Another unusual problem. Help please.

[Blacksdieselhp]

My buddy has an 03 3500 auto with 135k on it. It runs good and strong and everything seems fine, then sometimes when you slow down to stop at a stop sign or are just sitting at idle the rpms will drop to about 300-400 and then back up to normal, then a few seconds later it will do it again and evetually go dead. I checked fuel pressure and it is 7-8 psi at idle even when it starts this problem. So does this sound like the CP-3. It does it in gear and in park. He said it has gone dead while going down the road when he lets off the pedal. The injectors get noisy like its running out of fuel. Any ideas. I hate throwing parts at one.

 

[rbattelle]

My guess is a CP-3 problem, possible in the FCA. Just a guess.



-Ryan

 

[Tomeygun]

My guess is a CP-3 problem, possible in the FCA. Just a guess.



-Ryan

I will guess that it is the FCA on the CP3 getting stuck - And now that is a servicable part

 

[Blacksdieselhp]

Thanks. Is there a way to test the CP-3 without putting it on a pump stand? Wheres the cheapest place to get one?

 

[Diesel Power]

Thanks. Is there a way to test the CP-3 without putting it on a pump stand? Wheres the cheapest place to get one?

take it out(fca) and shake it, if it rattles then its good--if not replace it. or it could be the crank sensor among others, a qualified shop should be able to diagnose it with a drb III Oo.

 

[rbattelle]

or it could be the crank sensor among others

Good point, I hadn't thought of that...



-Ryan

 

[Blacksdieselhp]

The DRB showed nothing. Thats why I don't own one. They may make life easier, but in a lot of cases I have delt with, they are useless. Multimeter and test light :-laf . I've embarrassed the tech at the local Dodge place several times with those little tools. But I'm still fairly new on the 3rd gens. So where is the FCA located? If it were a crank sensor, it would throw a code, right? Thanks again for your help.

 

[rbattelle]

The DRB showed nothing. Thats why I don't own one. They may make life easier, but in a lot of cases I have delt with, they are useless. Multimeter and test light :-laf . I've embarrassed the tech at the local Dodge place several times with those little tools. But I'm still fairly new on the 3rd gens. So where is the FCA located? If it were a crank sensor, it would throw a code, right? Thanks again for your help.

It should throw a code if it's the crank sensor, but not necessarily (especially if the condition is intermittent). The FCA is located at the back (toward the firewall) of the CP-3. It's the only part on the CP-3 that has an electrical connector. It looks like a little electric motor.



-Ryan

 

[Diesel Power]

The DRB showed nothing. Thats why I don't own one. They may make life easier, but in a lot of cases I have delt with, they are useless. Multimeter and test light :-laf . I've embarrassed the tech at the local Dodge place several times with those little tools. But I'm still fairly new on the 3rd gens. So where is the FCA located? If it were a crank sensor, it would throw a code, right? Thanks again for your help.

if a sensor fails within its range it will not set a code, thats where expirence comes into play!! Oo.

 

[Blacksdieselhp]

Thats exactly right. On different occasions I have used my own test light and multimeter to show the so called "tech" at the dodge place that a sensor was no doing its job. Everytime he would just scratch his head because he couldn't figure out why his precious $80 machines wdidn't tell him it was bad. Thats the first thing we learned at tech school was never to depend on an expensive machine to tell you everything. In my experience with them, they work maybe 50% of the time.