Hi All!


I have a 1999 Suburban with a 6.5L Turbo Diesel. Purchased about three years ago with 80,000 miles, now has 124,000. Truck had a service engine light and stalling that a "so called" local diesel mechanic could not figure out, he said his machine could not communicate with the truck's computer. Sent to dealer and they diagnosed a waste gate problem. That resolved the servce engine light and some black smoke on acceleration but stalling is still present. Dealer gave me some BS line about maybe it was residual carbon build up or bad gas.


I checked the lift pump and I can feel it running when truck is running. The other night I was poking around under the hood with the truck running and I touched the lead going to the waste gate solenoid and the truch stalled, I think this was just a coincidence but I am not sure. From what I have read, would it be the PMD? Could it be the oil pressure switch? What tests shoild I perform? Truck stalls mostly at idle or when comming to a stop but also sometimes when just running at a steady speed. Today it stalled and I knew it was going to happen before it happened, it felt like it lost power as I was slowing down. Any help/comments would be appreciated as my wife is ready to get rid of the vehicle for safety reasons.


I am leaning towards a remote PMD cooler set up and an oil pressure switch saver and replacing the oil pressure switch? Any comments as to these items? Thanks

Any power wire grounding out could cause it to stall.
If the lift pump is running with the engine on then OPS is good .

Check wg solenoid connector and wires for chaffing.
shaking wires with engine running can show where bad connections are.
PMD can cause these problems.

Hearing or feeling the supply pump run means yes its running, but you need to bleed the filter base with the truck idling to see if its actually moving any fuel, a weak lift pump is just as bad as and inop one. If you immediately see fuel squirt when you bleed it then it is OK, if you don't get any fuel then your lift pump is weak and needs to be replaced, if you get air bubbles and then fuel you need to find where the air is coming from, tank pickup most likely. While your there, its a good idea to go ahead and remove the filter and inspect/replace it and inside the base for signs of contamination. Need to find someone who can scan it for you and see what codes come up, no wastegate or carbon buildup problem can make your truck stall. Be sure to check DTCs, Closure Time, Cam/Crank Misses, and make sure all readings from the sensors are with in reason. Good idea to check/replace air filter to as the '99s can be a little squirrely with the MAF sensor.Edited by: Texas Diesel Guy

Fuel squirts when bled at the petcock, no air bubbles. Air filter is K&N and was cleaned recently (probably 5,000 miles ago and no dusty conditions). When dealer had it they hooked it up and no codes were stored. They ran it with their computer hooked up to it for a couple of days and could not get it to repeat the stalling. Three or four days after I got it back it started again. I will recheck filter and base for signs of contamination. Thanks.

Stalling no codes and no other signs of cause for stalling usually means bad driver, not you the PMD ;)

Well, I went back and rechecked both filters (there is a seperate remote fuel filter/water seperator in addition to the regular/primary filter) and the primary filter was not in good shape so I replaced and also drained/inspected housing. No contamination, just a dirty filter.


The next day the stalling saga continued http://www.dieselplace.com/forum/smileys/Cry.gif so I ordered and installed a remote PMD with cooler. The best place I could find to mount it was on the bracket with the ABS module. After driving for about a half hour the heat sink was warm to the touch (but not so warm that I couldn't keep my hand on it) so I guess it is working. I might try to fabricate an air ram to get some additional airflow to the unit while driving. I would think that a fan of some type would also be helpful, any ideas?


I will try to take some pictures of the installed unit this week. I have my fingers crossed, no stalling so far but it is only the first night. http://www.dieselplace.com/forum/smileys/Thumbs Up.gif