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6.5 engine

Question: 
5K views 62 replies 13 participants last post by  hockeysticks24 
#1 ·
1996 gmc 4x4 with 6.5 engine
This truck runs great and starts right up when cold. The temp gauge shows about 180 degrees all the time, never runs hot. Runs beautifully. The problem is, after you drive it for awhile and its at normal temp. The truck doesn't want to start. If you wait an hour and let it cool down, it will start right up. Fuel pump is working fine, glow plugs work normal but it doesn't want to start after it warms up. Any suggestions??? Thanks
 
#2 ·
Pour room temp water over the injection pump, after it's been driven, and see if it starts right up. That would indicate a worn IP.
Are you adding any fuel additives? 2stroke oil? howes?
 
#5 ·
What does the two cycle oil do? How much to a tank/gallon?
 
#7 ·
Sometimes, a manual glow plug over ride, so you can make the glows work when hot, will allow it to start hot.
But all this does is delay the inevitable, that the IP is worn.
Most people in this position carry water with them till they change the pump.
 
#8 · (Edited by Moderator)
You can do what the turbo boys did, have a shower head aiming at it. :thumb:

I had to do the water trick with my van for a few months, you get some weird stares I tell you. :hehe:
 
#9 ·
:drinking::drinking:Just tell the people walking by that it's thirsty.:drinking::drinking:
 
#11 ·
There's not much in changing the pump.Pretty much the same principle as the 6.2 diesel.You can expect a few hours work the first time doing it.After that it becomes much quicker.I have a picture to show you in regard to your pump so you can get your timing in the ballpark without getting a stepper motor code.Be back in a few minutes.
 
#12 ·
When you install your pump make sure you centre it within the top elongated slot as pictured here.This will prevent you from getting a stepper motor code.
 

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#13 ·
I haven't removed the old IP pump yet, but your picture doesn't look like the new one I have. This one has the shaft coming out, with a round plate on it. It has a pin sticking out of it about a 5/8" and three threaded holes in the plate which is held on by a large nut. . I can't figure out how you would get the screws in or out of those threaded holes or does just the pin do the turning of the pump. I'll have to wait and see when I remove the old pump and see how it works.
 
#16 ·
Thanks for all the instructions and pictures. I'll start on this when the weather gets better. Too cold and rainy here right now. And, give me time to read all the instructions. Thanks again. I'll let you know if it works or blows up.
 
#17 ·
Can you fill out your location? Thanks.
 
#18 ·
injection pump

Ok, everyone told me because my truck wouldn't start when it is hot, I needed to change the injection pump. It was running great and I took the injection pump off of a "running" truck, Identical to mine. I'm trying to start the truck without the manifold on it. It should start, shouldn't it???
But I get nothing, I've bled every line on the pistons, and I get very little diesel coming out. What am I doing wrong? I know its a good pump, because we ran the truck before I pulled it off. I'm doing something wrong. Will it run without the manifold on it, and if it did How would you time the pump? Every connector is plugged in and its just like it was before, but it will not start. I've bled everything that can be bled but I don't think I'm getting fuel to the cylinders. What am I missing. Thanks
 
#21 ·
Ok, everyone told me because my truck wouldn't start when it is hot, I needed to change the injection pump.
That is simply not true. Everyone here told you to pour lukewarm water over your injection pump the next time it wouldn't start, to SEE if the problem was your injection pump.

Reading this thread, I don't see that you actually performed this test.
 
#19 ·
Make sure the grounds that are at the back of the pass. side head are bolted down.
May be loose with the intake off.
 
#20 ·
I checked all the ground wires, It looks like I have every thing connected and every wire plugged back in. I don't think its pumping fuel to the injectors, I've bled a couple of lines but get nothing out. And, I just pulled the pump off of a good running truck three days ago. I don't have a clue what to do and don't want to burn my starter up. It fit perfect and the timing shouldn't be off but very little if any, it fit right back in the slots easily. Truck was running good with the old IP, just wouldn't start when it got hot.
 
#23 ·
I don't know whats the problem, but I can promise you one thing. If and When I ever get this sucker running again, I'm selling it. I'll go back and find me a truck made back in the 70"s before the age of the computer that controls everything. All I know right now is, this pump ain't pumping any fuel, and it worked great on the truck I just pulled it off of. But, anyway thanks for your advice. I'm going to put my old pump back on and see if that works and sell the thing.
 
