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DaveJr

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Discussion starter · #1 ·
Yes, I'm a newbie. I should spend hours using the search functions and YouTube, and I have. I cant find the exact issue anywhere.
I purchased a 94 Grand Cherokee Limited w/ a 5.2 for cheap a couple weeks ago. The anti-theft system was butchered when I got it, but it ran...until three days ago.
I can no longer hear the fuel pump run. Now the question is, is the fuel pump tied into the anti-theft system ? I've tested the relay socket, and it's fine, and swapped out the relay, still nothing.
Am I missing something ? Am I just screwed since the anti-theft has been jury rigged???

Any ideas or advice would be greatly appreciated
 
Hey DaveJr, I think it is great you are working on your jeep yourself.
If you search Pacific Coast Manuals on the web a great factory manual can be downloaded for about $8. You won't be disappointed! Tons of info...about 2k pages.
Try this first, I call it a master reset. Disconnect the battery and touch the two leads together for 10 seconds. This will reset all the control units and remove any corrupt data.
The battery failed on my 5.9 and after jumping it, the engine would not run. A master reset fixed it.
I haven't studied the jeep alarm system yet but I can help a little with the fuel system.
You said the fuel pump relay socket was checked, I'm not sure what that means to you. Yhe function of the socket must be checked. You will need a test light or volt meter. There are two circuits used by the fp relay. One turns the relay on and off and the other connects the battery voltage to the pump. The small outer two pins on the relay are the control pins and the two larger pins are for the pump.
At the fp socket you should have battery voltage all the time at one of the large pin sockets, if not check the fuse or wiring. If you jump the two larger pins in the socket the fuel pump will run. If not smack the bottom of the fuel tank...the pump may be bad and stuck and smacking the tank may get it running. If the pump runs see if the engine starts. If it doesn't, the alarm may be stopping the ignition or injectors.
To check the control side of the socket you must check for battery voltage at one of the outer small pin sockets when the key is in the run position. If not check the run fuse. The ground side of control circuit is supplied by the fuel injection ECU. Connect your test light lead to the positive side of the battery and probe the other small pin of the fp socket. The light should shine when you crank the engine. Good luck! Denny
 
Discussion starter · #5 ·
Thank you sir for your help. I'm not sure exactly how it happened, but I have my ZJ running.
I did what you z
Suggested with the battery cables, then I turned on the ignition switch for about 10 minutes, heard the fuel pump cycle, and it fired up.
Again, thank you for the assistance, and hope I can repay it someday.
 
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