1993 jeep grand cherokee

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  #1  
Old 04-05-05, 09:15 AM
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1993 jeep grand cherokee

I've recently started having a problem with starting my jeep. About 4 months ago my fuel pump quit making noise "every" time i turned the key over. and it was also taking longer to start(i would crank the engine for 5 to 7 seconds, and turn the key off, crank again 5 to 7 secs, and turn key off. sometimes it wouldn't start til the third or fourth try). but in between starting and turning the key off, it would always start after i heard the fuel pump whirring noise. so i decided to change the fuel pump which left me with the exact same problem that i had before. i went to the auto store and borrowed a OBDII scanner and it read no codes at all. yesterday i just stumbled upon how to get the fuel pump to work everytime i turn the key over. If i turn the key one and let the jeep sit between 30 to 40 seconds later the fuel pump will finally kick on. then it'll start fine. I'm wondering why all the sudden it's starting have this delay to get the fuel pump to work. I've already changed the fuel pump relay and one more relay, can't remember which one right now. i would also like to know what makes the fuel pump kick on to prime the fuel lines? is there a couple of things that it senses before it kicks on? if so one of those might be bad. anyway, someone please help, i've been battling this and wrecking my brain for 4 months now and would like some help. thank you.
 
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Old 04-05-05, 11:18 AM
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had a buddy with a bad wire to the pump,didn't act just like your but was slow to start
 
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Old 04-05-05, 02:18 PM
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how should i go about checking to see if there's a bad wire? continuity check or reading voltage when i start the engine or what? (if you know)
 
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Old 04-06-05, 04:29 PM
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I think you have a problem with the tank, for some reason, the tank got some sort of contaminates with gas/additive at the pump, if you gas looks kinda redish and feel some what "slimy" when wipe the inside of the with a finger, I have seen dozens of those incident, the fuel pump kinda sticky when vehicle has been parked for period of time and that causing the hard/long crank condition, when it's started, it'll OK until the next parked.

You can try to drain all the gas out and clean the inside of the tank real good, let it dry and refill with fresh gas using the old pump and see if it's helps, if it does and if it's happened again later on, you may need to replace the tank.
 
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Old 04-07-05, 04:55 AM
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start at the tank connector...

...and check for voltage when the key is turned on (2-3 seconds). if you don't have voltage there, go back to the relay and test for voltage coming out of the relay. this will get you started eliminating things...
 
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Old 04-20-05, 06:41 AM
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here's change one to what's happening

my jeep is still having the problem of getting it started. but have found out that the fuel pump doesn't activate until the check engine light comes on when i first turn the key over. so now i need some help to find out what sends the signal to the check engine light and fuel pump to activate it. i've read out both fuel pump relay and Automatic Shutdown Relay (ASD), both check good at the relay box, and also just to be sure I bought both two new relays. I'm pretty positive that the problem is with the "check engine light" signal being sent. but i can't find a schematic in detail enough to find out where the fuel pump actually get's the signal of when to kick on after the key get's turned over.
 
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Old 04-20-05, 06:51 AM
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the ECM...

...or engine controller grounds both the lamp and the fuel pump relay. this completes the circuit to ground and allows operation of the circuit in question (this is the most common control method in automotive electronics). power is fed to the engine controller by the ASD relay (along with a quite a few other devices). simply replacing the relay doesn't completely rule out a connection issue within that circuit. some very specific pinpoint testing, at the relay and probably at the controller seem to be the next step. this may be the pooint at which you need to decide to take it to a pro...a good understanding of circuit operation, wiring schematics and test performance are critical.
 
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Old 04-21-05, 03:07 PM
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i figured that much

I called the dealership and they told me it was $80 to hook it up to the diagnostics machine to pinpoint the problem a little better. I figured I'd probably have to end up doing this eventually, but thanks for the advice. The thing that really bothers me is getting ahold of a detailed schematic of the electrical system is hard, if not impossible without paying to much money for the O.E.M. version. But thanks for the advice.
 
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Old 04-22-05, 03:30 PM
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jeep

If your vehicle is equipped with anittheft system you probably have a bad sensor. Check the one on the top of the passnger side fender under the hood first. The jeep GCs of this vintage were famous for getting hood misalingment and causing false alarms.
 
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Old 04-23-05, 02:26 AM
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anti-theft sensor

is this something that would cause a delay in the fuel pump circuit? just one bad sensor. another question now that we're talking about the anti-theft. when i unlock the door from the passenger side, it doesn't turn off the anti-theft, when I open the door the alarm goes off and I have to run to the other side and unlock the driver door. so that would probably explain the reason for the jeep doing that, but is it possible to be messing up the fuel pump?
 
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Old 08-15-06, 01:23 PM
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Hey guys, I know it's been a long time since I posted on this issue, but I finally found the problem. Or the dealership did. It turned out being the PCM, so it cost me around $1000 to have them get me another one (refurbished, yeah :P) from detroit and replace it. Since then I've had no problems with the fuel system, well except for leaky and cracked fuel injectors. Those all got replaced for $300, I did that one. But the jeeps came a long way, drove it from Florida to Texas, where I now live without any problems. The latest I just tackled was the Air conditioning system. I replaced a bunch of parts on it, $900 for just parts, but she's blowin cold for the mean time. Anyway, thanks for all the help that I was givin on this post, I just wanted to let everyone know the result for future reference/help of others.
 
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Old 01-19-14, 10:24 AM
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Pcm

Is it located on the fire wall on the passenger side??
 
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Old 01-19-14, 10:44 AM
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This is a 9 year old thread. Hopefully they got it fixed.
 
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