Have a 2001 24 valve auto trans 25000 miles.

Died on road, towed to shop, checked codes-none. Lift pump not working, put pressure gauge on and 0 psi.  Remove pump and benched test pump inop.Replaced pump, bleed system and have 12 psi started up.

Will run fine, actually very smooth till warms up and then  hunts and stalls.  Can restart and hold throttle but if left to idle will stall.  Let cool down and starts fine and repeats when warmed up.

Has 12 psi to pump when stalls, put clear line to see if air entering pump ok.  Ended up changing VP44 pump, injectors and distribution tubes, changed Tee fitting on return with compression and real brass ferules.

Seems like when it goes to closed loop problem happens.  Checked coolant temp sender when stalls has back probed about .9 v.

Would appreciate any help or suggestion

Thanks in advance

 

Larry

 

 

 

How are you checking for codes? You really need a OBDII scanner to do it right. You could have easily lost the vp with the lift pump failure but like me mine survived a failure. It is unusual for a pump to fail without some sort of code being set. it is possible the new pump was bad out of the box. Bad electronics in it can really show when things warm up. 

 

Not sure what you mean by "closed loop" and the problem starts???

 

Your coolant temp sensor will change voltage as the temp goes up. IIRC cold it should read around 3.5v and operating temp I do not remember.

 

Some more info on the truck would be helpful. You can go to your profile and fill out your signature with basic info and any mods you have done. It will appear on every post just like the one on the bottom of mine.

Live day of the sensors would be more helpful of want data the ECM is seeing.

 

@dripley closed loop is when the ECM considers its warmed up and ready. 

Edited February 21, 20178 yr by Mopar1973Man

6 minutes ago, Mopar1973Man said:

@dripley closed loop is when the ECM considers its warmed up and ready. 

As in electronically?

Since you changed your VP44 has the problem gotten worse or changed in any way.  You could "hot wire" the IP when the engine is warm to see if the problem continues.  This is powering the VP44 from the battery, it will take other wiring and the ECM out of the equation and it will help you determine if you have a bad IP.  If the problem does persist when it is hot wired all things point to a faulty IP.

For all practical purposes symptoms are the same with recon IP.  Truck is stock no mods, replaced Lift pump with stock replacement.

 

Did try the water hose over IP with no change

 

Used OBDII scanner, does it need to a special one?  Also read codes through odo key on 3 times

 

Thanks for the replies

Looking into fuel quality

 

Thx

Larry

 

Edited February 22, 20178 yr by larryc94