CUCV crank NO START troubleshooting and questions

[Blastercanon1]

I have recently had some issues with my M1008 being hard to start, I will go through and explain all the procedures I have gone through to diagnosing my problem thus far and maybe some incite can be given for what to do next.

But first I may as well lay out what my problem started out with in the first place, because maybe others have had this problem and so others can go along if they are having the same issue so I will try my best to describe in detail. It gets decently cold where I live and usually I do not drive the truck in the winter as the road salt and wanting to keep this old gal looking as best as I can for as long as I can, and back to the point of where I live it being cold is that I had absolutely no problem starting the truck at temperatures close to 0 degrees with out the truck being plugged in. This year it has had a slow decline ever since it got cold where it has been a little more grouchy every time I go to start it but it would inevitably start, but as stated before it did not do this last winter and it has seemed to take longer and longer each time I have gone to start it. This was on a slow decline until last week it decided to not start at all, I noticed that there was no smoke coming from the tailpipe while cranking so I figured I would start with the fuel system as it appeared that I was not getting fuel. Side not for this is that the truck always smoked for a while until she warmed up all the way so to me its weird that all of a sudden there would be no smoke at all.

So to start with the fuel system here are the thing I checked thus far.
Fuel Filter
I replaced the fuel filter as I have ran around with a spare just in case and what not but I replaced the filter and bled the air from the system and then It still appeared to have e same cranking on and on with no smoke.
Fuel filter Housing
I have read on here that there is a common fail point for the fuel filter housing pertaining to a sensor that is on the Military Stanadyne box filter housing so I Once again took the filter off and it had appeared that someone before me had already to already removed and plugged the sensor hole and it appeared dry and I had figured I would rule that out for now.
Fuel Lines
Next I got under the truck to do a visual inspection of all the lines to see if there were any damp lines or loose connections where I could be leaking fuel or possibly sucking air into the fuel system, I found a couple spot where it was damp but nothing appeared to be dripping. My two areas of concern were the mechanical fuel pump on the passenger front side of the engine block and the sending unit connecting line where the hardlines appear to connect.
Mechanical fuel pump
So I figured since it was very damp around the fuel pump I figured that I would start by taking the line from the pump itself and disconnect the line going to the filter housing and put a fuel pressure gauge on it and give it a test. To the best of my knowledge these should operate around 5-8psi while the engine is turning over. Here is one of my questions that may have me back tracking a little on my troubleshooting, so The gauge reads but the needle is very erratic and using the full range of motion from 0psi mark to the 8 psi mark. I know since these pump are cam shaft driven that they will have some purging as the diaphragm moves but should it move this much or should it be holding pressure as long as I have the tester blocking the supply line out of the pump that goes into the fuel filter housing. I wrote it off as a good pump as I was getting to the desired pressure even though the needle would return to zero almost immediately and maybe it was just vacuum being puled from the diaphragm moving back down but this seemed a little bit more than I was expecting. If this does not sound right then please let me know I would really appreciate it.
Sending unit
Next since it appeared that was my other damp spot I decided to poke around there and since I had just filed the truck up the weekend before I did not want to deal with dropping a full tank of fuel so I opted for taking the bed off which took about 20 minutes for bed bolt removal and lifting the bed off from the help of a backhoe. The lines on the top of the tank did not look great by any means so I decided to replace them. I also removed the sending unit and the sock on the sending unit appeared to be fairly clogged up so I figured what the heck may as well replace the whole sending unit but the closest one had to be shipped in over night and from what I found I had to have a diesel one because of the float and the difference in diesel and gasoline in relation to fuel level reading but anyways that would get there until the next morning so I put everything back together. This included replacing the short shot fuel lines from the sending unit to the hard lines. Bled the entire system and the thing would still not start so I assumed that it wasn't the fuel lines I replaced but then I buttoned everything back up the next morning with the new sending unit. I then let it sit in the heated shop overnight and in the morning it did appear to smoke a little more like it used to so I know there was at least some fuel getting in but still no start, so even though this was not the main problem I thought it may have been contributing
Injection system
This is where my knowledge about runs out as far as how a cucv fuel system works, I have messed with old diesel tractors and dozers so that helped a lot but I am unfamiliar with this injection pump. So I did the basics of taking the lines off of the injectors and seeing if fuel was even coming out while we were bleeding air from the system and it only really appeared to weap out of the injector lines which to me was a little alarming as far as my experience goes. So I assumed that was not enough fuel pressure to acuate an injector so I put a clear hose on the IP to the return line to see if there were any bubbles in the system and sure enough there was but we appeared to bleed them all out after a lot of cranking and a lot of time letting the starter take plenty of brakes in between. There appeared to be some buildup in the injector lines that was inevitably flushed out but seemed like a strange thing that I noticed and may be important for diagnosis. So I le the truck sit over night to see if it was bleeding fuel prime off and the return line had no bubbles in it the next morning but still no starting.

