RockyMountainXJ

so i just barely bought a 97' cherokee sport. i notice it had kind of a low idle when starting up but got better as i started driving, well i drive it home(about 40 miles) an park it in my drive way. i turn the engine off an go inside for about 10 minutes an then come back outside to pull it under the car port, i go to start it and it will crank but wont fire up. i try again i turn the key it starts to crank, i give it a little gas and then it fires up. as soon as i took my foot of the gas the idle went down to about 300rpm and then just died. so the only way i could get it started was by giving it gas while cranking and giving it gas while it idled to keep the rpm's higher. so i was thinking maybe dirty fuel filter or something. i have cleaned my throttle body, i have taken out the fuel pump and the fuel pressure regulator/filter that is on top of the pump and cleaned it all and put it back in. but now i dont think im even gettin fuel to my engine cause it wont fire at all now even with me giving it gas. i tried starting fluid, it fired with that but then died as soon as it burnt up all the fluid.... so any suggestions? any one have a similar problem please help.. i dont know if its my fuel pump, or my pressure regulator that isnt working. i dont want to replace parts that arent broke so if there are any test that i can do that dont require the engine to run please let me know thanks.

moparboy

First and foremost, spraying starting fluid into the throttle boddy can give a "false positive" regarding whether or not this is a fuel system issue. Starting fluid alone could start a gas engine as long as there's enough compression and you have hot plug leads after a drive, or even a weak spark. Starting fluid works really well on diesel engines because the compression alone will squeeze the mixture enough to start, or kinda/sorta start a diesel engine. A gas engine can react in a similar manner if the plugs are still hot, despite the fact the two engines work off different principles.

First and foremost you have to determine if this is a fuel issue or one which involves your ignition system. Check for a good, blue/bright spark after a long drive when this problem starts, then get back to us. I have a hunch I might know what your problem is although we won't ba able to help you too much without more info.

Good luck.

RockyMountainXJ

everything is now back in an now when i go to start it it just cranks wont even fire up if i give it gas.. i think the fuel pump has gone out cause there is no throttle response and the system is not getting pressurized

RockyMountainXJ

well i think my fuel pump is shot.
There is no pressure getting to the fuel rail.
I dont hear the pump working when i turn the key to accessory(which should send the signal to the pump to pressurize)
So either the pump is bad or there is a bad fuse or relay somewhere..

tjwalker

By design, the fuel pump should energize and run for approximately 2 seconds when the key is turned to the ON position.

If yours isn't doing this, it could be the pump itself, but before condemning the fuel pump, you should rule out the "control" electronics for the pump.

Start by temporarily swapping out the fuel pump relay with a non-critical relay like the e-fan. The relays are located under the hood in the power distribution center (black box) on the passenger side. These relays are all of the same part number, so they can be swapped safely.

RockyMountainXJ

well heres the update:
I got it running i can start it and let it idle without giving it gas now. there was a disconnected wire on the connector that goes to the pump so the pump wasnt gettin power, we fixed that so we got fuel pressure to the rail. bought a new battery as well went to autozone and got it tested they said it fail so have a new one now.
but we have come to another problem..
There is a vacuum port on the intake manifold that has a hose connected to it this hose runs from the intake manifold around the left of the engine back and connects to a sphere type part(i have no idea what this part is) but we believe whatever is in the sphere is clogged. when we disconnect the hose the idle rpm goes up to about 650rpm. when we connect the hose back on it goes back down to 450 or 500ish..
Does anyone know what this sphere type part is? i believe it has something to do with the vacuum emissions system plz help if you have any input
Thanks, jordan