94 1500 dies when warm

-
Cope

Cope

Fusing with fire
Joined
Oct 20, 2009
Messages
6,737
Reaction score
10,191
Location
San Jose, Ca.
My 1994 Dodge Ram 1500 is making me crazy. I can not figure it out. About 3 years ago pops took it in for a trans rebuild.

When it was done the shop called and said come pick it up. Some how it was broken and dad PAIED for the trans and brought home a busted truck.

I spent some time trying to figure it out with no luck then I took it to my buddy's shop and He worked on it off and on for a month before giving up. Now Im back screwing with it. @mech1nxh

It fires up fine. Runs and idels fine. Twenty minutes or so and it starts to stumble bad and will eventually die. By playing with the throttle pedal i can nurse it back to the shop but it is not happy.

So. No check engine light, no codes.

Just about all sensors are new. (Im not saying they all work, just that most have been replaced.)

Fuel pressure is good.


I have never been beaten by a vehicle but im starting to fear this may be the first time....

Any ideas or advice would be great! Thank you for your time and advice.
 
Check the distributor. There’s is a piece under the cap that takes a crap. It’s only a few bucks and I’m sorry I don’t know the exact name of that piece.
 
Cope said:
My 1994 Dodge Ram 1500 is making me crazy. I can not figure it out. About 3 years ago pops took it in for a trans rebuild.

When it was done the shop called and said come pick it up. Some how it was broken and dad PAIED for the trans and brought home a busted truck.

I spent some time trying to figure it out with no luck then I took it to my buddy's shop and He worked on it off and on for a month before giving up. Now Im back screwing with it. @mech1nxh

It fires up fine. Runs and idels fine. Twenty minutes or so and it starts to stumble bad and will eventually die. By playing with the throttle pedal i can nurse it back to the shop but it is not happy.

So. No check engine light, no codes.

Just about all sensors are new. (Im not saying they all work, just that most have been replaced.)

Fuel pressure is good.


I have never been beaten by a vehicle but im starting to fear this may be the first time....

Any ideas or advice would be great! Thank you for your time and advice.
Click to expand...


5.7 hemi said:
Check the distributor. There’s is a piece under the cap that takes a crap. It’s only a few bucks and I’m sorry I don’t know the exact name of that piece.
Click to expand...


A guy I used to work with had a Grand Cherokee with a 318 that would not start when warm... For some reason he found that if he kept a spray bottle with water and sprayed the distributor, it would start... He eventually found a problem in the distributor, but I can't remember exactly what it was...

They may not have proppped the engine correctly when they removed the trans to fix it and the distributor hit/leaned on the firewall and screwed something up in there while they had the trans out and the distributor was supporting the weight of the engine....
 
Last edited:
camshaft sensor. whatever you do do not move the distributor. it fires the injectors. it does not have any effect on timing. if you have a jumper box, hook it up to battery and see what happens. if it stays ok, have battery checked. also remove the iac and clean the hole where the iac pintle seats.
 
Battery is new. (3 months)

Idle Air Control is new (yesterday)

Today i removed the throttle body, cleaned it, blew it out and reinstalled it.

The fact that I cant get any codes to register leads me to think the ECM is bad. I pulled the plug on the O2 sensor and fired the engine. The truck ran terrible but the ECM didn't log a code. So... back to the fact the the engine runs like ****, almost all sensors are new and zero codes... I gotta think its a bad ECM?

Thoughts?
 
Cam and crank sensors are bad.
Used to see it all the time in the shop.
Cam sensor is likely the culprit, but if it's gone the crank sensor is right behind it.
Don't buy cheap sensors, they never seem to sync right, one of the things we always made sure was OEM.
 
gunbunny said:
Cam and crank sensors are bad.
Used to see it all the time in the shop.
Cam sensor is likely the culprit, but if it's gone the crank sensor is right behind it.
Don't buy cheap sensors, they never seem to sync right, one of the things we always made sure was OEM.
Click to expand...

What makes you so quick to point at these two sensors?

I know they were replaced by my buddy but Im not saying they are any good.



OBD1 is not as user friendly as I remember from when I was a kid... in fact, it sucks ***. I remember thinking, "WOW, a computer monitors the engine and can tell me exactly what part is going out. That's amazing, This is gonna change the (racing) world!"

Turns out it did, just not as OBD1....
:)
 
Cope said:
What makes you so quick to point at these two sensors?

I know they were replaced by my buddy but Im not saying they are any good.



OBD1 is not as user friendly as I remember from when I was a kid... in fact, it sucks ***. I remember thinking, "WOW, a computer monitors the engine and can tell me exactly what part is going out. That's amazing, This is gonna change the (racing) world!"

