05 JEEP TECH QUESTION

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WAYNE0

WAYNE0

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This a long one. Ill try to make it short as possible. I have a 05 jeep g. cherokee 5.7 In November it started no starting & i noticed i couldnt hear the fuel pump. It would only do it once in awhile. So i changed the fuel pump relay & fuse. It was fine for a few weeks then back to not starting. At that time i noticed my battery was going bad & i was told the pump wasnt getting enough volts. I then had the alternator tested & it was bad. I replaced battery & alternator. Again it was fine for a few weeks. This was all it or miss. It might start for a few days or a few weeks. Again i knew when it wasnt going to start because i couldnt hear the pump. I replaced the relay & fuse again. Once again it was fine for a few weeks. At the end of December i replaced the fuel pump. It was good until April. Back to not starting. I replaced the fuse & switched the relay with another one from in the fuse box. Fine for a week. I went to visit my mom the other day. I visited for a few hours. It wouldnt start. I switched the fuse & relay from others in the fuse box & nothing. I went in sat down for about 10 minutes. Went out & it started & it idled really ruff for about 5 seconds & shut off. Havent been able to start it since. Im lost. If its electrical im screwed lol When it comes to wiring testing & checking i am a dumb ***. lol Sorry so long. Thanks
 
I assume it cranks but does not start?

If you can be 100% sure it is the file pump not running that is causing the no start issue. You could rest it by temporarily running a wire jumpering the fuel pump directly to the battery with a switch.

Next time it happens flip the switch, if it starts you have isolated the symptom and can start working on a solution.

You could also bring some starter fluid and spray it in when it doesn't start.


Most FI cars have an inertial switch to kill the fuel pump in an accident. It might be failing

Another thought is anti theft system???
 
Dana67Dart said:
I assume it cranks but does not start?

If you can be 100% sure it is the file pump not running that is causing the no start issue. You could rest it by temporarily running a wire jumpering the fuel pump directly to the battery with a switch.

Next time it happens flip the switch, if it starts you have isolated the symptom and can start working on a solution.

You could also bring some starter fluid and spray it in when it doesn't start.


Most FI cars have an inertial switch to kill the fuel pump in an accident. It might be failing

Another thought is anti theft system???
Click to expand...
yes it turn over
 
If you can't learn to deal at least with the basics of electricity you are likely wasting your time--and money. What I'd do based on what you said
1...Buy or borrow a scanner and see if you can find some errors. Some of the parts stores loan or rent scanners
2....Round up some documentation, see if you can find a manual on line. There are several off road/ Jeep forums, but I don't know where to point you
3...Consider buying a relay socket pigtail that fits the pump relay, then get some male spade/ flag connector terminals, and terminate the relay pigtail wires so you can plug them into where the relay "came out of." This will allow you to probe the relay socket easily and determine if the relay coil is getting grounded (if it is switched,) if the relay coil is getting power, and if the contacts are sending power at least "towards" the pump. You can also jumper "around" the relay contacts to try and activate the pump.

Not knowing the connectors under the Jeep or downstream in the harness, it could be a loose/ intermittent/ bad connector, etc

The chances of more than one relay or pump failing is zero. I suppose it could happen, but the chances are very very slim.
 
No inertia switch in 05 Grand Cherokee, anti theft would prevent cranking. Could be lots of different things, that require various ways of testing and some electrical smarts. Examples - crank position sensor, cam sensor, either can fail without setting a fault code. Wiring - corrosion almost anywhere in the harness. Also, depending on where the OP got his parts - they could be inferior / failing right out of the box. Look up how to bypass a relay, and try that, make sure the terminals that the relay plugs into are tight fitting. I wouldn't recommend throwing any more parts at it without an accurate diagnosis. Sometimes we can help, other times, you just need to bite the bullet and take it in.
 
Our 07 Hemi Durango was doing something similar. It was a bad fuel pump. Before we replaced it, we could beat the bottom of the fuel tank with our hand and it would make it start. Once it started, it would stay running.
 
Scan it for codes , is the or does the check engine light come on or is on ?
 
first scan for codes, and fix the codes directly.

2nd, if all else fails, I have fixed weird "no code" problems in my 04 grand cherokee by disconnecting the battery and cleaning it, double checking my grounds, disconnecting the ecu cables 1 by one (really important to have battery disconnected) and removing fuses and relays 1 by one and cleaning all the contacts with a pencil eraser.
sounds stupid but it's worked for me. a lot of the electrical problems I've faced have been really simple things that cause a lot of weird gremlins

also, I am not sure how the fuel system works on an 05, but on my 04 I was having fuel pump issues where some mornings my jeep would turn on fine, and other mornings it would crank but not want to start until I tried a few times. Turns out the fuel filter has a fuel pressure regulator in it that had gone bad and it NEEDED an official mopar dealer replacement part because an aftermarket part only made it worse.
 
Several hot summers ago, in my 05 Ram, the interior AC fan stopped working. Next time I drove it it worked. This went on for a week or so until it finally quit for good. This should be simple I thought. Parts weren't too expensive and I wanted it fixed like right now. Got a new resistor, fan motor, and relay, thinking that should cover it. Wrong.
Turns out, I learned from youtube, it was the ignition switch. Not the key cylinder but the electrical box that the key cylinder plugs into and switches. It's a little, sealed plastic box. Nearly $200 from Chrysler. I opted for a cheaper one from the chain parts store. Well that one lasted about two months and gave up. Time to pay up for factory piece. Put that in and been good for several years.
I don't know if yours could be a similar issue but maybe youtube has some info.
 
