Multimeter woes

[e30onBBSs]

I'm trying to test the amps my fuel pump is drawing, and when I jumped the pump my friend was holding the leads and wasn't getting a reading. I also had a pressure gauge connected to the pump outlet and it got a reading so I know the pump got power during that test. I was like well lets test the battery even tho I knew it had charge. Go to the battery and can't get a reading, and the fuse is good. Is there something else to check on the multimeter?

And when I jumper it I got 10psi and NO fuel. Bentely says 4.3~ psi is where it should be. It this an indication of a bad pump by itself? 1989 325i m20. I assume there should be fuel in the vaccum line connected to the gauge when I remove it right?

[AndrewBird]

How did you hook the meter up? To measure amps it needs to be connected in series with the pump.

I'm assuming you are have a no start issue and are thinking it is a bad pump?

[e30onBBSs]

How did you hook the meter up? To measure amps it needs to be connected in series with the pump.

I'm assuming you are have a no start issue and are thinking it is a bad pump?

I think I did it right but correct me if I'm wrong. I got 2 small lengths of decent thickness copper wire, and "tied" them around the male ends on the pump. Then we put those two copper wires in the female ends. Didn't get a reading and also it wouldn't work on the battery when I switched it to 12V. Leads are where they've always been doing tests for the battery

[Todd Black 88]

Take the connector off the pump. Jump one pin from the connector to the pump like it would be if it were plugged in. Put one of your leads from your meter into the other pin of the connector and the other lead onto the other pump pin. It should look like your meter is a piece of wire in the circuit.

Your meter MUST be able to do DC amps, and it must be a meter that can handle the load of the pump.

Unless you have a DC ammeter. Then you just open the jaws around one of the wires to the pump, making sure its somewhat centered, and bobs your uncle.

[george graves]

Sounds like you hooked it up wrong and blew the fuse in your meter. To measure amps, you must INTERRUPT the circuit, inserting the multimeter INTO the circuit. Not measure across it.

[vpilarrt]

Operating pressure should be 43 psi (3 bar = 3x14.7), not 4.3.

[e30onBBSs]

Take the connector off the pump. Jump one pin from the connector to the pump like it would be if it were plugged in. Put one of your leads from your meter into the other pin of the connector and the other lead onto the other pump pin. It should look like your meter is a piece of wire in the circuit.

Your meter MUST be able to do DC amps, and it must be a meter that can handle the load of the pump.

Unless you have a DC ammeter. Then you just open the jaws around one of the wires to the pump, making sure its somewhat centered, and bobs your uncle.

Thanks for the help! So do I need three leads then? 2 into the female plugs then one to the male end or ends? Would I put the meter across both male ends or just one?

The amps section has 3 settings and the bentely says it should be 7-8 and the third option is 20 so my meter should be able to handle it hopefully, if it will work.

Sounds like you hooked it up wrong and blew the fuse in your meter. To measure amps, you must INTERRUPT the circuit, inserting the multimeter INTO the circuit. Not measure across it.

I checked the fuse first thing and it seems fine but it could be. Only real explanation of why it just stopped working, it turns on and everything. Thanks for the video I learned a lot!

Operating pressure should be 43 psi (3 bar = 3x14.7), not 4.3.

I hope my gauge has bar on it too or else I need something else

Also, should there be fuel in the line when I jump the relay? There was none and it seems like if there is no fuel in the line, directly from the pump, it's not working?

[e30onBBSs]

My gauge only goes to 10 psi. Got one from advanced auto, didn't fit. Need to return that. Then I got the cheap one from HF and it only goes to 10 psi. Where do I get a gauge that goes to 100 and fits?!

[vpilarrt]

Almost any gauge is going to have some generic size fitting. You'll have to get an adapter to fit if to the 8mm (~5/16") fuel line.

Also, an image on how to hook up your multi-meter:

[e30onBBSs]

so I need to connect a wire between lets say the left male and female side, then put my leads on both the other ones?

[Todd Black 88]

Here is a drawing my 9 year old just made for you.

[e30onBBSs]

Thanks for the drawing kid! +1 =)