Alright, bare with me as this might be long, but any input that can point me in the right direction or questions answered will help out alot. i use this as my work truck, and i havnt been able to work because i cant rely on it. i need to get it fixed fast so i can go back to work. i have a 2000 dakota with the 4.7, and recently i have been having issues with it starting.

my issue is, when i go to start it, it will just crank and crank but wont fire. Id let it sit for a while then try again. same thing, but usually after the 5th or 6th time it would fire. as the problem went on it got worse and worse and id spend over a half an hour and it would never fire, but when i would let it sit untouched for about 5 or 6 days id go out and it would fire on the first try.

I have replaced the entire fuel pump assembly, air filter, and spark plugs, with no change. I have put a diagnostics on it and it did tell me that i have bad o2 sensors, primarily in bank 1, which im assuming is pre-cat on the drivers side? When i changed out the spark plugs, all 4 that i took out of the drivers side were really bad, really black and cruded up, but the 4 on the passenger werent nearly as bad. Also whenever i get on the throttle pretty hard the truck will bog way down and at times wont even allow the throttle to work and i have to limp it off the road, and then it will give off a "Rotten egg" sulfer kind of smell.

My opinion is that the o2 is bad and causing the cat on the driver side to clog up which would cause the smell, the gunked up plugs, and cause it to run ****ty. but i guess my question is, would a clogged cat on one side cause my firing issue? would it keep the truck from even starting?

thanks for any input.

 

Do you have any codes? Do the key dance. Starting with the key off, key on (not start) off, on, off, then leave on. Any codes will display in the odometer window.

Can a bad 02 sensor cause the plugs to "crud" up? Yes. The PCM would be trying to correct the fuel ratio and is likely going rich on that bank. Change the 02's - don't use Bosch. Hopefully the cat itself is OK.

On the no start, while the fuel pressure "should" be OK with a new pump assembly it never hurts to check it. Put a gauge on the fuel rail. It may be a bad crank or cam sensor too.

 

yea i had a few codes, and one of them was either a cam sensor or a crank shaft sensor, i cant remember, ill have to call the dodge dealership tomorrow when they open and get them to read off my codes that are on my paperwork, they didnt give me a copy. would having either one of those sensors bad cause my cranking but not firing issue?

and hopefully this weekend i can get a gauge and check my fuel pressure to be sure.

 

and i just realized what you said about doing the key dance. i had no idea that you could check your own diagnostics like that, i went and spent $100 this morning to hook the damn thing up to a diagnostics on a dealership. sigh,of course i did, lol. im off to get the new sensor now, and hopefully thats my issue.

 

A bad cam or crank sensor can cause a no start.

 

I agree with 00DakDan.

Please correct me if I am wrong, but I think it goes something like this:
When you turn your key, the starter turns the engine. The cam sensor and the crank position sensor "sense" that the motor is turning and send a signal to the Auto Shut Down relay in the PCM. The ASD relay in turn sends a signal to the ignition coil to start sending electricity to the distributer, sends a signal to the fuel pump to start pumping gas, sends a signal to the oxygen sensor heaters to warm them up.

It was explained to me that this ASD sensor is there in case of a wreck to stop pumping gas once the engine stalls to prevent gas from possibly pouring out on the ground and causing an explosion.

If the cam or crank sensors are bad, they would not send that initial signal (or send it intermittantly) and the ASD would not tell everything to start.

I am new to the Dodge, so please take it easy on me if I am wrong. My 2000 Dakota with a 3.9L was having problems restarting after it stalled and I changed out the Ingition Coil and it appears to have fixed it. But in the process, I did alot of reading and checked and changed most of these sensors.

Also, if you don't already have a fuel pressure gauge, you can get one cheap at Freight harbor. Just make sure that you use thread tape when you hook it up.

 

I forgot to post an update, the issue was indeed the cam sensor, put a new one in and ir fired right up. Thanks for the help guys, it's appreciated.

 

Thanks for the update. I'm glad it's fixed.