Is it the fuel pump ? 2000 Grand

98Chero

New member
While driving my 2000 Grand to work each day, I have had the engine just stop while I was going down the road. It has happened many times lately. I replaced the fuel filter and it ran fine for a week or so. When it dies I put it in nutral and coast to the nearest shade off the road. Once I stop and put it in park the engine will restart and I am able to move down the road some more. It died on me 3 times this morning on my way to work and 2 times tonight on my way home. One time it stopped and I tested the fuel pressure in the fuel rail and it seemed to have plenty of presure in it. would the problem show up if I take it to a parts store that has a way to read the computer ? before a fuel pump quites will it "act a fool" like this before it finnally quites ? or should I be looking for something else.
Mike
 

Auto place cant use the computer because thier is no "check engine light on" I did get a fuel pressure rating, it should read 80 psi to 123 psi, thats seems pretty high but thats what it called for. Luckly I live in a rural area so I can keep driving it. It died twice on me today on my way home from town, the last time it died the whole jeep shook and jerked before the engine died ?. Its my day off today and if i cant get some clue what to do from this forum I will drive it to work where I have a fuel pressure gauge and see what it reads. Also the ASD and TCM relays are very hot to the touch compared to the other relays and fuses in the engine compartment.. again ?
 
Where did those fuel pressure specifications come from? I never heard of pressures like at for a six or eight cylinder . Defiantly get real fuel pressure readings with a proper gauge . Take more than one test . You'll want cranking pressure & running . When each test is done , try pulling the vacuum line off the fuel pressure regulator . The reading should be higher with the vacuum line off since the closed regulator creates a restriction and that will show that the pressure regulator is working. The auto shutdown relay and trans control module relay may or may not be related but we would need to see if the fuel pump relay is wired in series with these as the coil signal wiring ( terminal 85 & 86 ) for each relay may be in series. Did you notice of the fuel pump relay was hot to touch too ? Starting to wonder if there is an overdraw and the fuel pump electrical is starving for voltage causing the fuel pressure to drop . This is just a thought but an amperage test would have to be applied to the fuel pump wiring harness to check its draw. The ASD & TCM can be checked after that. Double check the shop specifications but usually around 40 psi or there of is typical . At least confirm steady voltage draw from the fuel pump harness while running but that probably can only be taken when jeep is idling and above idle but not moving unless it can be put on a dynometer for real world readings , hence a diagnostic session.
 
Greg, Thanks for your input. The fuel pressure specs came from the auto store's computer when we looked up the price of the fuel pump. I tested the fuel pressure today and it ran at 60 psi during start-up, idle, and high speed. On this model jeep 2000 grand Laredo 4.0 L auto 2 wd the fuel pressure regulator and the fuel filter are made together and located back at the fuel tank.while running the engine today i checked all electrical conections to see if it would make the engine stall or quit Nada. The ASD & TCM relays are the only ones that have a higher temp than the others including the fuel pump relay and fuse. It died on me once this morning on my 35 miles trip to work and did not die on me on my drive home this evening. I dont know what my next step is to do ? I kinda wish it would just die so I can track down the problem.
 

