1995 Dodge 1500 360 random no start/rough running

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I have been working on my friend's truck here and there for a while now. He called me today and said that the truck crapped out and wouldn't restart..
I went to look at it and had good fuel pressure but no spark.
I gave the engine a reacharound and shook the harness going to the crank position sensor. The truck started right up, but randomly runs rough and still has random no start.
The CPS affects the running of the engine in that either it works or it doesn't, correct? I could see the wiring being faulty, but I can't see it causing a rough running situation. Correct me if I am wrong, please!
He did tell me that he has been running the tank pretty low lately, thanks to Obama, so trash in the fuel filter could be partially to blame for the roughness..
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Your '95 has a cam and crank sensor. The pcm must see the crank sensor to start but will stay running off the cam sensor if the crank sensor fails after the engine is running. The engine will run off the cam sensor but it won't want to idle very will. If you play with the gas to keep it running, it'll sound like the timing is off by about 20 degrees. If it dies, it will not restart till the key is turned completely off and then back on.
You are correct that the sensor will either work or not. The problem is the sensor can go from working to not working every few seconds. Trust me, that can drive a guy nuts trying to find it. Alot of the time, the sensor works fine cold then acts up as it warms up.
Hope that helps
Denny
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Okay, that pretty much explains the symptoms I have seen. The truck won't restart while it is rolling down the street, and the driver is not about to lock the steering by turning the key off while rolling anyway.. :D Both times I have tried to start it from key- off position, it cranked up. The second time it started, then died, then I didn't turn the key all the way off and it wouldn't restart.
I reckon I will R&R the crank position sensor and look for faulty wiring.
Thanks!
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I assume there's no way to test the sensor with a VOM ? I didn't find any obvious breaks in the wiring. Boy, that thing was fun to reach!
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Well, I went ahead and took a chance and purchased a CPS from Advance Auto...
Before I did that, however, I checked the resistance of the coil to make sure that was not the problem.
Compared to removing the sensor, re-installing it was 10 times harder.. however, it has been reinstalled and the truck runs better than i have ever seen/heard it run before.. So, I think that was definitely the problem. Thanks for the advice!
Hopefully someone will have the same problem and stumble upon this thread!
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Yep, they are really fun to get to. Glad it worked out....
Denny
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Well..... as usual, this one has come back already to bite me in the ass.
The guy called my phone at 2am this morning to let me know that the truck crapped out again just like it did the other day... and, of *course*, he didn't blame it on me and wasn't at all mad about it (ha ha ha.. yeah right).. Obviously, it's my fault that the guy had some drinks and went driving at 2am..
This is what I get for helping my friends out! It almost ALWAYS turns out to cost me an eternity of time and some money out of my pocket. (In this case, the guy will probably want to not pay me for installing the sensor that was installed a couple days ago, since he only paid for the sensor so far...)
Any ideas would be great.. I haven't looked at the truck again yet, but I know I will have to.. to keep from being bad-mouthed.
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I was just thinking of something -- the guy has been running the oil way way down in his truck.. I know on one of my Toyotas, if the ECU sees no indication of oil pressure, it will shut off the fuel pump.
Maybe, just maybe, this is happening on his truck? Usually, I check the fluids of any vehicle that I service, but I forgot to check the crankcase oil this time.. I noticed while driving back to his house the other day that the oil light kept coming on at idle.
I mentioned it to him the other day, and he reckoned he was about 2 quarts low... D'OH! Wouldn't surprise me if he still hasn't put oil into the engine.
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Nza wrote:

2 quarts low is a great way to kill an engine. Sounds more like the owner is a few quarts low as well. Tell him that one beer at a bar would pay for the oil he needs.
And yes if the oil pressure drops it will shut down.
--
Steve W.

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Ok, great! He called and I told him to add oil and let me know.. I'm amazed it hasn't destroyed itself yet.
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ok, no change in the no start...
pbbtt
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Nza wrote:

Got a scan tool?
I would look and see what you have for sensor signals. Could be that the harness or connector has failed. Could also be something entirely new.
I had a 360 a couple years ago that was running rough, would buck and act just like a timing problem. Turned out to be a bad O2 sensor that was an intermittent short. You could watch the ECM drop out just a split second before it acted up and the O2 sensor signal would drop to 0 at the same time. Has almost 130K on it so I swapped all of them and the owner is now very happy. He got a good running truck back and picked up 2mpg from what he had been getting. (all three sensors were going downhill)
How is this truck using oil? Burning or leaking? If it's burning it the sensors are probably shot, they don't like oil burning...
--
Steve W.

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no, I don't have a scan tool.. unfortunately. I suspect you are on to the culprit even without checking it.

The truck has 220K+ on it. I don't think it leaks much, but it puts out a nice blue cloud when you first start it.. I went out to look at the truck today and couldn't find anything obvious.... I did fiddle with the connector for the CPS, as well as unplug and re-plug a few different sensors on the engine. I also disconnected the battery and reconnected it after about 30 seconds, thinking that might somehow do something.. The truck fired up and he drove it home.
I think I'm going to pass this one off to someone with a scan tool and quit wasting time on it!
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Nza wrote:

You can get a good deal on a Genisys unit on Ebay these days. I use mine a LOT, as well as the Tech-2 and DRB and a couple others. The investment isn't bad if you want to DIY and expect to work on your own and help friends/others. Make sure the one you get has ALL the cables and cards. The newest ones are great and I plan on replacing my secong generation unit with a new one or a Pegisys.

Sounds like a candidate for the intake pan gasket repair, there is a TSB on that one. Excessive oil burning at start and low vacuum while running.

Same thing on the one I had in the shop. You could pull the ECM fuse and it would start and run fine for a while.

That or grab one of the cheaper tools that allows you to watch real time data and see what the sensors are doing. I have an Actron unit that is my loaner tool and it allows you to do limited testing and see most live data. http://www.actron.com/ (mine is older and no longer listed but the newer ones do MUCH more anyway)
--
Steve W.

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Ok Steve, I think you've shown me the light about having my own scanner..
I *do* expect to get more work from friends... they all drive newer junk with electronics. My daily driver is a '79 Celica, so it either runs or it doesn't... :D
Thanks to everyone! This group is great!
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** UPDATE **
Truck wouldn't start again yesterday. Went over today and sprayed some ether at the front of the intake manifold, and the truck fired right up. It died immediately, so I did it again. It started up again and died. The third time, the truck kept running.
I reckon that proves that it definitely could use an intake gasket set.
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**UPDATE**
Took me a few afternoons to git-r-dun, but I finally replaced the plenum pan gasket on this truck. I got the fel-pro intake gasket set.. Once I pulled the intake and the plenum pan, it was obvious that it was leaking. I believe someone did the job before and failed to scrape all of the gasket material off the plenum pan.
Anyway, once it was all back together and dried for 24 hours, I turned the key and it fired up instantly. We drove around for a while and didn't have any problems.
Thanks for pointing me to the problem! I really think we have it licked this time.
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Stupid truck is still stalling randomly. He says it's running at 500 rpm at idle now with or without the A/C.. The truck always will crank up and go again, now that the gasket has been replaced... but this is pretty annoying. I noticed that the EGR valve is non-functional when I did the manifold gasket..
The check engine light has stayed off..
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On 04/20/2011 09:31 AM, Nza wrote:

My guess is bad fuel pump.
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My problem of rough idle and stall seemed to be the idle motor. When cleaned it the truck ran fine. That gave me slot of trouble years back. Been good lately.
Greg
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