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fuel pump/gauge

Superflie

NAXJA Forum User
Location
SLC, UT
I have a 1991 XJ 4.0L and I have a question. I've looked through the forums on this and cant find anything. My fuel pump does not pump when i first turn the key on, once i start it, it works great. should it work right away? Also, my fuel gauge doesn't read anything and the light is on. Could this all mean my pump is going out? The only thing i found was talk of the CPS and i've replaced that. Any help would be great. Thanks all
 
the pump wont work untill you turn the ignition all the way to the cranking posistion. it has a safety switched to the oil preasure sensor so in case of a crash or rollover and the engine dies, it wont continue pumping fuel. so basically to test the pump you need to give it its proper voltage. some models will allow a second or two run time when first turning the ingnition on, but basically you need to have it at full cranking position.

as for the guage, were does it read? empty? the float for the in tank sender is mighty close to the fuel pump screen and can get caught up on it if the screen has been twisted slightly during installation or something.
 
yeah, it reading empty right now and the light is on, this started on a super cold day this winter. Before that it had been working fine
 
the sender and the pump are not related inside the tank. They simply share a ground.

If your gauge is not working, it's likely a shoddy ground.
Clean all the connections and connectors, check the harness for damage.
If it still doesn't work, disconnect the connector and stik a DMM set to ohms on the sender wire coming from the tank. Ground the DMM to the chassis. If you don't get a changing reading with different fuel levels in the tank then the sender is bad.
 
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