Turns out it did, just not as OBD1....
:)
Click to expand...
When we 1st saw it, it gave us fits too.
But we had the equipment to watch the pulses from both sensors and they would be just a smidge out.
The crank and cam sensor would lose sync after the cam sensor would get warm.
Once we figured the problem, it was a few weeks later when Chrysler came down with a TSB addressing the same issue.
Chrysler superseded the P/N shortly afterward.
Later, when I went to work at a outside shop, we tried using aftermarket sensors. They worked great at first, but we found they seldom lasted more than a couple thousand miles.
The typical symptoms were:
Truck starts and runs, from cold fine. About 10-20 mins in, the truck will develop almost a miss. It will act as if timing is out or maybe a fuel issue, but scan tools say otherwise. No MIL set.
Truck cools, starts and runs fine, until it starts all over again.
Always with 94-2002 Chrysler 3.9L, 5.2L and 5.9L Gas engines.
Man, I saw this hundreds of times over the years. Happened to my truck twice.
 
My first thought is they pinched some kind of vent line for the EVAP system and therefore it is vac locking the tank.

But the irregular pressure differential I would think would set a check light.

Does it die while idling? And have you run it with the cap off.
Tp sensors can do the same thing as well.
Mine went bad on my 96 and showed itself on a rainy day with the moisture...no idle.
 
MOPAROFFICIAL said:
My first thought is they pinched some kind of vent line for the EVAP system and therefore it is vac locking the tank.

But the irregular pressure differential I would think would set a check light.

Does it die while idling? And have you run it with the cap off.
Tp sensors can do the same thing as well.
Mine went bad on my 96 and showed itself on a rainy day with the moisture...no idle.
Click to expand...

Good points. I will check these tomorrow.
 
@gunbunny

In your opinion, Should I replace the cam and crank sensors before i replace the ECM?

As sad as it is, im just throwing parts at the truck now.
 
An ECM is a hell of a lot more money than those two sensors. I would have replaced the dist. long ago. Trans shop removes trans, allows engine down too far, and damages the dist. against the firewall.
 
ECM 40-100 Bucks.
But i see where you are at with the distributor being likely damaged by the trans shop.
 
Cope said:
@gunbunny

In your opinion, Should I replace the cam and crank sensors before i replace the ECM?

As sad as it is, im just throwing parts at the truck now.
Click to expand...
I feel pretty confident that the cam and crank sensor replacement will resolve your issue.
If the trans was out there is a good chance the spacing was altered on the crank sensor, I always replaced in pairs.
 
Is the spacing something that needs adjusting?

When I replace the sensors do I need to adjust them or do anything to the computer?
 
Last edited:
Cope said:
Is the spacing something that needs adjusting?
Click to expand...
It's possible the bracket got bent or jacked out of place some. You'll never get it bent back right. The new sensor will come with a thick paper spacer on it, don't remove the spacer, just set it down with the spacer in tact.
The crank will take the spacer off.
 
Cope said:
Is the spacing something that needs adjusting?

When I replace the sensors do I need to adjust them or do anything to the computer?
Click to expand...
If you can still nurse it.. maybe a soft fail on the fuel pump or a tp sensor.
Crank sensors tend to just stop working and not come and go.ime
 
gunbunny said:
It's possible the bracket got bent or jacked out of place some. You'll never get it bent back right. The new sensor will come with a thick paper spacer on it, don't remove the spacer, just set it down with the spacer in tact.
The crank will take the spacer off.
Click to expand...
That's pretty cool! Could you not just tap into the sensor and watch it on a scope to see the pulses fade or something?
 
All very good possibilities. I had 1 truck that the ground wire for the fuel pump on the frame was corroded. It would lose continuity when the wire got warm. Kim
 
Cope said:
Battery is new. (3 months)

Idle Air Control is new (yesterday)

Today i removed the throttle body, cleaned it, blew it out and reinstalled it.

The fact that I cant get any codes to register leads me to think the ECM is bad. I pulled the plug on the O2 sensor and fired the engine. The truck ran terrible but the ECM didn't log a code. So... back to the fact the the engine runs like ****, almost all sensors are new and zero codes... I gotta think its a bad ECM?

Thoughts?
Click to expand...
Ecm probably is fine, my 95 was just sitting idle for 10 minutes Last month & died for no reason. But it started up & no code.
 
A kid I worked with at Matt's had a truck very similar and did the same thing after a transmission rebuild. It ended up being some kinda green and white wire that kinda had "everything" in common got pinched and grounded. Took him forever to find it. I remember the wore colors......that's all I got.
 
Check the oil pump drive bushing. When there worn out it causes erratic fuel injector pulse. Just a thought.
 
pishta said:
That's pretty cool! Could you not just tap into the sensor and watch it on a scope to see the pulses fade or something?
Click to expand...
Yep, that's actually how we noticed the difference. It was so minute.
After that, when the problem came in, we threw a cam and crank sensor and that 99% time fixed the issue.
I think the only time we replaced a PCM for that issue was from a truck, we found out later, was an insurance claim from super storm Sandy.
 
You must log in or register to reply here.
-

Back
Top