View Full Version : 6.5 trouble shooting
So I have a 95 k1500 that i recently picked up. I believe my pmd went out on me, my truck will run for about 10 minutes then it dies and if i go to idle the truck gets a nasty lope. Any other potential issues I might be missing?
DmaxMaverick
01-03-2020, 21:34
Welcome aboard!
It could be the PMD, but check the lift pump for operation and performance. It should provide steady 4-10 PSI at idle (measure with a gage connected to the fuel filter water drain --the T-valve located at the thermostat housing). Intermittent operation often suggests OPS (Oil Pressure Switch) failure.
Being that it's a 1995 model, you can check lift pump performance without starting, or jumpering anything --- Set E-brake (and/or chock wheels), turn the key to ON, but don't start, move tranny shifter out of P, but not to N, turn key to Start. It should not start, but the lift pump should run as long as the key is held at Start.
The only reason I feel its not the lift pump is because it will start and drive. But just about when it gets to operating temp itll lose all power and die. but it doesnt throw any codes
When it dies, try throwing cold water on the PMD. If it then restarts the PMD is the prime suspect.
If you have a scanner program, sometimes, when the PMD starts to fail, you can observe solenoid closure time start to fluctuate right before the "stall".
I am with Maverick
Check the lift pump with the tranny in drive...ENGINE OFF and hold key in the crank position..
Starter will not (Should not) operate, but the lift pump should.
Make sure there is fuel available at the drain up front.
Stick the hose in a can and operate the lift pump..
You should get a nice flow of fuel.
WHEN was the filter last changed ?????
If the fuel flow is sketchy then the pump is suspect.
Or as Maverick mentioned the oil pressure switch is/has gone south.
With the engine running try opening the fuel drain.....if fuel flows this is good..
If the engine stalls then the lift pump is faulty.
A weird stalling is always a time to suspect the PMD... but due to the $$$$ its good to wring out the other possibilities first...
Check the filter and the lift pump....if no issues found then suspect the PMD.
The IP has a transfer pump inside, and it will pull fuel, but it's not what its meant to do and once things warm up and the engine idles down the transfer pump will/can fail to deliver enough fuel, resulting in a stall. (The lift pump is required to deliver a steady flow of fuel as Maverick mentioned.
A failing PMD will in many cases cause a stall and no restart until it cools...worst case is a stall and no restart at all...
A few years ago I had a similar problem with my 1995 6.5. It would start and run for a while and when I would be driving it the engine would shut down. There were no codes but after 5 or 10 minutes it would restart and be fine for the rest of the day. I did notice that when it would shut down the glow plug lite would not come on. After a while, the glow plug lite would come on and the engine would start again. This went on for a few months and then it would not start at all. After going thru the manual I saw where the glow plug controller has to send a signal to the computer in order to get the engine to run. I changed the glow plug controller the problem went away. After taking the glow plug controller apart, the contacts were in very bad shape.
Well, it's not the PMD. I ordered a new one and installed it today. Same thing happened on my way to work. I will test the lift pump when I get home. But at least now I have an extra PMD if I ever need it.
Is your fuel tank venting correctly?
Yukon6.2
01-11-2020, 10:22
Well, it's not the PMD. I ordered a new one and installed it today. Same thing happened on my way to work. I will test the lift pump when I get home. But at least now I have an extra PMD if I ever need it.
That's good because you will need it.Not if but when!
The PMD is considered "A consumable" with these things..
Like oil and filters, air filters...etc....WELL maybe not that often, but they are an item you should carry in the glove box....and tools to swap it.
More Power
01-13-2020, 11:39
Shuts Off While Driving - Stalling
https://www.thedieselpageforums.com/tdpforum/showthread.php?t=2938
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