Or . . . . If the jeep is equipped with a TIPM, it would have the fuel pump relay integrated into it. They have been known to cause intermittent no fuel pump issues.
 
The 2005 Jeep Grand Cherokee has 3 key Fuse & Relay components under the hood. The TIPM is the main Fuse & Relay box and is the most common source of failure. The Body Control Module (BCM) serves as the interface between the TIPM and the rest of the vehicle and also fails, but far less frequently.
 
Agree with Slick on this. Check where the wiring plugs into the bottom of the fuse/relay center. Those TIPM( Totally Integrated Power Module) are known for issues.
 
He stated that he has changed the fuel pump relay at least once, so apparently it is not internal to the TIPM. You certainly need to know what you don't have, fuel, spark, injector pulse, all three, and then go from there. Your problem may be a failure of previously installed part, or something brand new. I would take a good look at crank sensor.
 
65wgn440 said:
He stated that he has changed the fuel pump relay at least once, so apparently it is not internal to the TIPM. You certainly need to know what you don't have, fuel, spark, injector pulse, all three, and then go from there. Your problem may be a failure of previously installed part, or something brand new. I would take a good look at crank sensor.
Click to expand...
I would not assume that
 
Assume ?? Read his first post, he said he replaced it twice. Can't be much clearer than that.
 
Craig Burriss said:
Our 07 Hemi Durango was doing something similar. It was a bad fuel pump. Before we replaced it, we could beat the bottom of the fuel tank with our hand and it would make it start. Once it started, it would stay running.
Click to expand...
it has a new pump
 
Projectile Dart said:
first scan for codes, and fix the codes directly.

2nd, if all else fails, I have fixed weird "no code" problems in my 04 grand cherokee by disconnecting the battery and cleaning it, double checking my grounds, disconnecting the ecu cables 1 by one (really important to have battery disconnected) and removing fuses and relays 1 by one and cleaning all the contacts with a pencil eraser.
sounds stupid but it's worked for me. a lot of the electrical problems I've faced have been really simple things that cause a lot of weird gremlins

also, I am not sure how the fuel system works on an 05, but on my 04 I was having fuel pump issues where some mornings my jeep would turn on fine, and other mornings it would crank but not want to start until I tried a few times. Turns out the fuel filter has a fuel pressure regulator in it that had gone bad and it NEEDED an official mopar dealer replacement part because an aftermarket part only made it worse.
Click to expand...
mmm i dont even know where the filter is located
 
65wgn440 said:
He stated that he has changed the fuel pump relay at least once, so apparently it is not internal to the TIPM. You certainly need to know what you don't have, fuel, spark, injector pulse, all three, and then go from there. Your problem may be a failure of previously installed part, or something brand new. I would take a good look at crank sensor.
Click to expand...
would a bad crank sensor show up on a scanner if you hooked one up ?
 
I think I might try a temporary jumper wire(s) to the fuel pump if possible. I found on a van that seemed to be killing in tank fuel pumps, the lead actually corroded inside the length of the jacket. Once replaced, it was fine.

FWIW, on that crank sensor, if you do change it, sometimes they are a pain to remove. Some try to force them out and end up breaking them off. Scrape any paint or rust build up that can cause a bind on you. Use a penetrant to help "work" it out. Alot of people say to use the Mopar branded sensor for replacement. I used the NAPA (Echlin) with no issue.

tinman2 said:
Turns out, I learned from youtube, it was the ignition switch.
Click to expand...
Lol, a few years back, my '05 Ram could have the radio playing hours later after shutting down, as if the key was on "accessory". Unlock and open the door the "key in ignition" chimes start playing. If I smacked the dash bottom I could get the radio to stop playing and chime quit. Since I replaced the switch, it's been fine.
 
WAYNE0 said:
would a bad crank sensor show up on a scanner if you hooked one up ?[/QUOTE

Intermittent bad crank sensor will not always set a code. If vehicle is currently in a no start condition, then yes you could check the crank sensor output in the data stream, with a scan tool and see if it is giving a RPM count.
Click to expand...
 
Dana67Dart said:
I assume it cranks but does not start?

If you can be 100% sure it is the file pump not running that is causing the no start issue. You could rest it by temporarily running a wire jumpering the fuel pump directly to the battery with a switch.

Next time it happens flip the switch, if it starts you have isolated the symptom and can start working on a solution.

You could also bring some starter fluid and spray it in when it doesn't start.


Most FI cars have an inertial switch to kill the fuel pump in an accident. It might be failing

Another thought is anti theft system???
Click to expand...
Wrong.....most FI cars do not have a inertia switch
 
Just spray an alternative fuel source in the throttle body when it won't start and see if it will start off of that albeit it won't run long off that and at least then you will have determined that it is a lack of fuel and not lack of spark or communication issue or etc. You need to narrow it down somewhat and that is an easy way to cut part of the possibilities out of the picture. If it starts as someone sprays propane preferably, but probably not accessible to you, so maybe carb cleaner or starting fluid in throttle body and it starts and stays running as long as they continue to spray then check for power and ground back at the fuel pump connector with a Power Probe ideally and if you have both of those then put a new/better pump in it........it's pretty simple if you stick to the basics and not listen to every Tom, Dick and Harry that thinks they know what they are talking about.
 
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