2001 jeep grand Cherokee won't start
06-11-2017, 06:28 PM
#1
Newbie
Thread Starter
Join Date: Jun 2017
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
2001 jeep grand Cherokee won't start
My 2001 jeep grand Cherokee was running rough, started misfiring and backfiring. Pulled over & shut it off & it will not start. I have replaced crank shaft sensor, ignition coil, fuel pump & filter, cam sensor. I'm at a loss....I have pumped so much money into this thing & still can't figure it out. It will crank over but will not start. HELP ME PLEASE!!!
06-12-2017, 12:01 PM
#2
Old fart with a wrench
Welcome to CF!
First things first. Is this the V8 or I6? Is the check engine light on and are there any stored codes? You can check for codes by turning the key on, off,on,off,then on and waiting. Any stored codes will appear in the odometer. It will say "done" when the sequence is over or there are none. When I say "on", I mean when the warning lights come on.
Did you change these parts yourself or at the suggestion of a "mechanic"?It seems like a lot of parts that may not have been necessary. There are 3 things that should have been checked before throwing parts at it. Do you have fuel pressure? Do you have spark? Do you have power to the injectors?
My best guess is loss of fuel pressure, either by a plugged filter or a failed pump. Because of the way it acted before it died, I think it's a good guess. You can borrow a fuel pressure tester from Autozone or Advance Auto to check. It's got a hose that screws onto the schrader valve (looks like a tire valve) on the fuel rail. The fuel pump runs for about 2 seconds when you turn on the key to charge the rail with fuel. It should show around 50 psi.
The way this system works is when you start to crank it, the computer gets a signal from the crank sensor. Then it turns on the ASD (Auto Shut Down) relay that sends power to the spark coils, fuel injectors, and the fuel pump relay is powered up at the same time. If everything is right, it will start. If the security system is set, it will shut down in about 2 seconds, but it will still start.
You can check if it's got spark by dumping about 2 tablespoons of fuel down the throttle body and seeing if it fires up. If not, chances are you don't have spark OR injector power.
"Shotgunning" of parts can get expensive real quick. A little diagnosis can save a lot of time, money, and heartache. Best case scenario, it could be a broken or chafed wire on the crank sensor harness. On the V8, they've been know to be melted by the exhaust.
First things first. Is this the V8 or I6? Is the check engine light on and are there any stored codes? You can check for codes by turning the key on, off,on,off,then on and waiting. Any stored codes will appear in the odometer. It will say "done" when the sequence is over or there are none. When I say "on", I mean when the warning lights come on.
Did you change these parts yourself or at the suggestion of a "mechanic"?It seems like a lot of parts that may not have been necessary. There are 3 things that should have been checked before throwing parts at it. Do you have fuel pressure? Do you have spark? Do you have power to the injectors?
My best guess is loss of fuel pressure, either by a plugged filter or a failed pump. Because of the way it acted before it died, I think it's a good guess. You can borrow a fuel pressure tester from Autozone or Advance Auto to check. It's got a hose that screws onto the schrader valve (looks like a tire valve) on the fuel rail. The fuel pump runs for about 2 seconds when you turn on the key to charge the rail with fuel. It should show around 50 psi.
The way this system works is when you start to crank it, the computer gets a signal from the crank sensor. Then it turns on the ASD (Auto Shut Down) relay that sends power to the spark coils, fuel injectors, and the fuel pump relay is powered up at the same time. If everything is right, it will start. If the security system is set, it will shut down in about 2 seconds, but it will still start.
You can check if it's got spark by dumping about 2 tablespoons of fuel down the throttle body and seeing if it fires up. If not, chances are you don't have spark OR injector power.
"Shotgunning" of parts can get expensive real quick. A little diagnosis can save a lot of time, money, and heartache. Best case scenario, it could be a broken or chafed wire on the crank sensor harness. On the V8, they've been know to be melted by the exhaust.
06-19-2017, 11:12 PM
#3
Newbie
Thread Starter
Join Date: Jun 2017
Posts: 2
Likes: 0
Received 0 Likes
on
0 Posts
Model: Cherokee
Thanks for the welcome & input Dave! Turns out the cam shaft sensor that was replaced in March was a bad part...it destroyed the distributor. It was around $60 for the fouled part....but I got my $ back 😃 & for the replacement distributor with a cam sensor attached was about the same price. Things are great now!
06-20-2017, 02:45 PM
#4
Old fart with a wrench
This brings up a good point. When it comes to sensors, my advise is to always buy Mopar! The quality of aftermarket sensors is questionable at best. For instance, the Mopar crank sensor uses a neodymium magnet in it's construction where aftermarket ones don't. Yes, you pay more, but in the long run it's money well spent.