I have not in fact gone and done any testing for the glow plugs or digging any deeper into if my injection pump is doing okay or that's what wrong with it as I have no idea where to start or if I can break into that pump without damaging it. there are a few things I have thought up about what I should check next including,

Glow plug systems
Injector spray patterns and checking for possibly clogged injectors
IP(Injection Pump) timing
Mechanical fuel pump ( If directed to do a test again to ensure it is working properly
Compression (Not sure what my compression rates should look like or if I have worn the engine out)

Anything else you guys think I should check or if you spot something I may have missed while trouble shooting what I have please let me know because I am willing to get my hands dirty and figure this out even though I may not be an expert. Thank you and sorry for my ramblings and possible over explanation

 

[WWRD99]

So first off....this has to be one of the best written questions I have ever seen on any online forum. You have done so much already and answered most questions. You have gotten the fuel issues figured out with the filter housing. The water sensor is usually what leaks but can be fixed with a simple o ring. That's what they removed. I do the heater o ring as well when I do one up. One thing I do getting air out of the system at the injector is only crack a few at a time. That seems to help with the low volume the lift pumps have. The clear fuel line on the ip is a great add. Can look at it and know you don't have air. One thing with that line is, you don't know if you have fuel volume. I think that's what you need and that's the lift pump. It should hold pressure if you have hooked to the hard line side. It shouldn't go to 0 to 8 up and down. You can put a longer hose into a bottle off the ip and see if fuel comes out strong. That would solidify it. Could be a trickle. The next step is to replace the glow plugs...especially if you haven't in the last 2 years. Check voltage at the relay output and see that it is 12 volts and not much higher if you have the resistor hooked up still. Check the big wire on the bottom of the relay that should be the output with the relay turned on. Being it was a gradual slow start I'd go with both. Not a hard job considering all the other stuff you have already done. As far as glow plugs there is the 13g that will fit the stock connectors easy but are getting more difficult to find. The diesel DRX00070 is a great stock replacement and can be found pretty easy. If you have the large connectors the 60g is the replacement. How to tell...the stock connectors are either thin black or gray...anything else like crimp connectors is usually the large 60g size. You might be able to read the old glow plugs and see what was in there too.
As far as fuel pumps I have bought many from this guy on ebay, old NOS ones that have worked for years. Yes crazy cheap too. I have 3 in the cabinet for the ones I haven't changed yet. It takes 2 of us about 20 minutes to change one....my son up top starting the bolts and me down below holding the pump in place. I assume you know to pull the cover and grease the fuel pump shaft to hold it in place. Install the plate, then loosely install the pump bolts and install the steel line first before you tighten everything at once.
So recap, I would test fuel volume and voltage at the relay and go from there. These don't like to start without glows even when hot.

 

[Blastercanon1]

