i have a brand new gas tank + sending unit on my truck, 2 weeks ago the truck wouldnt start, and i couldnt hear the fuel pump kick on, so i got a new fuel pump... still doesnt start... so i baught a new relay for it... and still does not start... i guess my blazer is just dead now?... like idk.. i might be forced to actually drive my bronco considering i cant figure out what the hell is wrong with my blazer...

 

Did you check other systems?

how is the battery?

 

It would help to know more about your truck. year, make, model, engine, etc.

There is anotehr circuit to kill power to the fuel pump, its the oil pressure circuit. Plus there is a jumper wire under the hood over the master brake cylindar, run a wire from the battery to the red wire and the fuel pump should cylce on.

 

My son just ran into a fuel pump problem. He got some help from a "friend" and they "jumped" the relay. I told him to go out and replace the fuse cause I( wasnt going out to look at anything till it was at least back to a simple problem, not a compound one. He didnt believe me. Hey dad, Ive never seen a fuse blow like this is one is!!! I feel this way. I havent either, but having seen thousands of blown fuses, I have become numb to exactly how they LOOK when blown. Good help is hard to find????

Check fuse? Does relay click when key comes on? If it clicks, does pump run for 5 seconds or so, maybe only 3 and then shut off? NOT WHILE CRANKING. Do this without cranking. Just go through the little check list. Did you save the old pump? Did you check it while still in the tank, but not in the car? May be dangerous if you spark near fumes, but if you substitute water for the gas, you should be able to check the old pum in the old tank.

Did you do the obvious thing? Check the new pump? You know YOU ARE NOT SUPPOSED TO: RIGHT? never run the pump DRY. Not the new one; if you want it to work when you get done. I do it though, but only a one second to two second burst.

If the new pump worked before installed and if you took a good solid GROUND from the outside of the NEW tank to the CHASSIS, then all you need is to plug it in right; right? Did you forget the chassis ground?

A terminal is actually located on the top where the whole assembly twists ut of the tank for attaching that ground. Often this terminal will just break off. So the wire disapears also. I clamp a second one to one of the tubes leaving the tank. I normally use the vent line and a small airplane style clamp. Just tighten the terminal on the wire between the clamp and vent line. Cover with grease to stop corrosion. Drill a small hole in convenient chassis location and a good selftapping screw with nutdriver head. Right nutdriver helps. Two grounds are better than one.

If you had all that right, then what was resitance reading directly AT THE TANK between pump positive and ground? Use this reading to check the wire going to the front of the car at the relay. Compare it to ground under the hood and the reading should be almost the same. (digital ohm meter)

Yes if you dont have oil pressure, you may have a problem. Or unit that senses oil pressure may be bad or disconnected. (unplugged)

Let us knowsome more?