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Stalled Today Wouldn't Restart

4K views 44 replies 2 participants last post by  Sabyre 
#1 ·
2002 4.7 1500, 214k Miles

Not sure what to look for on this. The truck normally would stall out after a few minutes with a loping idle. You could feather it to keep it going. I was thinking it was a sensor Cam, IAC, something like that. Seemed like it (the truck) wasn't sure how to idle. You could always just restart it.

Today however, It stalled while under thottle (gas pedal depressed) going down the road. And would not restart. It would simple turn over and over and over... Nor aparent firing. 10 or so minutes after trying to restart it the battery went dead.

We had it towed (Thank god for AAA) and are awaiting it to be delivered (140 Mile Tow).

What should we look for. What would cause the truck to stall and not restart when it normally would restart with no problems?
 
#3 ·
I pulled the code p0108 manifold absolute pressure/BARO sensor high input.

I got the truck running and it starts right up, has a loping idle though and eventually will stall out, but it starts right back up.

If I give it throttle up to 3-4k RPM it stumbles and pops like its not firing right.

Not sure how I can check the fuel pressure.

Also, while the truck is running, the engine light stays on, as well as the ebrake light, and the abs light flashes off and on.
 
#8 ·
I replaced the MAP sensor and cleared the code. The old sensor was cracked and messed up. It ran great for about 5 minutes. No more idle surging. I thought we had it fixed then it died.


Started it again and got some poping, backfires, and rich exhaust.


Got codes p0320 ignition distributor engine speed, and p1391 intermittent loss of cmp or ckp.


We also replaced the battery.


I feel like we are getting to the point where we are going to keep throwing sensors at it and hoping for the best.


A couple of times when it stalled out the fuel pump stayed running and the tach would bounce all over the place... 3k, 7k, 5k....
 
#13 ·
Just tested again with lights on. From block to the negative terminal of battery, 0.23v while turning the engine over, would not start right away. As it got closer to starting it would slowly drop voltage. As it started (sorta, with help from giving it gas) voltage was still significantly higher than the 0.04 it should be and it ran horribly.

It's like there is a bad connection somewhere, but where?
 
#15 ·
It doesn' happen that way all the time... most of the time it just stalls out. I got thinking these trucks run on open loop and closed loop modes. During engine warm up it is in open loop mode and basically will ignore input from various sensors until operating tempreture is achieved.

This sounds a lot like what the issue is, but I don't know why. It runs great until it gets to operating tempreture, as I understand it open loop mode settings are predefined, once warmed up the PCM starts taking data from various sensors including o2 (which it subjegates til warm up).

The problem is the o2 sensors are brand new so i'm not sure how that is the issue, if the CAT was clogged it seems to me that the exhaust would be restrickted enough so that very little would come out of the tailpipe.

Then, I got thinking perhaps its an electrical issue that im not thinking of. Perhaps under the fuse box? Lastnight before I called it quits you could turn the key to the on position; normally the PCM would prime the fuel (I think for 3 seconds, the whir click) but this time the ASD was continually clicking and the fuel pump continued to pump until the key was turned of.

There could very well be electrical gremlins as the PO swaped out the motor 40k miles ago with a 'Factory rebuilt one' and it looks like he hacked into some of the wiring.

I think i'm going to pull the PCM today and verify that it is the correct one for the truck (Where is a good place to find that information out?) and clean the connectors and check grounds and things.
 
#16 ·
Ran perfect for 12 minutes or so then stalled out... I made a video but its large so I have to convert it first.

No codes up until it stalled. Code: P0320

When it stalled the fuel pump was still running and the injectors sounded like static.
 
#19 ·
Switched the PCM, That wasn't the problem. Exact same result. Run perfect for 12-14 mins then stall. I should also state the stall is direct, almost as if the key was turned off. And then fuel pump is still running while its stalled. Take the key out, put it back in and still the fuel pump runs.

It has to be electrical at this point.

Knowing that it runs perfect until it reaches a certain temperature leads me to wonder exactly what happens when that temperature is achieved. Knowing that answer would point me in the right direction to diagnose.

Any ideas?
 
#20 ·
Also got "C-Codes", AA, AB, AC

AA = PCM messages not received. Refer to the appropriate diagnostic
information.

AB = TCM messages not received. Refer to the appropriate diagnostic
information.

AC = ABS messages not received. Refer to the appropriate diagnostic
information.
 
#21 ·
After reading the service manual I'm wondering if the problem could be the Front Control Module (FCM). As I understand it the module controls a lot of the systems and provides things like power and grounds. I have also read that it can be responsible for 'flakey' acting gauge clusters.
 
#22 ·
Goign out to pull the FCM, I'm thinking the circuit board has a bad solder point and as it heats up, the solder point semi seperates enough to cause problems...

I feel like im trying to find a needle in a haystack, but I feel confident on this one.
 
#23 ·
I can see the FCM causing problems with lighting and even the gauges, but not the stalling issue. The IPM itself would seem a more likely suspect for that. Have you monitored fuel pressure, injector pulse and spark when the truck stalls to see which you seem to be losing?
 
#24 ·
Yeah, no spark, injector pulse is intermiten, fuel pressure is steady.

The PCM knows the truck stalled, but another part of the truck thinks it's still running. In fact last night fuel was coming out the intake becuse there was so much of it and no where else for it to go.

Could this be a bad ignition switch?
 
#26 ·
Replaced ignition switch. Not the problem. Ran for 22 minutes after the switch.

Same issues. Truck thinks it still running, fuel pump and injectors operate.


Also thuroughly cleaned every ground on the exterior. 6 in the engine bay, 1 on the frame, and 1 on the engine. Could not find any other grounds.


Completely out of ideas.
 
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