I really appreciate the compliment about the post being written up so well, I really tried to be thorough and be as specific as I possibly could if not to help with the diagnosis and guidance to finding the solution but also to help any others who may be experiencing or going to experience this problem in the future and sort of pass it along to the next guy that needs it. I was very relieved to find that the heavy lifting with the filter housing was already taken care of because it appears they have become very scarce even sourcing a used one off a civi 6.2. You could probably tell when reading my post that even I had my doubts about the mechanical lift/fuel pump being completely checked off my list because I've never really had to test one before because on my older gasoline pickups I always either had the diaphragm give out completely or it starts leaking real bad in between the crimp seal is on the pump and it makes a big puddle. Being that it is a diesel and its not the only fuel pump I figured its a necessity to check with it supplying the IP and that is a part that would rest heavy on my wallet if I overlooked it even if it had not failed all the way and was just starting to wear out I want to get ahead of any issues before they are presented in such a dramatic way like the IP burning itself up. I am thinking that I will be able to get to the Glow plugs hopefully sometime this week and from the sounds of it I may have to remove the injector to retrieve any pieces of glow plug if they broke inside the pre detonation chamber next to the injector, I was thinking I would do a compression test while the injectors are out and possibly watch the injectors to make sure they have a good spray pattern as the truck did smoke a lot before this happened and maybe its more so glow plugs considering the problem I am currently facing. It might be important to add that while it was warming up one side did always smoke more than the other so this may point to the isolation of which bank is acting up weather it is a leaking injector or one side of my glow plug banks is malfunctioning over the other. I am not sure if that has anything to do with it as far as a symptom of that or something else at this point but it could go either way. A little trick I was taught by my grandfather who used to work in a few shops including the GM dealership in the 70s and 80s was when they used to change them they would pack the hole with grease and that would help lubricate the shaft and also hold the pump in place and eventually the grease would eventually break down and assured me that engine damage would not occur from all the extra grease in there. That being said it still does not make the pump being in the position that it is any more convenient. One thing I was thinking was possibly plug the block heater in and see if I get any difference as it is almost hard freezing every night now and the truck is cold after park it for very little time and see if that makes an improvement and then chase the problem in which ever direction it leads me weather it start easier or starts at all i guess. better than I had it running well consistently in the summer.

 

[Mullaney]

I really appreciate the compliment about the post being written up so well, I really tried to be thorough and be as specific as I possibly could if not to help with the diagnosis and guidance to finding the solution but also to help any others who may be experiencing or going to experience this problem in the future and sort of pass it along to the next guy that needs it. I was very relieved to find that the heavy lifting with the filter housing was already taken care of because it appears they have become very scarce even sourcing a used one off a civi 6.2. You could probably tell when reading my post that even I had my doubts about the mechanical lift/fuel pump being completely checked off my list because I've never really had to test one before because on my older gasoline pickups I always either had the diaphragm give out completely or it starts leaking real bad in between the crimp seal is on the pump and it makes a big puddle. Being that it is a diesel and its not the only fuel pump I figured its a necessity to check with it supplying the IP and that is a part that would rest heavy on my wallet if I overlooked it even if it had not failed all the way and was just starting to wear out I want to get ahead of any issues before they are presented in such a dramatic way like the IP burning itself up. I am thinking that I will be able to get to the Glow plugs hopefully sometime this week and from the sounds of it I may have to remove the injector to retrieve any pieces of glow plug if they broke inside the pre detonation chamber next to the injector, I was thinking I would do a compression test while the injectors are out and possibly watch the injectors to make sure they have a good spray pattern as the truck did smoke a lot before this happened and maybe its more so glow plugs considering the problem I am currently facing. It might be important to add that while it was warming up one side did always smoke more than the other so this may point to the isolation of which bank is acting up weather it is a leaking injector or one side of my glow plug banks is malfunctioning over the other. I am not sure if that has anything to do with it as far as a symptom of that or something else at this point but it could go either way. A little trick I was taught by my grandfather who used to work in a few shops including the GM dealership in the 70s and 80s was when they used to change them they would pack the hole with grease and that would help lubricate the shaft and also hold the pump in place and eventually the grease would eventually break down and assured me that engine damage would not occur from all the extra grease in there. That being said it still does not make the pump being in the position that it is any more convenient. One thing I was thinking was possibly plug the block heater in and see if I get any difference as it is almost hard freezing every night now and the truck is cold after park it for very little time and see if that makes an improvement and then chase the problem in which ever direction it leads me weather it start easier or starts at all i guess. better than I had it running well consistently in the summer.

.
Sounds to me like the fuel pump (lift pump) as well detailed by @WWRD99 .
Yep, that trick with the grease on the pushing rod will help installation A LOT.

Just don't forget that testing the lift pump is worth your time.
Rather than pointing the parts cannon at it...

Repeating what was said before, well written post. (both of them!)

