicle. The 10th character to be precise. You can find the letter to year break down in the LMCTruck catalog on pg 11