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Tuzmaster 02-22-2013 09:31 PM

My dads Jeep
Alright so my dad has a '99 Grand Cherokee Laredo with the 4.7 V8 and almost 210k miles on it and now came a problem. When driving, the rpm would go up to a certain point and then drop causing the car to sow down. idk what the problem is but basically the car would not accelerate. we changed the fuel filter and it seemed fine for the night, but next morning it started again. It does not stall; just doesn't accelerate and the check engine does not light up. Any suggestions guys? Need advise ASAP

Frango100 02-23-2013 02:08 AM

Re: My dads Jeep
Could be the fuel pump which is on its way out. You have to measure the fuel pressure at the fuel rail, to know if the problem is the pump. The pressure should be 49 +- 5 PSI.

Tuzmaster 02-23-2013 11:24 AM

Re: My dads Jeep
I should add that the power cuts off between 1000 rm and 3000 and there is no connection between any of them. While driving if park for a lil bit, then you can drive again, but not for very long.

Frango100 02-23-2013 02:30 PM

Re: My dads Jeep
So did you check the fuel pressure?

Tuzmaster 02-23-2013 02:31 PM

Re: My dads Jeep
no not yet but it looks like the pump. a friend of mine had a similiar thing on his explorer

Frango100 02-23-2013 02:42 PM

Re: My dads Jeep
To change the fuel pump, you have to drop the fuel tank. I did it once and you can replace the cartridge (the actual pump) from the tank unit. I can get you the Bosch P/N if you want to have it, took some pictures when i opened up the unit.
Eventhough not a too difficult job to do, it will take you between 6 and 8 hrs to finalize it.

Tuzmaster 02-23-2013 02:45 PM

Re: My dads Jeep
sounds about right. could you send me a few pics of how you did it man? i would appriciate it a lot. and whats the Bosch P/N that you are talking about?

Frango100 02-23-2013 03:24 PM

Re: My dads Jeep
3 Attachment(s)
Yeh sorry, Bosch is the brand of fuel pump installed on my WG. It can be that yours has a Denso or other brand, but they should just fit.
I found a few pics of the unit and the pump itself. The Bosch pump has P/N 0 580 453 431
If you decide to change the pump, you could ofcourse buy the complete tank unit with float, but its a bit expensive. Also before dropping the tank, take as much fuel out as possible, because its all weight you will have to work with.
I reused the seal from the tank unit, but its maybe a good idea to change it, to prevent leaks afterwards. I probably can give you more directions regarding the job (if i still remember:o), which i will give you as soon as you have decided to do the change.

Tuzmaster 02-23-2013 03:46 PM

Re: My dads Jeep
Ok awesome thank you!! I do not know when my dad plans on doing it but most likely tomoro, not sure. February 24th that is

Frango100 02-23-2013 04:54 PM

Re: My dads Jeep
3 Attachment(s)
Ok, i will see how far i remember this case. First you have to be sure that the tank is not full and preferably close to empty. When it is too full, besides that it is too heavy, also fuel can spill out as soon as the tank unit is removed. So use a hose and syphone it out as much as possible. Be carefull with the fire risk. Now you have to release the fuel pressure. Take the fuel pump relay out of the PDC and start the engine. It will run for some seconds and then die, due to low pressure.
Now disconnect the battery negative cable for safety.
Now you have to remove the plastic shield from the aft side of the left rear wheel well. There you will find some hoses which are connected to the tank. Remove each of them and then loosen also the refuel hose. I took it of together with the metal refueling connector. Now from underneath you have to remove the hoses to the fuel filter. The connector from the fuel pump will be removed after you have lowered the tank enough to get access. Now you can loosen the bolts of the tank protection shield and lower it. You will see the fuel tank now, still hold in place with 2 large bands and 4 bolts. Now you have to put a jack under the tank (preferably one with wheels) and a large piece of wood to devide the weight better. When the jack is in place, remove the 4 bolts of the bands and slowly lower the tank. Watch out for any forgotten line and that the wiring will not be stretched. When i remember well, i could disconnect the fuel pump/level sensor wiring connector with the tank almost on the ground, but verify this on your rig, to prevent extra work of wiring repairs:rolleyes:.
Now you can remove the tank from under the jeep. You will see a lot of dirt and stuff on top of the tank, so maybe a good idea to clean it before opening the tank.
You will see a big round white unit with a large plastic nut. There seems to be a special tool for that nut, but i just gently tapped with a blund tool, so that it came loose. Now the whole tank unit can be removed, but take care of the float arm, so that it will not be bend.
Now with the unit on the bench, you better first remove the float assy from the pump housing. Take pictures now and then, which could add in assembling, in case you forget how it was looking before.
Now with the aluminum canister in front of you, you will see the plastic cover which closes it of. This cover is held in place with some small fingers on the side of the canister. Gently push them in and at the same time pull the cover up. Bit by bit the cover comes loose after pressing all fingers. From now on it will not be easy to describe, its a bit too long ago when i did mine. But you will have to disconnect internally the connector on top of the pump. You can now change the cartridge and build it all up again. In the top part of the unit is a seal, which should be lubricated with a bit of petroleum gelley (see first picture). This is because at the moment of installation of the unit in the tank (fastening the big plastic nut), the unit will be spring loaded, to fit snug inside the tank. At this moment the seal will have to slide a bit and the gelley will make this easier. There is also a pointer on the tank unit (second picture), which should aligh with the 3 stripes on the tank, preferably with the center stripe. This is to be sure that the float can move freely over its full range.
The installation is the reverse of the story. Success.:thumbsup:

Tuzmaster 02-23-2013 06:34 PM

Re: My dads Jeep
Awesome thanks man. my dad told me after i'm done with the hw to start on removing it so ill be going with these instructions. great deal. will let you know if the pump was the problem. it sounds like it but can never be 100 % sure untill you did it

Gus9890 02-26-2013 03:35 PM

Re: My dads Jeep
Sounds like a fuel pump issue, easy to change out.

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