 

[WWRD99]

I really appreciate the compliment about the post being written up so well, I really tried to be thorough and be as specific as I possibly could if not to help with the diagnosis and guidance to finding the solution but also to help any others who may be experiencing or going to experience this problem in the future and sort of pass it along to the next guy that needs it. I was very relieved to find that the heavy lifting with the filter housing was already taken care of because it appears they have become very scarce even sourcing a used one off a civi 6.2. You could probably tell when reading my post that even I had my doubts about the mechanical lift/fuel pump being completely checked off my list because I've never really had to test one before because on my older gasoline pickups I always either had the diaphragm give out completely or it starts leaking real bad in between the crimp seal is on the pump and it makes a big puddle. Being that it is a diesel and its not the only fuel pump I figured its a necessity to check with it supplying the IP and that is a part that would rest heavy on my wallet if I overlooked it even if it had not failed all the way and was just starting to wear out I want to get ahead of any issues before they are presented in such a dramatic way like the IP burning itself up. I am thinking that I will be able to get to the Glow plugs hopefully sometime this week and from the sounds of it I may have to remove the injector to retrieve any pieces of glow plug if they broke inside the pre detonation chamber next to the injector, I was thinking I would do a compression test while the injectors are out and possibly watch the injectors to make sure they have a good spray pattern as the truck did smoke a lot before this happened and maybe its more so glow plugs considering the problem I am currently facing. It might be important to add that while it was warming up one side did always smoke more than the other so this may point to the isolation of which bank is acting up weather it is a leaking injector or one side of my glow plug banks is malfunctioning over the other. I am not sure if that has anything to do with it as far as a symptom of that or something else at this point but it could go either way. A little trick I was taught by my grandfather who used to work in a few shops including the GM dealership in the 70s and 80s was when they used to change them they would pack the hole with grease and that would help lubricate the shaft and also hold the pump in place and eventually the grease would eventually break down and assured me that engine damage would not occur from all the extra grease in there. That being said it still does not make the pump being in the position that it is any more convenient. One thing I was thinking was possibly plug the block heater in and see if I get any difference as it is almost hard freezing every night now and the truck is cold after park it for very little time and see if that makes an improvement and then chase the problem in which ever direction it leads me weather it start easier or starts at all i guess. better than I had it running well consistently in the summer.

Having the truck smoke when warming up really points to the glow plugs on that bank are ded. These trucks really do not like to start without glow plugs even warmed up after sitting a short time. I wouldn't go through the testing of injectors and such yet. Smoking doesn't mean to much fuel from a bad injector but a bad glow plug not getting the fuel to fire when cold. The compression test is done through the glow plug hole anyhow. The block heater might help some but the most it will do is decrease the amount of time the glow plugs pre run before the light goes out....which if glow plugs are bad, it won't really change anything. I have mine plugged in, it does start super easy and it is nice having heat pretty quick but that's the main advantage of plugging in though. Getting the glow plugs out is a hit and miss. Sometimes just spinning them and spraying carb cleaner into the threads, with the straw attached, knocks the carbon off the end and it comes out. Obviously it needs to be turned out past the threads to get that part to work. If the steel end has bulged out then it can take more work to get out but spend time spinning the glow plug by hand trying to get it out. What I am getting at is don't ramajammit prybar come out now. That will only cost you a lot more time. If you end up needing the tool to press it out, again, take it slow and try not to break the end off. Sometimes you can stretch it out before it breaks and come out. If it does not really a big deal as removing the injector isn't that tough and a pen magnet gets it out of the precup. The return lines might need replaced since those little clamps like to turn into dust when touched. If you have an advanced auto parts out your way they sell precut lines and clamps made out of viton. Pretty slick stuff and works. If you can get help doing the lift pump I would highly advise it. Even if the other person just holds the pump in place from underneath for 2 minutes while you pop in the bolts from up top would make you not have to look for tools that got chucked across the yard. I use an old sleeping bag to lay on the engine so I don't get gutted by the hood latch. If not removing the passenger side alternator will make it easier by yourself but still sucks. I do glue the gasket to the new pump the day before just so it doesn't move when installing as well. Side note on turning these engines over a bunch, is to make sure you have the front bracket bolted tight to the block and the starter and the starter bolts are tight....verified not looking. Charge the batteries all the time while this process is going too. Don't want any amp ups and voltage drops as that creates all kinds of smoke!

