I have recently picked up this 2002 Ram 1500 quad cab and had the engine rebuilt because it was running rough. 2 weeks later After I’m driving for a bit, the engine starts shaking and feels like it losses compression and dies. It will not start for about 30 minutes and then it starts back up and I can drive for a few miles and it dies again. the longer it sits, the further I can drive. The head shop checked their work on the engine and could find nothing wrong with block or heads. they said the O2 sensors were clogged and replaced those for me. they also looked at the fuel filter and didn’t see anything wrong with it. I needed to know what direction to go from here… Catalytic converter? Battery? Fuel Pump? I took the truck to the Service Dept at a Dodge Dealership… They checked it out and replaced the after-market O2 sensors with Factory O2 sensors and said it was running fine… As soon as We picked it up, it shut off again not 5 miles from the shop… The service advisor tells me that his techs are scratching their heads on what could be the cause of this problem. I’m feeling that the problem lies in the fuel system somewhere, but not feeling confident in the dealer service to find my problem… Any ideas?
crankshaft sensor replace it should fix it. The sensor fails when it heats up, that’s why the longer you wait for it to cool the longer the car runs.
Would that also cause the O2 sensors to get clogged? I had them replaced twice now and worry that some bad gas is in there or my Cat is clogged.
No one should have to guess about either O2 sensors or clogged cats. O2 sensors can be monitored with a scantool and there are at least a couple of ways to check for exhaust restrictions. The most straightforward of these is to just put a vacuum gauge in it.
There is also no need to guess about fuel delivery. You had a shop who said they “looked at the fuel filter and didn’t see anything wrong with it” - ? Whaaaa? I assume that is shorthand for something else. The first thing to know about is the fuel pressure at the rail which you measure with gauge, but it has to have some load put on it. A static test won’t do.
One could learn something about the possibility of a heat soaked crank sensor by starting with the truck when its still running well and heating up the sensor with something like a heat gun. If that gets it to stall then you could also rapidly cool it with some compressed air and see what happens.
Anyway, it is hard to get a shop these days to care enough to do diagnosis, probably partly because people expect it for free, but that’s what you need. I’m not saying its always easy either. If you do have more specific info on what these shops have actually done to check things then reporting that would help.
You may be able to make a little bit of headway yourself. For not much $$ at an auto parts store you could pick up a spark tester and can of starting fluid. The next time it stalls and won’t start hook up the spark tester to check for spark. If you have it forget ignition system related things and move to fuel. Spray some starting fluid into the intake and crank it - if that gets it going, even if for a few seconds then you know its a fuel delivery problem.
The shop is telling me now that it is fuel pump. . The ignition is good and apparently everything tests good at the shop, but dies randomly on the hwy… but when pressing the gas as it is during the stall doesn’t do any good… I told them this morning to check the Crankshaft sensor and even told him about putting heat on it in the shop to see if it causes the fail… this afternoon he said it was the fuel pump. they aren’t really giving me much info when I ask what all they are doing. Just told me that it is running fine when they have it and everything was checking out fine. No more codes have shown up since they cleared the computer before the last stall.
A fuel pump failure should be an easy diagnosis on this car, given that the car is acting up when they have their test equipment on it. I think a local reputable independent shop might be better at this than the dealer because the mechanics there may not be under the same time constraints as the dealer. A failing fuel pump causing an engine to run lean can cause the O2 sensors to read low voltage, which some may mistake as bad O2 sensors. A test drive with a fuel pressure gauge hooked up will easily identify a bad pump.
“Anyway, it is hard to get a shop these days to care enough to do diagnosis, probably partly because people expect it for free, but that’s what you need.”
Not to derail the thread, but “Exactly!” Nothing worth having comes for free. Yeah, I charge you $100 or more for an engine performance/emission failure/check engine light diagnosis, but often times that procedure uses several thousand dollars worth of equipment, service information, and years of experience. It also takes as long as it takes, and if your problem only happens every 2 or 3 days I will keep your car 2 or 3 days to test and confirm. Also if my recommended repair doesn’t fix your complaint I won’t charge you for it. And I do this competing with hacks who say they do the same for free.
You will pay for crank sensor and fuel pump. Which do u want to pay for first?
Bad shops replace parts until fixed$$, good shop diagnose the problem before fixing. Good luck. New crankshaft sensor costs 15 dollars and it is a joke to replace (probably you can replace it). New fuel pump 200-300$$ and there is a lot of labor$$ to pay. So my first option would be to replace the 15 dollar part that requires no labor. Then I will move to the 300$ part. Try the easy stuff first.
Thanks for the help guys… It was definitely the fuel Pump 
Having the work done at the shop this time. I just want my truck back so I can start driving and hauling stuff around again without stalling on the highway full of semis. This group was a big help in getting the right path for me and now that all my vehicles are paid for, I’ll be doing my own repairs to save more money and will be picking your brains again… Val 
@vmfriendly, thanks for reporting back with your resolution to the issue. I would mention that a new fuel filter should go on with that new pump if one isn’t already (and if this is a typical post-pump in-line filter).
I’d also say that if you plan to start doing more work on it yourself, then a repair/service manual is really helpful and important. The aftermarket, off-the-shelf books are usually Haynes and are not very good tough they are better than nothing. But you can find actual factory service manuals online and then other kinds of things in between Haynes and FSM. These things often pay for themselves the first time they make it possible to do a job you would have paid someone else to do.