Leftty57

Can Someome Help!! me?
I was recently sitting in my 2000 Jeep Grand Cherokie 4.7L vehicle. It was in idle and parked. When suddenly it just cut out. There is NO Check Engine light or code to be addressed. There was no noise, no shimming, no nothing I hardly noticed it turned off it was more like if a fuse went, or some kind of power cut off. I checked the fuel line..No fuel pressure or fuel in fuel line, so I checked the fuel pump by turning the ignition and could Not hear the fuel pump engaging so I hot wired the fuel pump to test it, and it works. Then I checked the fuel pump relay, and the ASD relay and switched them around since I have more than one of each and nothing. Next I checked the fuses.."All Of Them" especially the fuel pump fuse and all are good. I replaced the crank sensor with a new one since this can cause the fuel pump to cut off if it gets crossed internally. I also have no working Gas guage, and no batt guage when I turn the key (initially that's why I changed the crank sensor. So far everything I'ved checked is working order except I still have no power going to the fuel pump.

94 purple zj

Hmmm. U got me i was goin to say fuel pump relay but u got that. U said u got poer to it from jumping it from 30-87? If so there has to be a issue with the relay. The other relay u tested could possibly be different in some way??

Leftty57

Thanks for reply, I jumped the fuel pump right from the gas tank from the plug. The relay seems to be good since I switched it with the other like relays, (I have a few of the same) and they are working fine, but won't work on the fuel pump.

Leftty57

I will try to jump it from the 30-87 and see what happens later on today.

94 purple zj

Ya do that and let me know.. u just need a paper clip bend it and put in both 30 and 87. The key will not even need to be on. As long as the jeep has power u dont need the keys.. if it dont kick on like that then its got to be a short from the relay to the plug on the pump.. or it just might be goin out. I know that if u beat on the tank sometimes u can get a little more out of them but they do funny things wen they go out. If the fuel guage does not work thats a first sign.

Leftty57

Ok, I jumped the fuel pump relay from the relay/fusebox and the pump does go ON. I now have fuel in the fuel line all the way to the injectors, but still I can only get the engine to crank, there is no attemp from the engine to start. So far I had installed a new Crank Sensor, so where does this leave me now?

Leftty57

I have read in other post that the crank shaft sensor will also kill the gas guage and the battery guage when gone bad, and will make engine just crank, ( I've had issues with crank shaft sensors before on this and on my other vehicle, so im well aware of crank shaft symptoms) the only issue I have with this is that a crank sensor acts up some what before it totally goes out, Example: engine misfire, hesitation, but never stoping the fuel pump. I also had this CSS go out on this vehicle years ago but it let me drive for a while with a miss due to poor fuel burning, it didn't cut out the engine like this issue I currently have, but it was not until I shut it down that it would not start. Also crank sensor when engine is cold will sometimes let the engine start and run until it gets hot then it will cut out the engine due to a bad crank sensor.

94 purple zj

Ok but did u try to start it with the relay jumped or with the relay in? I thought the actual relay was not kicking the pump on?

Leftty57

I tried to start it with the relay jumped.

Leftty57

When I put in the relay the pump won't go on

Leftty57

I switch relays and none will make the fuel pump come on.
But fuel pump relay works on other components. Like wipers, And horn, ect.

94 purple zj

Lol thats ur problem... i would pick up a new relay from even a junk yard. I know other ones did not work but may be diff internally.. i am suprised i didnt fry the whole box tryin to crank it jumped.. it was sendin wayy to much fuel wen it was jumped so probably fluded it..

94 purple zj

Actually i am thinking u lost a ground on the underside of the fuse box for that relay.. when u jump u bypass all that.. i would pull the box up and look at the wires goin into the box to that relay..

Leftty57

Ok b4 I go get another relay I will pull the box and check for ground wires. The reason I'm switching relays is because they are identical in serial number or say part number. All the ones I'm using are an identical relay. I thought maybe flooded but it didn't even try to start. But when I spray starting fluid it reacts to that so I think I may have some spark. Also im going back to pull out the starter to get to the crank sensor to make sure it has a good connection.

Leftty57

I pulled the starter and checked the crank sensor connection and it is properly connected. Next I pulled the relay box and checked that all connections are good on the underside "everything looks good" and tight. I unmounted my dash and checked all fuses to alarm, cutoff system, and auto start all are ok. Then I cranked the engine to try to get a code. I got a code 1767 "transmission Relay always on". Do you know if this can cause this issue?