Jeep shut off while driving and will not start.
Thread Starter
Newbie
Joined: Apr 2019
Posts: 13
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From: Upstate NY
Year: 1992
Model: Cherokee (XJ)
Engine: AMC 4.0L HO
'Crank but no start or fuel pump prime.'
It is easy to see and verify wether your crankshaft position sensor is okay or not, to help eliminate it as the reason.. But, a faulty CPS sensor is not going to shut off the fuel pump.
I would verify and make sure the fuel pump truly is not priming. You can take off the gas cap and stand with your ear to it listening while a helper turns the key to the starting position for you. Or, you can use a DVOM to check for and see if you are getting 2 seconds of power at the fuel pump during the priming cycle as your helper turns the key forward into the starting position for you? You can check the pressure at the fuel rail for getting a proper prime too.
It is easy to see and verify wether your crankshaft position sensor is okay or not, to help eliminate it as the reason.. But, a faulty CPS sensor is not going to shut off the fuel pump.
I would verify and make sure the fuel pump truly is not priming. You can take off the gas cap and stand with your ear to it listening while a helper turns the key to the starting position for you. Or, you can use a DVOM to check for and see if you are getting 2 seconds of power at the fuel pump during the priming cycle as your helper turns the key forward into the starting position for you? You can check the pressure at the fuel rail for getting a proper prime too.
Banned
Joined: Feb 2019
Posts: 1,359
Likes: 169
From: NC
Year: 2004
Model: Grand Cherokee (WJ)
Engine: 4.0
You have to trace it back to the point in which you find where the power abnormally terminates, back from the inoperable fuel pump is one way to find out where the power stops? The relays send power to the pump. The relays get it from the fuses. It sounds like the fuse for the fuel pump relay is new and is good.
If you check for power at the fuel pump relay terminal during priming, you will know if power is getting there up to this point.. or not?
If you check for power at the fuel pump relay terminal during priming, you will know if power is getting there up to this point.. or not?
Thread Starter
Newbie
Joined: Apr 2019
Posts: 13
Likes: 0
From: Upstate NY
Year: 1992
Model: Cherokee (XJ)
Engine: AMC 4.0L HO
Definitely double check that crank sensor. My Sport dropped dead on the road and I coasted into a parking lot. I bought the lesser-costing sensor and replaced it. It got me three miles closer to home and also failed. I spent the big bucks ($75.00) and replaced it again. That was a couple years ago now. So far, the sensor is working fine. When a truck ignition just dies like that suspect the crank sensor 1st and don't go cheap.
Thread Starter
Newbie
Joined: Apr 2019
Posts: 13
Likes: 0
From: Upstate NY
Year: 1992
Model: Cherokee (XJ)
Engine: AMC 4.0L HO
You have to trace it back to the point in which you find where the power abnormally terminates, back from the inoperable fuel pump is one way to find out where the power stops? The relays send power to the pump. The relays get it from the fuses. It sounds like the fuse for the fuel pump relay is new and is good.
If you check for power at the fuel pump relay terminal during priming, you will know if power is getting there up to this point.. or not?
If you check for power at the fuel pump relay terminal during priming, you will know if power is getting there up to this point.. or not?
The relay that connects to the fuel pump spikes in voltage when the key is turned, then drops back down to what it should be normally after i think 3 seconds or so, like the internet has told me.
Banned
Joined: Feb 2019
Posts: 1,359
Likes: 169
From: NC
Year: 2004
Model: Grand Cherokee (WJ)
Engine: 4.0
This means you have power to that point. For the fuel pump, something between here at the fuel pump relay and the fuel pump is not right.
Is the relay the problem? Did it click.. did you hear it, or feel it click between your fingers with having a helper turning the key for you? That is not a conclusive test though. You can try swapping a known good relay into its place, to see if it works or not? If you do, just do not use the ASD relay as it will not be specific if it does not work to run the pump if it is actually the reason. You can pull the relay and test it on the bench to see.
There is proper power at the fuel pump relay, so the fuel pump being inoperable is due to a reason between the pump and here where we know the power is currently able to get to, for the pump.
Knowing wether you have spark or not is very helpful to know.
CF Veteran
Joined: Mar 2016
Posts: 3,816
Likes: 725
Year: 96
Model: Cherokee (XJ)
Engine: 4.0
there is a connector near the fuel tank, I would check for 12V there..and a good earth
Junior Member
Joined: Aug 2019
Posts: 63
Likes: 2
From: Brisbane
Year: 1995
Model: Cherokee (XJ)
Engine: l6
Hi Cruiser54
I just want to say thank you for sharing your wealth of knowledge over the years!
I have owned and loved a 1995 Xj Sport RHD ( being in Aussie Land ) It was a company vehicle
for the first three years of its life then I bought it ! I am in my 70s now and have owned many vehicles
but the XJ has a place at the top of my list!!
Over the years I have been glad to have you at my elbow!!!
All the best and good health to you
silverfoxxj
I just want to say thank you for sharing your wealth of knowledge over the years!
I have owned and loved a 1995 Xj Sport RHD ( being in Aussie Land ) It was a company vehicle
for the first three years of its life then I bought it ! I am in my 70s now and have owned many vehicles
but the XJ has a place at the top of my list!!
Over the years I have been glad to have you at my elbow!!!
All the best and good health to you
silverfoxxj
Last edited by SilverfoxXJ; Jan 9, 2023 at 01:41 AM. Reason: not correct tag
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