I have a friend who has an 84 4x4 with a 6.2. He has put alot of new stuff on it to try and get it to work.
injector pump
glow plugs,controller, relays
starter
filters
lift pump
Injectors
He has had it in two different shops they can get it to start (sometimes) and it will run all day never have a problem until you shut it off. once you shut it off it is done. he has over $4500 in this truck. he is so fed up with it that he is selling it to me for $600.
Any ideas what could be the problem? it is a nice looking truck and i would hate to convert it to gas but i (unlike him) don't plan on breaking the bank on it.

What does it do when you try to start it? Assuming all the repairs were done correctly My guess is you have a leak in the fuel supply lines without seeing it . But you need to tell me more about what it is doing. Does it have fuel going to the injection pump put a clear hose on there to see if you have any bubbles in the fuel. You may have a plugged up suction sock in the tank. But if your getting air bubbles in the fuel it will cause that hard or no start problem. Some times you get rust or tanks lining breaking loose in the tank and building up on the suction sock which makes it restrict the flow of fuel when it sits for a while some of the peaces fall off allowing some fuel flow. You also may have a plugged fuel cap it has to let air in. How is the compression? Cam timing OK? How is your fuel return lines are they free and clear? Do the glow plugs still work correctly? Do the glow plugs cycle correctly that is a problem with that year the glow plug controller doesn't work right or fails? If you have any questions I would be glad to answer them.....Simon 6.5 #1

To me it seems unlikely that the sock is plugged or a massive air leak just because you say the truck runs fine once it starts. An air leak large enough to not allow the truck to start would also make the truck run like a piece of junk with rough idle and surging while driving.
I know little about those glow controllers except that they are junk and frequently don't work new out of the box. Set yourself up with a manual glow switch (search and you'll find lots of posts on how to do it). You could also try to start it by putting a hair dryer at the air intake and see if the hot air will get it to start. If it does start then it's most likely the glow controller.
Put a piece of clear hose on the return line coming off the IP anyway which will show you air bubbles and also whether fuel is getting past the IP.

Also don't put more than a few hundred into these engines, I had a running engine installed for $1200 cnd and I may have gotten ripped off. I paid $800 for mine but now when I do see them for sale the're around $400.
Good luc

i was never around it when he was trying to start it. and he is so fed up that he won't even talk about what it was doing. i won't be able to pick the truck up til saturday. i figure the first thing i am going to do is make sure it is getting fuel. then after that is a guess. i figure i will read some other post on here and try and get a gameplan going. i am in no hurry as this truck is just a project. (it was in too good of shape to let it be crushed)

A pin Hole leak can make it start hard I had one do that look for wet spots on the fuel lines also the sending unit and hoses. One other thing i forget to ask how are the batteries?

They are shot! He tried to start it so many times that they will no longer hold a charge. So I will put two new ones in it.
I will check the fuel lines.
I plan making this a fun project and something that I can work on with the kid.

THe truck has 133,000 on it the body is in great shape. He rebuilt the 700r4 less than 1000 miles ago.
I have a 355 and a turbo 400 just sitting in the garage incase it turns out to be a dead diesel.

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compression?

That is first on the agenda to check. What is good compression for this engine?

around 400 psi is good compression. also i learned this today after putting new brushes in my starter and flipping the disk in the solonoid, unless the truck cranks over pretty fast its gonna be a bag and a half to get it to start, even warm.

Thanks for the info. I really appreciate it.

Well finally got it home.
put in two new optima batteries
tried to start it with the help of WD-40 and after about 8 seconds of cranking it started.
It was running a little rough for about 30 seconds and Then it smoothed out
waited 10 mins went back out and it started right up then I waited an hour started the same way nice and smooth running. I will wait til morning to see if it starts.

glow plugs are not working. i don't know if it is the controller or the relay but they are not getting power.
but on a happier note it started after sitting for almost 4 hrs.
my friend who sold it to me is none to happy they tried to start it for 3 days and couldn't get it to start. plus he had it in the shop for over a week and they couldn't start it either.

I'm glad you got it started Sounds like you got your self a great truck!!! That is why I wanted to know where it was HaHa!!

great deal you got there...i would recheck all the work done on it..then check all the rubber hoses in the fuel system..bad fuel lines (dry rotted and cracked)caused many of these trucks to be given up on....change to manual glow control.. i never give up when done right these engines always run and usually problems are simple fixes

I am putting a fifty gallon tank off my old semi in the bed. I plan on putting a spin on filter from the same semi and I plan on making it manual glowplug control too. New fuel lines and new brake lines

I would like to thank you all for the info and advice you have given me.

Most engines I've checked read 380 -420 psig. It depends on whose gauge you're reading. Most important is that they're all even, within 10%. A low cylinder will cause a misfire but won't keep the engine from starting. If it runs good, once someone gets it started, it's probably not a compression problem. I'd look for a fuel leak on the suction side of the system. It sounds like the fuel is draining back to the tank while sitting. This can be very difficult to locate the problem. The IP can have seals that leak when sitting but hold pressure when running. The fuel filter housing is also a likely spot for a leak that allows the fuel to drain back.

Well It sat from a little past 9pm yesterday til 11:45 today. For some reason the glowplugs worked today and it started right away. So I don't know what is wrong with it .

...Chevy electrical gremlins. They'll get you every time.

Lol oh I know hopefully when I hook the manual controller up I won't have to worry about it.

well i have the manual controller hooked up and it works like a dream. never pictured it being that straight forward and easy to hook-up.
now i need tires.
Once again thanks for all the advise would have been very lost without this forum and it's dedicated members.