Maybe someone here knows the answers to a couple questions a friend of
mine has regarding Chrysler Fuel pumps and his battery.

He has what he thinks is a dead fuel pump in his 94 Voyager.

So he got a used pump and tested it with 12 volts to see it spin up. He
then installed it and it still won't spin up in the tank. He 'thinks'
he heard it spin when he put the key to 'run' once but no start. I am
disabled and can't get under there to check it for him.

I made a couple observations. One, the 'new' pump has 4 wires off the
plug and the old one had 3. The ground for the gauge and the motor
ground appear to be common in the old pump and separate in the new one
so he soldered the two wires together.

The 'old' pump will also spin up when hooked to a battery.

The fuel pump relay looks good with nice clean contacts inside and on
the spades and it clicks when the key is turned. Voltage was observed
at the pump plug. Not enough maybe?

His battery is acting wrong I 'think'. It has a good 24 hours on the
charger to bring it up over 14 volts. 30 seconds with the lights on to
take the surface charge off, then off drops it to 13V. When the key
hits run, it dives to 12.1 or so volts. When the starter turns, it
drops to 10.2V.

I am of the opinion the battery doesn't have enough power to fire it up
maybe.

Could he just plain have the wrong pump in there?

Any suggestions or guesses would be appreciated.

Mike
86/00 CJ7 Laredo, 33x9.5 BFG Muds, 'glass nose to tail in '00
88 Cherokee 235 BFG AT's