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Car Forum / Dodge / Dodge Trucks / September 2006

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HELP Starting and Stalling Problem LONG

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Tom - 16 Oct 2003 18:57 GMT
My problem started as a nuisance and progressively worsened into a
disabled vehicle.
I have a 1994 Dodge B2500 Ram Van, 3.9 L, MPFI with 88k.  A few months
ago it would occasionally crank excessively and finally fire up.  I
found this got worse and more frequent.  When cold, the fuel would
take some time to prime  usually about 10 - 20 seconds. Once hot, the
motor would start on the first crank and continue to fire up through
out the day.  The problem only occurred when the engine was cold.

I have since replaced the spark plugs, wires, air cleaner, PCV valve,
breather, distributor cap and rotor, and finally the fuel pump.  I
also tested the operation of the MAP, Crankshaft postion sensor,
Camshaft position sensor, Throttle position sensor, and the Idle Air
control. This did not fix the problem.  It may have created a new one.

Now it takes approximately 2- 10 minutes to prime the fuel.  A
pressure tester shows 40 psi at the fuel rail once primed.  Now,
however the autoshutdown and the fuel pump relays "chatter" for
several minutes.  They toggle on and off very quickly - several times
per second.  While this happens the fuel pressure climbs and when it
reaches 40 psi, the relays stop clicking and the ignition is enabled.
Once the relays stop making noise , the motor turns right over and
fires up easily.  I tried to ground the relay PCM ground wire ( dk
blue with yellow stripe) directly to negative battery terminal. This
forced the fuel pump on,  but would not allow me to start the engine.
I assume this is because although I had fuel pressure, I had no spark.
It would not fire until the jumper was disconnected and the relays
were allowed to continue chattering until they stopped.

The diagnostics show a code 12 - PCM voltage and a 45 overdrive
solenoid.  I finally took it to the dealer who spent a few minute
with it but once the tech realized I had installed an aftermarket
alarm and remote starter, he would not investigate any further.  I
realize the wiring modifications could cause the intermittent power
failure, but they're not new - they've been working fine for four
years.  And if it was the cause why would it only occur when the
engine is cold?  I have checked the wiring connections and all appear
OK.  The dealer said I would have to disconnect the systems before
tehy will analyze any further.  I am willing to do this but in the
meantime, it now stalls,

I've been able to live with the starting issue.  It only takes a few
extra minutes to "prime the pump".  Since this problem only occurs
after teh van sits for a long period of time, I've spent weeks trying
to troubleshoot it!  Once the motor is warm it starts fine.  But
now,perhaps I screwed up something while troubleshooting, the engine
won't accelerate smoothly past idle speed.  If I give it a little gas
it sputters rather violently and then stalls.  If I give it a lot of
gas it sputters and revs past the stalling point and then it runs OK.
(Well I have lost a lot of power now, and I keep the van in the
driveway until I can figure this mess out.)   I have monitored the
voltage coming off the TPS and it consistenly increases from 0.6vdc,
when closed, up to 3.6 when the throttle is open.  Even through the
stalling point. It seems to be vacuum related although vacuum is
steady at 17 in Hg.  I relaize theis may be kind of low.  It was 18 in
Hg when I first started messing with it, but it's been rock steady the
whole time.

I believe  have two separate issues, although they may be related.  I
thought if I spent the money, the dealer five star expert techs would
be able to tell me what the runnablity issue was with stalling above
idle speed.  Unfortunately they won't go past the starting situation.

Why am I stalling?
Tbone - 16 Oct 2003 19:11 GMT
How old is your battery?  It may also need to be replaced.

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If at first you don't succeed,  you're not cut out for skydiving

> My problem started as a nuisance and progressively worsened into a
> disabled vehicle.
[quoted text clipped - 60 lines]
>
> Why am I stalling?
Tom - 16 Oct 2003 22:12 GMT
> How old is your battery?  It may also need to be replaced.

The battery is less than one year old.  Checked the cells OK. Cleaned
all the terminals all the way to the engine block.  I don't think it's
the battery, but I'll try to get a voltage check under load.
sandyk - 19 Oct 2003 16:16 GMT
With the description that you have written, and through everything that you
have looked at, have you looked at the Fuel Injecters?  This doesn't sound
like a vaccuum problem. You may even have to have the fuel rail and the
injectors cleaned. There is a process that takes about a 1/2 hour, and runs
around 70.00
They attach a cleaning bladder to the fuel rail, the engine runs off of
that, and when the bladder is empty, the engine stops and the system is
supposed to be clean..I'd look at that next..Does sound like you have
clogged injectors..

> My problem started as a nuisance and progressively worsened into a
> disabled vehicle.
[quoted text clipped - 60 lines]
>
> Why am I stalling?
frerichs@ro-dot-.com - 20 Oct 2003 05:18 GMT
The fuel pump relay should NOT chatter.  Look at the voltage on both
sides of the relay coil while it is doing this.   Most likely you
either have a rusty ground problem, a rusty connector problem or a bad
computer.   I would look at and clean every ground connection and
power connector to the computer that you can find.  If this cheap fix
don't work then replace the computer.

>My problem started as a nuisance and progressively worsened into a
>disabled vehicle.
[quoted text clipped - 60 lines]
>
>Why am I stalling?
Tom - 21 Oct 2003 20:16 GMT
> The fuel pump relay should NOT chatter.  Look at the voltage on both
> sides of the relay coil while it is doing this.   Most likely you
> either have a rusty ground problem, a rusty connector problem or a bad
> computer.   I would look at and clean every ground connection and
> power connector to the computer that you can find.  If this cheap fix
> don't work then replace the computer.



I cleaned every ground connection I could find.  Through the data
connector from the PCM I found the ground lead, a black and tan wire
which is continuous with ground until I turn the key to the run
position. It then goes infinite (open.) for a while.
If I leave the key switch in run eventually the PCM grounds the
following circuits intermittently:  the ASD Relay, Fuel Pump Relay,
EGR Solenoid, Purge Solenoid.  After a few minutes they start to chirp
or chatter, very fast.  A multimeter (set on continuity) connected
between the PCM ground (Bl/Tn) and the battery -, chirps along with
the clicking of the relays and solenoids.  The ground circuit is
continuous once the clicking stops.  (The motor will always start at
this point.)  I also noticed the check engine light does not
illuminate until this "warmup period" is over.  If it is lit I know I
can start the engine.

During this same period, I measured the voltage coming off the ASD
output and found it starting at millivolts and then ratcheting up,
1.1, 1.3, 1.5, 2.0, 2.02, etc. up to 12 vdc.  When it hits 12 the
engine starts right up.

I also measured a steady 12vdc at the DkBlue wire in the data
connector when ever the key switch is in run or start.  What would
interrupt the PCM ground?  It must be internal to the PCM, or am I
missing something?
kicker42 - 09 Sep 2006 15:48 GMT
Did you ever find  A solution to this? I have the same thing going on with a
ram 3.9 1994 and a dakota 3.9
>> The fuel pump relay should NOT chatter.  Look at the voltage on both
>> sides of the relay coil while it is doing this.   Most likely you
[quoted text clipped - 27 lines]
>interrupt the PCM ground?  It must be internal to the PCM, or am I
>missing something?
 
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