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Old 06-08-2008, 02:39 PM
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Kia fuel pump, again!

I had a problem with a neighbor's Kia burning up the fuel pump wires a few months ago and we solved that problem by replacing the grounding wires. It has been running OK until now but now the fuel pump will not run. I checked the pump and it runs fine with power applied but before doing that I have determined that neither the main nor the fuel pump relay will work. I got a wiring print, a sketchy one, and determined which pins on the computer ground the relays and sure enough if I disconnect the computer connector and ground those pins the relays kick in and the fuel pump will run. I have checked this thing throughly for bad ground connections and even went so far as to add grounding cables from the battery to the frame and engine to the frame but nothing so far has made any difference. OK, as a last resort after checking everything I could think of to check, wiring, grounds and the relays he bought a $400 computer and still nothing! We know that everything is OK from the computer connector all the way back to the fuel pump and the problem is definitely with the computer not grounding the relays, but why not?

One other thing happened when he first brought it over, the main relay beside the fuel pump relay did work at that time but after disconnecting the battery to clean the terminals and check the battery to engine ground wire it has never worked again but nothing else was done except to clean these connections. Any ideas on this mess?

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Old 06-08-2008, 04:45 PM
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If the wiring up to the computer is good and the computer is good, the only thing I can see is the connection of the wiring to the computer.

And maybe you should change that main relay. I've had many strange things happen when I did something and then something unrelated conked out. Coincidence?
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Old 06-08-2008, 05:23 PM
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Once a Kia starts to get the electrical gremlins, just get rid of them, it's not a matter of if it will get them, it's a question of When it will get them.. The harnessess short out at diffrent places and cause all kinds of grief. My brother had to stop driving his ('01 Sephia ) because of electrical problems that were effecting everything.
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Old 06-08-2008, 05:36 PM
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Does it have an oil pressure switch so the pump won't run without oil pressure?
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Old 06-08-2008, 06:00 PM
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Quote:
Originally Posted by elliott
Does it have an oil pressure switch so the pump won't run without oil pressure?

I don't know but that's a good question because it sure seems like something is telling the computer not to ground the relays. I an SURE the wiring is OK from the computer to the relays and from there back to the pump but the computer refuses to ground the darn things. I have double checked the grounding wires from the computer to the chassis so I know that is OK and the computer itself seems to be working OK because it will power up and scan just fine and it does not show any trouble codes. Since the system does not go through the pre-start fuel pump run cycle I would suspect some kind of inertia switch but I sure can't find one if it has it.
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Old 06-08-2008, 07:47 PM
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Quote:
Originally Posted by elliott Does it have an oil pressure switch so the pump won't run without oil pressure?
Hey elliot, what kind of cars have an oil pressure switch like that?
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Old 06-08-2008, 11:49 PM
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Quote:
Originally Posted by scrot
Hey elliot, what kind of cars have an oil pressure switch like that?
I don't know honestly, never came across one that I know of. Like he said something is telling the computer not to ground the relays, outside of an oil pressure switch or an inertia switch, I couldn't imagine what it is.

Might want to try posting here, there are some Kia techs that are members, if anyone would know, it would be them.
http://www.kia-forums.com/
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Old 06-09-2008, 05:03 AM
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Quote:
Originally Posted by oldred
. Since the system does not go through the pre-start fuel pump run cycle I would suspect some kind of inertia switch but I sure can't find one if it has it.
Look for a rubber black button in the engine compartment.
Last one I found was on the passenger rt frnt inner fender near the air intake hose.
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Old 06-09-2008, 06:49 AM
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Elliott, Thanks I went over there and registered and posted this question so maybe someone there will know. I did a search before asking and WOW! Just as I suspected those things are notorious for electrical problems which should not have surprised me after working on this POS. The first problem was the fuel gauge sending wires had heated and MELTED! inside the tank because the fuel pump ground wire had lost ground and the fuel pump current was flowing only through the sending unit ground, a tiny 20 ga wire. This occurred because the fuel pump ground wire was nothing more than a wire attached to the floor sheetmetal by a small Phillips head sheetmetal screw and they had not even removed the paint underneath! This "connection" had become loose and corroded and lost contact leaving only the tiny fuel sending unit wire to carry the current which should have been isolated from this wire anyway for obvious safety reasons. The main ground from the battery is just as bad since the chassis ground is attached to the battery box of all places which is simply bolted to the inner fender, these mounting connections are (were) corroded badly which is not surprising. These problems were repaired the first time around a couple of months ago and they were the first things checked this time but all seems to be good there unless I am missing one.


Thanks to everyone and I will get back with what I find on this thing.
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Old 06-09-2008, 07:09 AM
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I could never own a car called a KIA, for obvious reasons .

Vince
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Old 06-13-2008, 03:58 PM
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I went to that kia web site and although they seemed like they wanted to help (friendly bunch of guys over there ) they were as puzzled by this as I am. Today out of desperation I decided to check every sensor on the darn thing that I can check here is what I have found. There is a small plastic gadget held onto the top of the fuel pump assembly on the tank called a fuel tank pressure sensor which has three contact pins in it. I got the resistance specs for this thing but when I checked it there was nothing, it is completely open between all contacts. Obviously this part is bad but would it have anything to do with the computer signaling the fuel pump relay? I asked a guy in the service department at the Kia dealer and he said that it is an emissions device and should not have any effect on the problem but it sounded to me like he was uncertain. Well this little itty bitty plastic gizmo that probably cost all of .50 cts to make is dang near $200 and I can't find one in a wrecking yard, at least not one they are willing to sell off the fuel pump unit. I am trying to keep the cost down on this because the girl who owns it really can't afford to spend another $200 on something that will not solve the problem besides the fact that she would be getting ripped off big time! What do you guys think, could this thing have any bearing on the problem?
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Old 06-13-2008, 04:24 PM
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I know you can usually expect BIG problems when redesigning a system, but....

Is there any easy way to devise a pump power system that allows the pump to run during cranking, but then needs a signal from elsewhere to keep the pump running AFTER it starts? The 70 VW I drive daily is like that. It's pump can be wired to run all the time if the motor is running...mine is.
Mine should have the timed delay relay hooked up, so the pump only runs for a short while if the key is ON, but not cranked. Some PO did away with that, and in case of a crash, it will stay pumping.
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Old 06-13-2008, 04:30 PM
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I have been thinking along those lines but I would like to exhaust every other possibility first. Right now I am considering wiring in some resistors of the correct values and tricking the computer into thinking the sensor is there however I am not sure if all three wires would need these hooked up at the same time?
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Old 06-13-2008, 09:58 PM
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What year and model is this KIA?
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Old 06-14-2008, 06:53 AM
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2001 Sportage., there was a mid year change for the computer and the mfg date on this one is post 6/15/01.
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