 

[Blastercanon1]

Having the truck smoke when warming up really points to the glow plugs on that bank are ded. These trucks really do not like to start without glow plugs even warmed up after sitting a short time. I wouldn't go through the testing of injectors and such yet. Smoking doesn't mean to much fuel from a bad injector but a bad glow plug not getting the fuel to fire when cold. The compression test is done through the glow plug hole anyhow. The block heater might help some but the most it will do is decrease the amount of time the glow plugs pre run before the light goes out....which if glow plugs are bad, it won't really change anything. I have mine plugged in, it does start super easy and it is nice having heat pretty quick but that's the main advantage of plugging in though. Getting the glow plugs out is a hit and miss. Sometimes just spinning them and spraying carb cleaner into the threads, with the straw attached, knocks the carbon off the end and it comes out. Obviously it needs to be turned out past the threads to get that part to work. If the steel end has bulged out then it can take more work to get out but spend time spinning the glow plug by hand trying to get it out. What I am getting at is don't ramajammit prybar come out now. That will only cost you a lot more time. If you end up needing the tool to press it out, again, take it slow and try not to break the end off. Sometimes you can stretch it out before it breaks and come out. If it does not really a big deal as removing the injector isn't that tough and a pen magnet gets it out of the precup. The return lines might need replaced since those little clamps like to turn into dust when touched. If you have an advanced auto parts out your way they sell precut lines and clamps made out of viton. Pretty slick stuff and works. If you can get help doing the lift pump I would highly advise it. Even if the other person just holds the pump in place from underneath for 2 minutes while you pop in the bolts from up top would make you not have to look for tools that got chucked across the yard. I use an old sleeping bag to lay on the engine so I don't get gutted by the hood latch. If not removing the passenger side alternator will make it easier by yourself but still sucks. I do glue the gasket to the new pump the day before just so it doesn't move when installing as well. Side note on turning these engines over a bunch, is to make sure you have the front bracket bolted tight to the block and the starter and the starter bolts are tight....verified not looking. Charge the batteries all the time while this process is going too. Don't want any amp ups and voltage drops as that creates all kinds of smoke!

Okay good to know I do not know if I want to replace the lift pump and then try and fire it up before I do the glow plugs because from what it sounds like there are diffidently some that are toast at this point from what it sounds like, but if I had to put money on it I would say that it has a failing lift pump and the glow plugs are what is causing it not to fire. That's nice to know that the compression tester would thread into the glow plug hole so I may as well test each cylinder as I go along I figure just out of pure curiosity, but ill have to find the specs for what these cylinders are supposed to run at. I forgot that the glow plugs read off of the temp sensor to regulate how long they stay on I assume as the glow plugs really do not cycle at all or for as long as they do after I did run the engine for while, this is also the reason why I do not think its my relay or my controller card... at this moment in time, talk about an expensive part, so with that in mind I think that as much fun as it would be to go through and only replace the bad ones I think that they all might be on their last leg as far a function ability goes. With the glow plug removal I have seen a tool on ebay that may help with the removal of the glow plugs, do you have any experience in using the "Glow Plug Removal Tool" I can not remember the exact name for it or who makes them but it looks like it goes around the glow plug and plus it out like a traditional puller(kind of) at least that is what i can infer from just looking at it I may be completely wrong. I was noticing that some of my lines underneath were starting to become a little dry rotted including the vacuum lines that I assume go to that sensor or what not on the injection pump and I am not sure exactly what it does but my guess was that it is for the elevated idle but my guess could be completely wrong that is just my guess. That is besides the point but also thought maybe that had something to do with it not starting but not enough to be the main problem if it was in fact the "high idle" or something to do with that nature. I like that idea of gluing the gasket onto the pump the night before as I know I have cussed up a storm trying to get those little b*sterds to stay in place on the gasoline vehicles. I have known people and heard many horror stories about people shearing off the starter bolts and having to put a helix coil in the block down there and I have checked them right after I put the bed back on as I was down there anyways but I have tried to be religious about keeping those batteries alive as they are the big ones that the military would put in them and I would like to keep it as original appearing as I possibly can and I do not know the first second or third place I would even try looking for those batteries once they go bad but I need to put those on the charger for sure as they have been put to work this last weekend and killing them is the last thing I want, I do not want to add two batteries and a 24volt starter to the mix of parts I need to replace at this point.

