Please help! Is my fuel pump bad? What is blowing it?

[AadosX]

I just checked my fuel pump itself and checked the ohms or whatever (omega symbol). In the FSM it says I need "approx .5" but my fuel pump tested at .8 Is .2-.3 a lot?... does this mean my fuel pump is bad?

NOTE: I don't exactly know how to use a multimeter. Here is what I'm doing. I put the switch thing on resistance range of 200(omega symbol), it's the lowest range on my multimeter. The number I get is 0.8. In the crappy book that came with my multimeter it says the resolution (whatever that is) for the 200 range is 0.1(omega symbol). I am guessing that this means I'm getting .8 ohms and that resolution just means to what decimal place it measures or something.

Also, if it is in fact bad, what could cause it to go bad? It could be a coincidence. This fuel pump is used and I just installed it because my old pump went bad (well, I think it did. the car wouldn't start w/the old one and the fuse wasn't blown. i could never hear the pump priming so I replaced it and then the car worked). This pump worked for one day then stopped working. My old pump never blew fuses but this pump blows the fuel pump fuse every time I try to start the car. Coincidence or what? Does the fact that the pump has .8 resistance instead of .5 cause the pump to blow the fuse? That makes absolutely no common sense to me but I'm no expert. It seems like having .8 over .5, so MORE resistance would keep the fuse from blowing. I just cannot figure out why in the world it would work for one day then out of nowhere the resistance gose up .3 (or is it down?) and blows the fuse. Then again, as I'm typing this I don't even know if the .3 matters and maybe the pump is fine... BUT, IF the pump is fine then I have no idea what is blowing my fuse because w/out the pump hooked up the fuse doesn't blow, even if I close the circuit with a multimeter instead of with the fuel pump.

EDIT: Man, this is driving me nuts. When I take the fuel pump out of the equation everything works fine. I can put the multimeter up to the wires that go directly to the pump and I get 12V all day long with no blown fuses when starting the car. I test the pump and it also seems to be fine. But whenever I hook up the fuel pump and start the car, the fuse blows. Now, I know that fuel pump doesn't = multimeter... they're obviously different electrical devices and maybe that's just the reason the fuse isn't blowing? I thought about putting a 12V light in the circuit instead of the multimeter but didn't know if it'd be a good idea. I don't know what would happen anyways, would the fuse blow? would the light bulb blow? I'm no electrician and this is so annoying. I don't see how the fuel pump could possibly cause the fuse to blow, esp. when it seems to check out. I followed every step in the FSM for diagnosis and I'm stuck. Please help!

THANKS!
John

[projectRDM]

How are you testing the pump?

If in fact the fuse is blowing when the pump is in the equation and it's tested good, there's resistance somewhere. Swap the relay out. If that doesn't do it, disconnect the black/pink trigger from the ECU and ground it, what happens? Report back.

[AadosX]

Sweet, the human god of 240's is helping me. Well, I'm testing the fuel pump by putting the red lead from multimeter to the positive terminal that is actually on the fuel pump, and same for black as well. It's what the FSM told me to do.

I will try another relay next, though this one tested ok based upon the FSM stuff. If the pump is getting the 12V of power when it's supposed to, then I thought that meant the relay worked?

Thanks for the help!

[projectRDM]

Test the pump this way:

Using a 12V-18V power tool battery, connect the fuel pump directly to it, + to + and - to - (obviously only touch the insulation, a dead pump will arc). The voltage won't hurt you, but the arc can cause a small burn. The FSM is looking for resistance, but the pump could indeed be bad and just out of range by not powering on at all. Powering it with an external source will tell you for certain. I'm betting the pump is dead, and the new one isn't any better since it's used and been out of tank, laying out collecting dust and contaminants. Just don't run it for too long without being immersed, the fuel actually cools the pump casing as well.

[AadosX]

Ok, well, when I do that, since it's out of the tank how will I know exaclty if it works? Or do I need to put it back in the tank. Will it just squirt out a little fuel or what? Oh and can I just use a car battery or is that a bad idea?.. I don't have any cordless drills or anything like that. >.<

The newer pump I have is out of a wrecked S14 that was sitting in a junk yard, and was still in the tank and whatnot, so I figured it'd be fine but who knows.

[AadosX]

Ok I just got a new relay and put it in and the same thing still happens. In doing this though, I noticed something else that I didn't know. Before I noticed that there was a ground wire in the harness for the pump, but all it actually did was go to the pumps holder/cage thing. I wondered what that was for and still don't really know. Well, when I put the new relay in and tried to test it out, nothing happened. My pump at the time wasn't actually in the fuel it was just all sitting in my trunk area. So I thought maybe it had to be screwed into the fuel tank for some sort of grounding thing. Sure enough, once screwed in, it blew the fuse again w/the NEW relay... so that rules that out.

What I'm wondering is maybe is the cage or whatever all messed up? I don't see how that's possible. When I was actually testing the wires that go DIRECTLY to the pump itself, obviously the pump and cage weren't screwed into the fuel tank considering that would be impossible. When I did that, I did in fact get 12V from the wires and no blown fuse. See what I'm saying? But, now that the cage is screwed back into the tank, the fuse is blowing again. Is there a short on that cage structure you think?... is that even possible?

[projectRDM]

The pump should have it's own ground. Powering it with a battery will turn the pump on, it will hum like any electric pump will.

The fact that the fuse blows when the bracket touches metal says that the +12V lead is grounding out, either on the bracket or the tank, possibly through the pump itself.