Oil Pump Problem

[red2rebel]

Recently I bought a Dakota and it has already had two oil pumps replaced by the dealer, ... I myself took the engine down to see if I could find what is wrong with the pump. once I got the pump off I noticed that the gasket that goes between the oil pump and the bottom of the block was missing. I REINSTALLED THE OIL PUMP WITH A GASKET and reinstalled the transmission due to the fact that I had to remove the flywheel and the torque convertor to remove the oil pan. Now that I got the engine and tranny back together I tried to crank it and it wouldn't crank. So I ran a diagnostic scan on it and the computer read fault code for a failed crank sensor. My question ... is there any way to bypass the crank sensor to prevent it from detecting movement via the flywheel ... or should I replace the sensor? I bypassed the sensor on my 88' 383 cubic inch V8 Dakota I built and had no problems with it. Also is there a recall on the oil pumps on these Dakotas? Is it an inherant problem with the 3.9 litre and if so is there a fix for it?
Any help would be greatly appreciated.

 

[TheLoneRanger]

Red2Rebel, I'm not familiar with the Dodge engine, so this is just my thoughts:

Assuming the CPS reads from the flexplate, you may have bumped it out of alignment when you removed/installed the flexplate. The air gap between the CPS and flexplate is critical, and it may not be close enough now to get a signal. Also make sure the electrical connector going to it is clean and tight.

 

[BOBISTHEOILGUY]

I too am not fimalar with the cps sensors on a dodge but I suspect first you are discussing a newer vehicle. These sensors do feed info on the cranks posistion for timing and ignition purposes to the main computer and with feed back sensors from the cam sensors it can determine when to ignite the spark to the plug. Without one or both, the computer can shut down the ignition and not allow the motor to start. All the crank sensors I have seen are ones mounted on the front of the crank by the lower crank pully. Most flex plate sensors where tach pick signal sensors for tachomenters but with the newer technology I guess it can be on the flexplate as well.

There are many things that can cause this code, but lets look at the obvious. look and ensure you did get the flexplate mounted flush. 2nd, if you removed the flex plate, was it possible to reinstall it in a different posistion than what it was, meaning the sensor is now not in the correct location? Of course the obvious comes to mind like posted above, connections to wires. Make sure you didn't pinch the wires from the pickup inbetween any housing you might have re assembled. This would ground out the pickup signal and not let the computer get any feed back pulse telling it when to fire.

The other thing I was interested to know, why is the oil pump being replaced? what problem do you have when you take it in to them that they go to the oil pump? Is the oil pump pressure low?

 

[OneQuartLow]

First off, I haven't worked on the 3.9 but I have worked on a few older technology DC engines. By "won't crank" I assume you mean it cranks forever without firing? I'd certainly check the CPS first. Beyond the code you were working in that area and its failure can cause your symptoms. What year is this Dakota? The CPS signal is almost certainly mandatory. Without, the ECU will shut down spark and the most you'll get is a quick shutdown after starting. Definitely the first place to look.

About the oil pumps, I agree with Bob. What were the reasons for replacing them? If it's low indicated pressure, is indicated accurate? I'd suspect the sender or faulty connection, but this has probably already been considered. Just trying to throw out ideas.

Good luck, and let us know.

David

 

[higney85]

quick question within the post here... is there supposed to be a gasket inbetween the block and oil pump? I thought there wasnt but im a noobie at this