 

[deank]

I have experienced the swollen glow plugs. When I had swollen one in hummers on active duty and on my M1031, my removal tool was a wrench that just fit over the threads of the glow plug so I could apply outward pressure on the glowplug while backing out the plug by threading it out. Once the threadcutting was well started I would use needlenose visegrips to back the plug all the way out. I have fortunately never experienced breaking one off.

 

[Barrman]

Mechanical lift pump psi testing. I have a gauge on my M715. Between the metal hard line above the passenger valve cover and the fuel filter. It bounces between 5-8 psi with the engine running. But, never below 4. I just walked out and looked at the mechanical gauge and it reads 5 psi and I haven’t started the engine in almost 2 weeks. The psi should hold unless there is a leak at one end or the other is my experience and point.

Wet spots on fuel hose. Air molecules are smaller than diesel liquid molecules. If you see wet spots on the outside of the hose. That means air can get sucked into the hose. Such a leak will keep running your IP dry unless you replace the hoses.

Wet lift pump. I have had 2 with the exact same wet pumps the last few months. I replaced 1 a few weeks ago. It was pumping fuel out the weep hole. The other truck actually left a little puddle on the ground when it was hot out. Now that we are below 40° it is dry as a bone and no puddle. I will replace that pump in a few days because I know it will need it.

Hoses with no wet spots. One of my trucks was running great a few years ago. My son brought a girl to the house to meet us and took her for a drive in the truck. They got back and he said it kept turning off and had to be cranked like crazy to get started again. I did just about all the stuff you documented in the original post and finally solved it with the hose from the filter to the IP. It was old and cracked enough to let air in when bouncing down the road. My point is check everything and if a hose is more than 5 years old. Replacing it might be a good idea. Even if it isn’t your problem today. By the way, she ended up marrying him and the truck now lives at their house.

 

[Blastercanon1]

I have experienced the swollen glow plugs. When I had swollen one in hummers on active duty and on my M1031, my removal tool was a wrench that just fit over the threads of the glow plug so I could apply outward pressure on the glowplug while backing out the plug by threading it out. Once the threadcutting was well started I would use needlenose visegrips to back the plug all the way out. I have fortunately never experienced breaking one off.

That is a really good tip and saves some money as far as the removal process for them, I did not know if the tool was a must have or rather made the job easier. I am really hoping and praying that I do not have to remove any injectors to fish out any broken glow plug bits and pieces. Still might order the tool or give it a shot at removing them the way you explained in your post above.

Mechanical lift pump psi testing. I have a gauge on my M715. Between the metal hard line above the passenger valve cover and the fuel filter. It bounces between 5-8 psi with the engine running. But, never below 4. I just walked out and looked at the mechanical gauge and it reads 5 psi and I haven’t started the engine in almost 2 weeks. The psi should hold unless there is a leak at one end or the other is my experience and point.

Wet spots on fuel hose. Air molecules are smaller than diesel liquid molecules. If you see wet spots on the outside of the hose. That means air can get sucked into the hose. Such a leak will keep running your IP dry unless you replace the hoses.

Wet lift pump. I have had 2 with the exact same wet pumps the last few months. I replaced 1 a few weeks ago. It was pumping fuel out the weep hole. The other truck actually left a little puddle on the ground when it was hot out. Now that we are below 40° it is dry as a bone and no puddle. I will replace that pump in a few days because I know it will need it.

Hoses with no wet spots. One of my trucks was running great a few years ago. My son brought a girl to the house to meet us and took her for a drive in the truck. They got back and he said it kept turning off and had to be cranked like crazy to get started again. I did just about all the stuff you documented in the original post and finally solved it with the hose from the filter to the IP. It was old and cracked enough to let air in when bouncing down the road. My point is check everything and if a hose is more than 5 years old. Replacing it might be a good idea. Even if it isn’t your problem today. By the way, she ended up marrying him and the truck now lives at their house.

I think that I may install an inline pressure gauge just so if I even have the hunch that I am loosing the lift pump again then I do not have to tear apart anything for that sequence of troubleshooting, I also appreciate the incite and help as far as telling me what the the parameters of how everyone else's lift pump are functioning and if it was acting abnormal in accordance to the test I ran.