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6.5 turbo starting hard and stalling?????

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m38man

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Hello everyone,
I'm new to this site but it seems to be a great place to get some info.
Well to start, I have a 93 2500 chevy with a 6.5 turbo, 175k on it, always ran good but lately it's hard to start and it will stall out of no where. There are no service codes showing up, engine light is not on, just changed the fuel filter, and need to know where to look next, when the truck is running it seems to run fine with good power, but starts with black smoke.

By the way, what does PMD stand for??
thanks
any help is greatly apreaceated
Brian
 
Welcome. When you get a chance fill out your signature line.
PMD= Pump mounted driver. It's the moduel on the side of the injector pump that is a known issue. Tons of threads on it. Do an advanced search. I'll assume by you asking what it is that it means you have not remote mounted it ? If your truck is a 93 I don't believe you have one. The PMD is part of the DS4 Injection pump. A 93 should be a DB2 . Doesn't have PMD or it's realted issues.
Have yo checked the lift pump ?
 
reply

No I havent checked the lift pump, will a bad lift pump cause this problem? what is the best method to test?
should I hear it run when I turn on the key?
thanks again
Brian
 
Hey Brian, thanks for joining the site. Lots of great info and members here. Use the search function and you will be blown away with all the good reading to be had.
 
Open the drain t at the front of the engine. With the engine running it should push fuel out of the drain if it doesn't the engine will die usually after 20-30 seconds. That is about how long it takes to empty your filter manager.
 
Either or both the LP and OPS is/are bad.

If you can still start, do what ak_diesel suggested.
If it does not even start, you need to put 12V source to the LP down on the frame rail approx. under the driver.

If it could start, then OPS is bad.
If it could not start, the LP is bad.
In the 12V source condition, you should be able to measure if there is a voltage on the connector to the LP, if not OPS is bad.
 
After you check the lift pump operation let us know what it was like. Use a cheap vacuum/fuel pump pressure gauge to see what the pressure is out the drain. your lift pump should be on during GP/WTS, cranking and operation. The first two controlled by a large relay on the passenger side firewall, and a fuse nearby. During operation it is run by the Oil Pressure Switch (OPS) which is located drivers side rear of engine behind the valve cover, below the GP relay. The OPS is a common failure item and you should get a new one, get an OPS extension grease hose from PMDcable.com and also change the circuit so that power is provided by a relay triggered by the OPS. There are threads on how to do this.

There are a few other things to check, like your fuel shutoff solenoid, or the cold advance on the IP.
 
thanks

Thanks for the great info everyone, I'll check it this week.
I'll keep you filled in.
 
tried the pump

or ,I tried the valve, when the truck is running, i opened it, no fuel came out, and the truck stalled.
I ran a 12v wire directly to the lift pump, it buzzed kind of loud, but the same happens when i open the valve.
Can the pump be buzzing and not be pumping? Mabe I'll try to crack a line to see if its pumping?
thanks again.
 
Yes just cause it makes noise it doesn't mean it is working. I had one that did exactly this. It may take two people but open the t-valve, put line into a catch can, and jump 12 volts to the pump and see what you get.
 
Usually when the pump gets loud it is going bad.

These motors can sometimes run without it. But mostly not at all.
 
OK,
just changed the lift pump, still the same problem, the pump isn't running at all, I jumped it and still hard to start, where is the oil pressure switch? any way to test to see if it's working? could it be the relay? the fuse is good.
 
Do you get a WTS/GP light? And for how long? And if the LP is not running during that then what conclusion have you drawn......

If the truck starts and is running and the LP is not running, have you checked voltage at the harness? No power to the LP while the truck is running what conclusion have you drawn?

If you jumpered battery power to the LP and it didnt help your issue then you likely have more issues, but you still have to get the LP running.

Look into the glo plug tests, pull some out see if they are wet after cranking.
 
The info is also in my first post for the LP, but for the hard starting have to start looking elsewhere, and Glo Plugs and controllers are notorious
 
m38man said:
OK,
just changed the lift pump, still the same problem, the pump isn't running at all, I jumped it and still hard to start, where is the oil pressure switch? any way to test to see if it's working? could it be the relay? the fuse is good.
Click to expand...

First, read the thread referenced above and also click the link from that thread.
There is a way to jump the LP (overriding the OPS). Try that to see if your new LP is running and the truck can start.
If it does run and can start, then the new LP is good and installed properly. If not, check the direction, LP can only be installed one way.

If everything is good, then OPS is bad.
OPS is close to the firewall slightly toward the driver side of the fuel filter right under the GP controller.

Replace it with ACDelco not other brand.

Also check your battery, it may be running low since you used it to crank when it would not start.
 
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