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Fuel pump not always turning on???

M

millertime

NAXJA Forum User
Location
minesota
Every now and then when i go to start my 91xj the fuel pump doesnt turn on. I will sit there and turn the key on a few times (sometimes 1st try, sometimes 5+) before the fuel pump will finaly turn on. Then once it starts it runs fine?

I did the obvious thing i replaced the fuel pump relay but that didnt fix it, all the other fuses and relays seemed to be working just fine.

I was wondering if any of you have any ideas on what might be causing this to happen?
thanks,
-Jesse
 
Bad fuel pump. Most likely a shorted winding or some such on the motor. if the motor stops in the right place, it will start right up, if it stops in the wrong place, turning the key on and off will move it ever so slightly so it will start.
 
tommyr said:
Bad fuel pump. Most likely a shorted winding or some such on the motor. if the motor stops in the right place, it will start right up, if it stops in the wrong place, turning the key on and off will move it ever so slightly so it will start.
Click to expand...

spose the only fix is a new pump then... thats a bummer.

thanks for the help,
-Jesse
 
millertime said:
Every now and then when i go to start my 91xj the fuel pump doesnt turn on. I will sit there and turn the key on a few times (sometimes 1st try, sometimes 5+) before the fuel pump will finaly turn on. Then once it starts it runs fine?

I did the obvious thing i replaced the fuel pump relay but that didnt fix it, all the other fuses and relays seemed to be working just fine.

I was wondering if any of you have any ideas on what might be causing this to happen?
thanks,
-Jesse
Click to expand...

How many miles and is that the factory pump ? I does sound like the pump is bad. Before replacing check the fuel pressure, it will indicate low even if it is running. And 30 PSI is considered low.

Good luck
 
Would you be so kind as to inform those of us without telepathy what year you might have?
 
I just searched for like an hour on what could be wronge and cant find anything? you guys have any clue?

any help would be awsome,
-Jesse
 
Probably (as stated earlier) a bad fuel pump. but highly unlikely if you changed for a new one.You changed the relay so the resistor block is the only culprit left other than the pump being a new bad pump.

You may have a broken wire leading to the pump as well. Highly unlikely but an outside possibility nonetheless.

Another thing is the ignition switch itself. That could be bad but again a distant possibility.

The resistor block seems the next step among the choices we have IMHO. I have little experience with a 91 HO. My junk is older than yours.
 
Last edited:
I checked the wires from the pump to where they go inside the body and everything on that end is ok. I guess il check the fuse block next to see if there is a bad wire or conection there.

thanks,
-Jesse
 
Well i replaced the balist resistor now too and still not working correctly. I called my dealer and they said it might be the ecu? anybody had that happen?

let me know,
-Jesse
 
Well i traced the wires as much as i could and couldnt find any broken ones. I took the plastic cover off of the relay and it wasnt turning on. as soon as i touched the contacts on the relay the pump would turn on. I though well maby its a bad relay again so i changed it but it did the same thing... So for some reason the relay isnt getting power?
I cant find any broken wires or grounds under the hood so maby it really is the ecu?

anybody have anymore info?
-Jesse
 
Is it possible to hook up a couple wires and a 12v bulb to the harness at the fuel pump so the light would light when the pump had power???
I know you don't want any sparks back there, so the wires would have to be secure, but this way when it craps out, you could tell if there is power back there or not. That could at least rule out the pump being bad.....
After that, maybe move the bulb to where the relay is getting its power seeing as you think maybe it isnt? Tough one.......
 
Sounds like classic shakey ground wire syndrome.....

and.....

are you sure the ballast connections are secure?

Did you try leaving the key in the on position and jiggling every fuel pump related wire untill the pump comes on???


Last resort:try a new ignition switch.....
 
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