Your welcome for the reply. Thank you for the updated information as well. I'm sure that this problem would be one of those drivability problems where a diagnostic shop would run up a bill on dynometer time and offer to change the fuel pump and do further testing to see if the glitch and electrical overdraw still exists. The end result is $$ and no one will give a definitive answer until they perform the service. That leaves you being asked to agree with the diagnostic checks and no promise that the solution will be found. They will of course tell you they strongly believe what the cause is but can't confirm it until they get their hands on your jeep. Not to say they're is any dishonesty to start with but when they cannot support or justify their work and labor rate , that leaves you stick with the note. This happened to my dad with an E class Mercedes Benz once. He did get restitution but hassled and haggled over the bill. I don't want this to happen to you and I respect you turning to this forum ( or any other ) for your answer. Respecting your research and doing your homework , I'm only trying to draw from my experience as well. The only facts I can give from your up to date description of the problem leads me to believe the problem of fuel pressure is second to the electrical problem. In my mind , I'm thinking it sounds like some kind of restriction causing the fuel pump to work harder and drawing more amperage than normal which is causing a " blackout" in the wiring harness at triggers the ASD to shut down the engine . Even if a wiring diagram were to show the relationship of the wiring that is ganged together in the relay circuit ( a power circuit used to power the relay coils of several relays in a row) it's meaningless if the wiring is in good shape . This is only the effect that the relays are hot to touch due to the overdraw . You want the cause and need assistance to find it. I wish not to just appease you by understanding your grief and listening to your description of the problem but a solution would be good , agreed. Not for the sake of bragging rights do we want your jeep fixed but I hate when these things happen and are difficult to nail down. The only suggestion I have to offer is a righteous amperage test be performed to prove if/that an/a overdraw exists. That is the only way that one can proceed toward a repair. Before that however , it needs to be proven if a restriction in the fuel system in fact exists . Your fuel pump has not died altogether showing that replacing it may or may not be the answer. I realize there is a difference in design and that needs to be taken into consideration with regards to the check for fuel system restriction. If there is a restriction , where does it exist ? You already did the sensible thing of swapping the filter to eliminate that from the equation . Now , is the pressure at the rail acceptable is one question and is the pressure from the pump within range since pressure is normally lost from the pump to the rail. It has to be acceptable a loss to operate the system right however. If you think that speaking to someone at a trusted diagnostic center for known and proven case studies of this problem in your model and similar will help , that is a start. Also , if any Chrysler service bulliitins of this nature exist , that is more support toward a solution. I wish not to turn this post into a novel as I easily can but to offer a next step . Finding if a restriction exists and obtaining an amperage reading of the electrical draw the fuel pump is pulling to compare to normal draw readings. That I believe is what should be done after the Chrysler bulliitins are researched. If this happened to your jeep , it can't be an isolated incident. If your lucky , maybe a clogged pick up filter is the cause . Of course the tank on a grand Cherokee must be dropped and the fuel pump module is removed with special tools ( people makeshift this procedure though) but there is that to do just to find out if the pick up filter is the cause. I hope this post helps you to find the problem and hope that my offerings contribute to a real solution. Did I mention hard case drivability problems ? Who dosen't. A hard core tech invites them but Us diyer's are only so equipped. It's no fun when your under the gun. Hope for a solution to be found soonest for you . Thanking you for sharing this with us but sorry it's under these circumstances.
 
Ilł make this short for the sake of respect to your sanity . The only thinhg I can think of that may cause cause such a overdraw if is the case is line restriction ( I.e. Clogged pick up filter ) , possible grounding issues ( maybe ) or a bad in line electrical resistor. Hope this helps too.
 
Greg again Thanks for your input on my problem!. This morning and this evening drives to work the jeep did not die. so after the fuel pressure check and wiring exam the problem has went away. I dont beleive that I have fixed it just a temp pause till it shows up again. My 1996 cherokee had a similar problem and it turned out to be a quick connect wiring harness wire was broken after 200,000 miles and I found it by moving the wires around while the engine was running. I like your Idea about the grounding problem and the possible sock filter being clogged, also it wont hurt me to check the Chrysler service bulliitins to se if i can find something thier, I think I will try Chrysler service bulliitins online first. This morning I did stop by the auto store and bought a can of "HEET" I call it a mechanic in a can just to make sure it wasnt water in the fuel tank. I will keep you and others posted on this problem for the sake of helping somebody else in the future that may come accross a similiar problem.
 

Your most welcome . Hope that my suggestions may be helpful toward a solution for a final repair. Thank you for sharing with the forum as well since this is likely to be something that other jeep owners of your mkdel year and build and close to may have or possibly will experience. Thank you for thinking of your brothers and sisters in our forum . I'm sure the problem will be found but like all other hard case drivability problems , just will take more time and inspection. Happy it's running for you and still serves you . Will be looking forward to posts of your jeep . Thanks again , Greg
 
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