2001 jeep cherokee won't start

jeep
cherokee

#1

Engine turns over but will not fire up or sputter. Fuel pump runs and there is fuel pressure at the supply line but I do not smell fuel if the pedal is pumped so I don’t know if it is getting through the injectors. It has a bar which i believe has the coil in it across the spark plugs instead of wires so I’m not sure how to check if it has spark. The auto-shutdown relay seems to be working. The codes that came up before this happened were P0455 and i think, but not sure of P0432. The are gone because i disconnected the battery overnight hoping that would clear the memory and solve the problem. Could it be the crank position sensor and how do i test it? How do i test for spark with the bar? I have some mechanical knowledge but electrical/electronic leaves me at a loss.


#2

If you’re not smelling any gas while cranking the engine over it means the injectors aren’t firing. And in order for the injectors to fire the computer must see a signal from the crankshaft position sensor.

There is no real easy way to test for a bad crank sensor unless you have a scanner that can monitor the crank sensor signal while trying to start the engine.

The crank sensor is mounted on the bell housing flange for the transmission. Crawl under the vehicle drivers side, and look way up. You’ll see it. And when changing the crank sensor, leave it plugged in. Then when it’s unbolted, pull it up through the firewall. Plug in the new sensor and lower it back down the firewall. Now the fun part is mounting it back onto the bell housing flange.

Tester


#3

Thanks for the info and the quick response. It did raise another question for me though. If the computer does not get a signal from the crank sensor, would it also prevent the spark plugs from firing in addition to shutting down the fuel injectors? I sprayed starter fluid into the throttle body and attempted to start it, but it did not. I assume if there was spark it would have run until the fluid burned off. Any other likely possibities besides the crank sensor? That thing is really way in there!


#4

I just replaced the wifes crank sensor on her Jeep for this same problem. Only she had to have it towed to the shop because it left her stranded.

When the injectors don’t fire, it’s the crank sensor.

And that ether you were spraying into the engine? That was firing off from compression. That’s how starting fluid works. And why it’s never used in a diesel engine.

Tester


#5

[b]

Could it be the crank position sensor and how do i test it? How do i test for spark with the bar? I have some mechanical knowledge but electrical/electronic leaves me at a loss. [/b]

My son’s 2000 Sport had a no start with a bad crank sensor. No code when scanned too. The crank sensor fires the ignition. The cam sensor (where your distributor used to be) fires the injectors.