I HAVE A 95 GMC Z-71 WITH A 6.5 TURBO DIESEL . I RECENTLY REPLACED THE PMD WITH A COOLING UNIT TO START . THEN THE OIL PRESSURE SWITCH AND THE LIFT PUMP .CLEANED THE K/N AIR FILTER AND RE-OILED IT . THE TRUCK RAN GREAT AT FIRST(FOR ABOUT AN HOUR TOTAL) BUT WILL NOT RUN ANYMORE . THERE IS FUEL COMING OUT OF THE T HANDLE AND OUT OF THE TOP OF THE FUEL FILTER WHEN I CHECK FOR PRIME . THE MOTOR TURNS OVER GREAT BUT WILL NOT FIRE . I CHECKED FUSES HOSES AND CONNECTIONS RESET THE ECM THROUGH PULLING THE FUSE BUT NOTHING HAPPENS .I CAN HEAR THE LIFT PUMP WORKING ALSO . THE BATTERIES WERE DISCONNECTED WHEN I REPLACED THESE PARTS SO EVERYTHING SHOULD OF BEEN SAFE . IM LOST , I HOPE SOMEONE CAN HELP

 

is fuel coming out of the injectors. is the timing correct, it could of been messed up when you reset the ECM. do you have a techscan to check it. that would be useful. also turn off your caps because it seams like you are screaming

 

crack one of ur injector lines open while you have a buddy crank the engine. If no fuel, it could be that you got a faulty pmd, the extension harness(if relocated out of the engine bay) could be faulty, or your injector pump took a dump.

 

Thank you ill try that . But it makes no sense to me what is going on because it was running fine after I replaced these items and then all of the sudden it wont run . Thank you again for your help and if you have any more suggestions that would be nice .

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Thank you ill try that . But it makes no sense to me what is going on because it was running fine after I replaced these items and then all of the sudden it wont run . Thank you again for your help and if you have any more suggestions that would be nice

 

Did it quit while running? Or just not start up next time? I would probably suspect the pmd the most but not always. Check the shutoff solenoid also. When you turn the key on it should click. After that you will need the intake removed to test any further. I would also check for codes. Could be a bad encoder.

 

It kind of did both . The truck ran fine on last friday but would not start saturday morning . It attempted to start but would not stay running for more than about 10 seconds . Now it wont even attempt to fire . It turns over but wont start . I wonder if the new oil pressure switch that I replaced is faulty because the gauage inside the truck now fluctuates all over the place . Can you tell me where this cut off switch is located ? The truck is throwing codes but my mechanic said that these were basic codes and their nothing that should affect it this severly . Thank you very much for your input !

 

It is under the intake manifold in the valley. Not exactly easy to get to.

 

just loosen 10 or 12 bolts a couple clamps and you have unbolted your intake manifold.

 

I cracked the injector lines and no fuel came out . I swapped out the oil pressure switch with a new one . I popped the sock off the in tank fuel pump by using an air commpressor . Checked the fuel cut off switch that is mounted on top of the injector pump and it works fine . There is fuel getting to the pump but none is coming past that point . I also checked connections to the pmd , they are also fine . So does that only leave the pump? I heard of a optical sensor thats located in the pump itself , they say this part is not servicable . Can you explain what im looking for when i remove the intake manifold ? Also I was offered 1500 dollars for the truck not running , should i take the money or is it worth fixing the truck ? I just wonder if these problems are likely to continue after putting the money into it .

 

it looks like someting is wrong with your injection pump. go to a pump shop to get a recommdation on wither to get a new one or get your present one fixed. when you lift your intake manifold you will see a injection pump with 8 lines coming out of it. optical sensor is not servicable because it is inside pump i think. not 100% posive.

ive never seen your truck so i dont know what type of shape its in so if 1500 dollars is a good deal or not. as far as it runs after a new injection pump, move PMD, and other mainetance items it should run forever as long as nothing is catasrphocially wrong. sorry i cant spell tonite