01 cherokee, was running fine 2 days ago, he changed trans fluid, filter, & bled the lines to flush fluid, & while bleeding it shut off, & hasnt cranked.

he wants me to look at it in the morning, but where should I look? or begin? he says he hears the fuel pump energize, but thats as far as testing as he has done, & says it has a coil pack? so he hasnt checked for spark. I havent looked at it yet, but would apreciate any pointers anyone could give.

how do you check for spark? I remember on some old GM cars using vacuum tube for short runs between coil towers & spark plugs, & then using a test light to short cylinders working with a skip, but that was back when the Quad 4 was new on the market. so I am sorely out of date.

Thanks,
Randy

 

No crank or crank and no start? If it cranks but won't start then check for spark (pull a plug and ground it to an engine bolt, watch for strong blue spark while cranking) and fuel pressure (will probably need to rent gauge).

If it's a no crank, check power to the (small) 12v wire leading to the starter solenoid with key in "start" position. Also, try starting it in N and/or jiggling the shifter in case it's an NSS issue. I would also check the NSS plug where it goes into the harness.

 

he says it turns over, but wont "start"

he says coil pack?

what is NSS?

Thanks,
Randy

 

Neutral safety switch

 

[QUOTE=nickxj94;1782424]Neutral safety switch,

 

thanks, I didnt know that the NSS would allow to crank, but not start, every thing I have dealt with, if was bad, engine wouldnt turn over.

I have always called switches by name, & not abreviations, so I may be slow to catch on what is meant.

also anything like an antitheft that could have been activated accidentally?

I will go look after church today.

it is a RHD version, if that makes any difference?

Thanks again,
Randy

 

Nope, the NSS will cause a lack of cranking. I'm not sure about antitheft on XJs, I thought there was just a red blinky beside the steering wheel? lol

Definitely check for fuel and spark. If you don't have either of these then I believe the Crank Position Sensor can be defective. It's used by the ECU to determine when the engine is spinning fast enough that it can dump some gas and zap in.

 

well it was no spark, tried a coil pack first, thats what he wanted to try, but didnt fix, so he took it back, then got a cps, & stupid auto place gave wrong one & had to go back & get correct one, when we had old one to show to compare.

so yep, another crank position sensor problem, that took a dump at a weird moment.

thats what I thought was strange, it breaking down while being worked on, wondered if something had been triggered? or? oh well, live & learn.

Thanks for all help,
Randy