Fuel pump test, out of tank?

[Sonny]

Hello all, I have been working on my other SUV the money pit Rodeo. The setup is pretty much the same as the Explorer as far as the fuel pump. I replaced the in tank pump last weekend to solve a bad check valve problem (hard start). It starts fine now except the fuel gauge will not register above a 1/8 tank, and the check gas light goes off/on.

My question is, I have a new pump on the way, can I check that the sending unit is working before I reinstall it, will any damage be done to hook up the electrical and operate the pump and also control the float by hand to confirm the fuel gauge is seeing the pump.

I did check the connections and the fuses.
Thanks for your help.

 

[RiverRat]

Yeah, what I would do is hook up a multi meter up to the fuel sender leads and bench test it. Move the float to full tank and empty and see what resistance readings you get. See if they match specs.

Or if you meant to hook it up to the vehicle wiring and check it that way is ok too. You won't damage the pump if it is only run for a short time.

 

[410Fortune]

short time is right.

Also some pumps will die if you suck air through them.

You should be able to get a reading on the multimeter from the gage sender without powering the pump itself.

Dont forget the fuel pump uses the gas in the tank to cool itself, so if you run it out of the tank for too long it can overheat and die.

Also the fuel lubricates the impeller, so runing it dry can also cause damage.

Let us know what you find! I dont think I know of one aftermarket pump that has been installed that did not mess up the gage, leading me to assume Ford calibrates each pump/float prior to installation.......

 

[DeRocha]

I would Not run the pump at all..(but that is just me). As mentioned by others the pump uses fuel as a coolant and lubricant (would you run your engine without oil for just a short while?)

I replaced my pump/sending unit a few years back and can't recall the exact wiring. Can you remove the hot lead from the pump and just have power to the sending unit? If so then you could do that without running the pump and causing any premature wear...

 

[lonestar]

If the old sending unit worked fine, put the new pump in the old assembly.

 

[Sonny]

Originally posted by 410Fortune

Let us know what you find! I dont think I know of one aftermarket pump that has been installed that did not mess up the gage, leading me to assume Ford calibrates each pump/float prior to installation.......

I have heard that, I did have to replace the pump in my X about 4 months ago. I must have got lucky, the gauge works perfect.
Thanks

 

[Sonny]

Thanks to everybody, some good ideas. I will do the pump again this weekend if it is here. The damn problem with the 98 Isuzu is there are no Haynes or Chilton's out yet. Makes it hard to work on.

Thanks again