Hello all
I was wondering if any techs can help with what SHOULD be an easy question. I received my new OEM fuel pumps today and I want to bench test them before installing as I have no desire to install a bad pump.

They are the two pumps from my 01 XKR. There is a simple two pin connector that is labeled + and -

Can I simply power the pumps off a battery on the work bench and expect the pump to fire up? (did not work) The pumps will not fire up? Neither do my old 'bad' ones??

Do I have to run power to the pumps through the resistor wires from the tank? (that didnt work) Do the pumps have to be submerged to work? Do the metal brackets have to be grounded? What am I missing here??!!

Any advice would be appreciated. prior to removing my fuel tank I had no pressure at the fuel rail, swapped relays and check all fuses, had no noise from fuel pumps in the trunk when powered up, had no noise from fuel pumps when jumping the relays. I hope I did not just pull my tank and pumps and buy new ones for no reason!!!
AGGHH

 

Jed, first off, do NOT!!!! run the pumps with out some sort of fluid inside the pumps. The gasoline is what lubricates the bearings inside the pump. So, as you can imagine running the pump without atleast some fluid in there would be bad.

As for how to make the pumps run, I would need to look at my diagrams (which are at home) as to what it would take to make them run. I would say that you can get a small container with 2 hoses so you can recirc some fluid into/out of a container. That way the pump can move the fluid and you will be able to see the fluid move.

 

Chris,

Thanks, good advice. I can easily rig a hose and bucket setup to push some fluid around however the pump doesnt even try to run when I give it power positive and negative direct from a battery). It does however make the most subtle clicking noise. My old pups dont even do that.

I would just like to know that this (bad fuel pumps) is in fact my problem before I replace these and pump it all back together.

Thanks again!!
Jed

 

If you look in JTIS, there are a number of resistance readings you can take as a test. You must also test the link leads as these are known to fail.

Running the pumps without being submersed will ruin them.

If you really must run them, then submerging them wired into a covered plastic bucket with the leads running out through holes punched in the lid might work to keep sparks separate from vapors.

Once you have the tank out, you may as well replace the pumps no matter what the condition of the old pumps as most of the work is in taking the tank out.

 

Thank you Plums.

I cant seem to find any resistance testing in JTIS??

I guess I need to know how to test the link leads? From what I can tell there are three separate wiring leads. One external to the tank, and two in the tank.

Can anyone describe how to test these links please?
thanks!

 

Jed, when testing the fuel pumps, like you have figured out, there are two pumps. What you need to do is to look at the plug on the pump complex. You should see 6 pins. You need to connect the positive side of your power supply to pins 2 and 6. You need to connect your ground to pins 1 and 5. When you do this, the pumps should come alive.

The pumps are powered directly off of a relay. So, there is no quick pulsing of the fuel pumps or some special digital signal that they are getting. They are running off of straight DC voltage. it is possible that if you were connected up to the wrong pins or may have had the power wired up backwards. either one will cause the motors to not run.

Hope this helps.

 

Thermo,

thank you for the informative reply. I will test the pumps as you described but currently they are totally uninstalled and when I put power to them I went directly to the pumps two pin connector. No wire harness or link lead. Straight from the battery pos and neg to the pumps and the pumps are clearly marked pos and neg so it wasnt backwards. I can understand why the old pumps didnt work but why dont my two new pumps spin when I pulse power to them? Nothing, they do not spin at all. If its a dc connection they should spin shouldnt they? I am totally confused by this. The only thing I can think of is that they need to submerged to be able to spin at all and I suppose I will have to try this.

I can also reconnect it all and test it by the pin configuration you described but then I am testing the pumps AND the wiring harness. I just want to know these pumps work before I put them in and button it all up. Once I know they work I can test the harness as you described.

No way I got two bad pumps sold to me by the jag dealer....i must be missing something??!

 

Jed
I had a mechanic tell me that they cannot be tested dry. they can be destroyed by putting current to them without being submerged. That's a could be a hefty price to pay especially with Jaguars prices.
Good Luck

 

I'll probably get slapped down by many of you, but I don't think momentarily running the pumps dry will damage then at all. Just look what happens when you run out of gas; the pump continues to try to pump fuel as long as the ignition key is on. It's pumping nothing but air, but you don't hear many stories about someone running out of gas and destroying their fuel pumps.

Fuel does not conduct electricity, so unless there is a float switch in the pump (unlikely), the reason they aren't turning on has nothing to do with whether or not they are immersed in a fluid. I'm 99% sure that the pump has to be grounded in order to run. But you can't just ground it to your workbench. In a car, the negative terminal on the battery goes straight to the chassis of the car and the chassis is used as the return path for the electricity to get back to the battery. You probably have to connect the chassis of the fuel pump to the negative terminal on the battery in order to make the pump run.

 

I know this doesn't apply to your situation because of the model year of your car, however, for 2003 and up, the pumps are pulse width modulated, not dc current driven, therefore, anyone with a 2003 and up should not attempt to test the pump by applying voltage from the battery.

 

Actually... I have to disagree again. The pulse width modulation pulses are still 12vdc. The pump will run hooked straight to the battery. I know this because on my car I rigged up a thing to pre-pressurize the fuel system. The check valve in the pump had gone bad and it was allowing fuel to run back into the tank, which resulted in long cranking times. I temporarily fixed the problem by rigging up a contraption that used a relay to automatically apply 12 volts straight to the pump for about 10 seconds before I started the car. It worked, but about once a week I got a check engine light because the pump controller was detecting that the fuel line pressure wasn't matching what it was telling the pump to do.

So even on the newer cars I still think it would be OK to hook 12 volts straight to the pump to see if it spins.

Having said that, I don't know what that is really testing, other than making sure the pump spins. It might turn fine with no load on it but then bog down with 55 psi of fuel in the lines. If I was the OP I'd just slap those fuel pumps into the tank and see what happens. But that's just me.