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fuel pump is the suck!

moparman96

NAXJA Forum User
Location
anderson indiana
I have recently replaced my fuel pump, and it is not fried again. the first time I had fried my starter relay, while doing so it cook the fuel pump. Paid to get it replaced because I was on the road and nowhere near home. Now only 2 weeks later it is dead again. Dont know what is going on. I have an idea it might be sending to much voltage to it and cooking it, but I dont know for sure. Im going to check the voltage going to it tomorrow. My question is what is the exact voltage supposed to be? And if I am getting to much voltage back to the pump what would cause it.

thanks travis
 
the pump will run safely at a voltage much higher than should be possible, unless your alternator is putting out far too much voltage, but you would have other problems than just a fuel pump.

Put a meter on it and while cranking you should see straight battery voltage to the pump.

How did you test the previous pump before replacement?

I'm not seeing how a failed starter relay causes fuel pump failure.
 
yeah... this doesn't really make sense to me.

My only thought is that it happened to crap out at the same time, and the replacement pump was defective and died fast.
 
I have to make this fast on my way to work lol. the sock was used. when the starter relay went it got stuck open and it melted 3 wires, so i repaired the wires and replaced the relay. try to start crank but no start. ok wtf, check a few things no fuel pressure. I had just put that pump in like 2 weeks ago. so we put another in and we found that the positive wire going to the pump that is INSIDE THE TANK NOT OUTSIDE THE TANK was all bubbled up, weird. But like i said before was away from home had no tools so i ad to let them do it he put in new pump and strainer but didnt fix wire. we ran a volt meter on wire checks out ok. get back on the road truck drive fine. now 2 weeks later pump dies again. thats my story lol. I dont think it makes any sense either but something is killing these pumps. Its ghosts it tell ya :gee: please help have to get my jeep running good again its my only way to et to work right now.

thanks travis
 
Run two wires straight from the battery to the pump to insure the problem is the pump. If the pump doesn't run then, remove it from the tank and again connect it direct to the battery to test whether it's the wiring external to the pump, or really is a bad pump. They're pretty hardy units, and expensive, so I wouldn't assume they are bad without testing them independent of the Jeep's electrical system.
AND, don't run the pump more than a couple of seconds when testing out of the tank; don't want to burn it up!
 
I had a similar problem with my ZJ. I think, unknown to me, the prior owner had installed a kill switch through the floor. Before he sold the Jeep to me he removed the switch and did a crap job reconnecting the wires with non-soldered connectors. Of course corrosion took over and I lost power to the pump. I only discovered this on my own after a mechanic replaced the pump.
 
I have to make this fast on my way to work lol. the sock was used. when the starter relay went it got stuck open and it melted 3 wires, so i repaired the wires and replaced the relay. try to start crank but no start. ok wtf, check a few things no fuel pressure. I had just put that pump in like 2 weeks ago. so we put another in and we found that the positive wire going to the pump that is INSIDE THE TANK NOT OUTSIDE THE TANK was all bubbled up, weird. But like i said before was away from home had no tools so i ad to let them do it he put in new pump and strainer but didnt fix wire. we ran a volt meter on wire checks out ok. get back on the road truck drive fine. now 2 weeks later pump dies again. thats my story lol. I dont think it makes any sense either but something is killing these pumps. Its ghosts it tell ya :gee: please help have to get my jeep running good again its my only way to et to work right now.

thanks travis

that starter relay did not cause the wire damage in the tank. In order to bubble up the insulation you had
not enough voltage, causing current draw to increase
a pump that was going bad and it's current draw increased.
a severe voltage drop in the harness causing current draw to increase.

I'd start with checking for 12V at the pump harness and go from there.
 
not enough voltage, causing current draw to increase
a pump that was going bad and it's current draw increased.
a severe voltage drop in the harness causing current draw to increase.

I'd start with checking for 12V at the pump harness and go from there.
All makes sense except the first one. With a resistive load (pump is close enough) not enough voltage = even less current draw. A severe voltage drop in the harness also doesn't cause the current draw to increase, it causes the power to be dissipated in the wire, melting the insulation, instead of doing work at the pump.

</nitpick>
 
All makes sense except the first one. With a resistive load (pump is close enough) not enough voltage = even less current draw. A severe voltage drop in the harness also doesn't cause the current draw to increase, it causes the power to be dissipated in the wire, melting the insulation, instead of doing work at the pump.

</nitpick>

true, very true. I phrased it badly.

regardless, the starter relay did not cause the wires in the tank to overheat badly enough to melt the insulation.

Of course it's also possible that the insulation was damaged from 20 years of being in a gs tank. It's hard to know without some pictures.

anyway, I think that the OP has other issues than the fuel pump, and that the other issues are the root cause of the fuel pump malfunction.

WHat year is the XJ? Motor?
if it's a Renix I'd take a close look at the fusible links, it's possible one is bad, and moving it around replacing the starter relay made it work, until you hit a bump.
 
Well I have a 1990 with a 4.0 inline 6. The whole sending unit was brand new from the factory, I replaced it the first tim due to my return line being broken off causing a gas leak. But it was and still is an airtex pump and sending unit. I gather from what ive just read that all airtex pumps are junk and die quickly? If this is the case then where can i get a good pump and sending unit. I did check the power to the pump and its is getting power. So it is the pump so at this point im just gonna replace the whole thing again. The other thing is where can i get a good pump that will work for me and I wont have to replace every 2 weeks.

travis
 
Well I have a 1990 with a 4.0 inline 6. The whole sending unit was brand new from the factory, I replaced it the first tim due to my return line being broken off causing a gas leak. But it was and still is an airtex pump and sending unit. I gather from what ive just read that all airtex pumps are junk and die quickly? If this is the case then where can i get a good pump and sending unit. I did check the power to the pump and its is getting power. So it is the pump so at this point im just gonna replace the whole thing again. The other thing is where can i get a good pump that will work for me and I wont have to replace every 2 weeks.

travis

I had an airtex pump in an Aspire that went 15K miles before I sold the car, It's still going.

Pull test your fusible links.

When does it get 12V? Does your 90 have a white resitor on the fender? If so, bypass it with some suitable wire.

There are crucial crimps under the coolant tank, does the harness look alright in that area or is it nasty?
Checked the grounds in the cargo area?
 
hello i am not try to steal this thread but i have a 89 4.0 xj i recently put in a pump and tank out of a 97. it ran good for a abt 3 months. until one day when i was driving down the highway it would stall out and then start back up. the next day it would start then die after a min of running what do u think it could be.
 
well i went out to my jeep and found that my resistor had a small crack in it. so i bypassed it and it ran fine. but here's the catch i cant find the part at the out parts stores around me
 
well i went out to my jeep and found that my resistor had a small crack in it. so i bypassed it and it ran fine. but here's the catch i cant find the part at the out parts stores around me

the ballast resistor is not needed. Ditch it completely,the pump will thank you for full voltage.

It was put in to alleviate customer complaints about pump noise in the back of the passenger cabin, it was never part of the original design.
 
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