#24 · (Edited)
I don't know whats the problem, but I can promise you one thing. If and When I ever get this sucker running again, I'm selling it. I'll go back and find me a truck made back in the 70"s before the age of the computer that controls everything. All I know right now is, this pump ain't pumping any fuel, and it worked great on the truck I just pulled it off of. But, anyway thanks for your advice. I'm going to put my old pump back on and see if that works and sell the thing.
Don't get so discouraged because of something simple. Even with the electronics these are the most simple EFI diesel there is. Going back to old primitive technology isn't going to solve everything, those still break down while getting garbage MPG. I too like simplicity but like I said, for being an EFI diesel, these are very simple.

I would be going over every wire, every injector line etc. Retrace your steps because since it ran before, it has to be something you missed on the install. Does your lift pump work? Did you align the pump gear correctly to the I.P.? How exactly did you bleed the fuel system? PMD harness plugged in with the ground bolted to the top of the I.P.? Injector lines routed correctly? No reason it shouldn't start if the new pump is a quality piece. Crack all the drivers side lines and crank until you see fuel dribble out. But give the starter a rest after 20 second or more cranking. Make sure your batteries are up to the job and it's cranking fast.
 
#25 ·
I numbered everyone of the injector lines when I pulled them off. I labeled every electrical connector and they will only plug into the matching plug anyway. I have grounded every wire that was grounded before. I have fuel going into the IP, but it doesn't pump any out. And it did three days ago on the other truck that was running great. The little bleeder valve in the front, open it up and diesel flows out of it too. I don't know. I'm going to put my old pump back in, it worked great until it got hot and then I'm getting rid of this thing.
 
#26 ·
I numbered everyone of the injector lines when I pulled them off. I labeled every electrical connector and they will only plug into the matching plug anyway. I have grounded every wire that was grounded before. I have fuel going into the IP, but it doesn't pump any out. And it did three days ago on the other truck that was running great. The little bleeder valve in the front, open it up and diesel flows out of it too. I don't know. I'm going to put my old pump back in, it worked great until it got hot and then I'm getting rid of this thing.
Do what you gotta do but this is a simple fix. Did you crack each injector line at least on the drivers side and crank continously for more than 5 seconds?
 
#27 ·
I've even tried shooting starting fuel into the intake manifold holes, all it does is start to knock if you put too much. Something is stopping the pump for pumping fuel, and I don't have a clue why? It has to be something electrically controlled by that stupid computer. It ran just fine with the other IP yesterday, and this IP ran perfect in the other truck. I don't understand the problem but I'm no genius either.
 
#29 ·
I've even tried shooting starting fuel into the intake manifold holes, all it does is start to knock if you put too much. Something is stopping the pump for pumping fuel, and I don't have a clue why? It has to be something electrically controlled by that stupid computer. It ran just fine with the other IP yesterday, and this IP ran perfect in the other truck. I don't understand the problem but I'm no genius either.
Number 1, do not put ether in a diesel or your asking for more problems.

What year is the truck you pulled the pump from? You gotta realize you opened up a fuel system and it needs to work out air bubbles for it to work. This most likely has nothing to do with the computer.
 
#28 ·
I have cracked all four lines on the drivers side, and I may get a little squirt now and then, I work on my diesel tractors all the time, the are pretty simple. There is so freaking many wires an sensors on this thing I don't see how it ever ran in the first place. I just want to get it running again so I can sell the thing.
 
#30 · (Edited)
I have cracked all four lines on the drivers side, and I may get a little squirt now and then, I work on my diesel tractors all the time, the are pretty simple. There is so freaking many wires an sensors on this thing I don't see how it ever ran in the first place. I just want to get it running again so I can sell the thing.
I think you just need a horse and buggy...:whistle: If you think your twenty year old truck is bad, look at the diesels now.
 
#31 ·
The truck I pulled the pump to is just about a Twin to this one, same engine, same pump, every thing is exactly like the old pump. But it doesn't pump any fuel. And I'm going to burn the starter up if I keep on pumping. I can turn the engine over until the oil pressure reaches 50 lbs an that's about 10 seconds, and I get no fuel to the injectors.
 
#32 ·
The truck I pulled the pump to is just about a Twin to this one, same engine, same pump, every thing is exactly like the old pump. But it doesn't pump any fuel. And I'm going to burn the starter up if I keep on pumping. I can turn the engine over until the oil pressure reaches 50 lbs an that's about 10 seconds, and I get no fuel to the injectors.
But is it the same year? If it's a 5068 pump from a 1994, it won't work.
 
#34 · (Edited)
I pulled it from a 1996 truck, just about a twin to this one that was T-boned on the side in the cab, but didn't hurt the engine. It was still running just fine.
Okay so that's not the issue. Really no reason it shouldn't fire. But it needs a solid dribble of fuel from the lines. Did you disconnect the glow plug controller by chance? Look for corrosion on the pump harness.
 
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