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1982 6.2 injector options

well i dont know anymore... yesterday i pulled the mechanical pump and replaced it... got nothing coming from it... so i took it back off again and made sure the pin was pushed all the way up and stuck a little grease on it to hold it back and installed the new pump again... still nothing... so i said the heck with it and bypassed it all together... picked up a fuel pump i got the part number from a forum somewhere that is used on the 6.5 stock... i forgot what year... installed it and now i cant get the truck to run at all... i had a fancy T in it and all that so i could put a gauge but took it all back off cause im still having issued and was thinking maybe one of the joints was leaking... so i ran straight line...

heres a pic of how i did it... i bypassed the mechanical pump all together... both the lines running down to it do nothing now... from the large filter to the pump then straight to the small filter and from there to the injector pump... nice and easy... yet i cant get the truck to run for nothing... i tried everything... unfortunately there is not a lot of info on the internet for the 82 model when it comes to bleeding or trying this or that... dang truck ran till i did this just had the hard start... now i cant get it to run at all...

any ideas?

20140601_130740[1].jpg
 
Its sounds like you have a blockage somewhere. If I understand properly the route goes: tank-large filter-lift pump-small filter-injector pump. Is this correct?

If so: Remove the fuel line from the Injector pump and blow compressed air into the tank at the fuel cap. Don't go crazy with high pressure, you can create new leaks by popping off connections. Try for 20 psi. Make sure you get good flow from the tank to the ip. If you do not work your way backwards until you find the restriction. Keep in mind you can have a plugged pick up inside the tank.

Once you can cause air pressure to push fuel up to the IP, keeping that line off, operate your lift pump to ensure it is pumping the fuel all the way to the IP.

Now to verify the Ip is working and bleed out the air. Crack the injector line nuts free at the injectors. Crank the engine until fuel is coming out, and tighten them one at a time while someone else is cranking the engine. Keep in mind 250-300 rpm cranking speed is needed to start an idi diesel. If you need to hook up a battery charger to do this, disconnect the lead to the glow plugs until you have a good flow to all the injectors. The higher voltage from a battery charger can damage glow plugs.

A different option that works well is leave leave the injector nuts alone. Remove the glow plugs. Crank the engine until a mist of fuel is seen blowing out all of the glow plug holes, then stop cranking. Put in the glow pugs and start normally. This method helps the engine crank much faster expelling any air quicker, and less stress to the batteries.

If you still have problems, a video makes diagnostic way easier.
 
after posting this i finally found a procedure on one of these forums using a air compressor on the IP return line and cracking the large filters OUT port... so i tried this... waited till i got no air... then cracked the OUT on the small filter as well till i got nothing but fuel... truck started!

but my original problem is not fixed now... still a hard start... this method also showed that looking for a leak you just leave everything closed and apply the air pressure... then search everywhere for fuel leaking out... i couldnt find any issues at this point and i already fixed the line under the intake manifold to the IP... so im not finding any leaks anywhere...

When the trucks running and i cut it off then right back on itll start right back up...

if i shut it off and go back 2 minutes later it takes 10+ seconds to start...

leads me to believe there has to be a leak somewhere but i cant seem to find it... do the returns lines also play a roll in this? on the injectors the return lines attached should they have clamps? or any of these small return lines for that matter?

when i took the fuel cap off i still had pressure in the tank? which DOESNT show that i have a leak... so i have no frickin idea lol... at least itll start now... well i guess it will... we will see tomorrow after it sits a full day lol...

thanks for the help man... sorry pretty much killed your time in the last post...
 
The injectors can not have the return lines plugged up or it will cause loss of power , and possible stall the engine. Little spring style hose clamps are needed with one type of hose- if they are leaking when running you need the clamps. Otherwise there are a couple of hose types that fit snug and do not leak. If they leak it will not affect running, just make a big mess and lower mpg to that of a Sherman tank.

The hard start- run the truck then shut off, crack a injector nut and see if you immediately have fuel or not. If you do not have a good check valve in the lift pump the fuel will drain off the IP and you are cranking until the fuel gets there.

Did you install the clear 1/4" return line coming off the IP? That will tell you instantly if you are getting air in the system. I have seen cracked fuel lines that suck air, but did not drip fuel. You can get the same effect at hose connections when the line starts getting hard.

Other question is how long does it run before hard start? hard start when everything is cold in the morning, or only when engine is hot?
 
The injectors can not have the return lines plugged up or it will cause loss of power , and possible stall the engine. Little spring style hose clamps are needed with one type of hose- if they are leaking when running you need the clamps. Otherwise there are a couple of hose types that fit snug and do not leak. If they leak it will not affect running, just make a big mess and lower mpg to that of a Sherman tank.

far as i know nothing is clogged... return lines dont leak or anything just wondering if air getting in would be an issue with drain back...

The hard start- run the truck then shut off, crack a injector nut and see if you immediately have fuel or not. If you do not have a good check valve in the lift pump the fuel will drain off the IP and you are cranking until the fuel gets there.

i will try this in just a minute! although this is what it sounds like to me... me being a jeep guy a hard start is very common because the check valve is in the fuel pump which is in the tank... nobody wants to replace the pump so we just buy a inline check valve and stick it as close as possible to the fuel rail...

Did you install the clear 1/4" return line coming off the IP? That will tell you instantly if you are getting air in the system. I have seen cracked fuel lines that suck air, but did not drip fuel. You can get the same effect at hose connections when the line starts getting hard.

I did not install a clear line no. i have tons of fuel line already and didnt feel like running to lowes to get any at the moment but i probly will... ill just run it between the large filter and new electric pump... from what i read pressurizing the system with a air compressor will force fuel out of these cracks instead of sucking in... but i dont know

Other question is how long does it run before hard start? hard start when everything is cold in the morning, or only when engine is hot?

thats what i was saying above... if i start the truck and shut it off itll start right back up... if i let it sit itll take forever... mornings are the worst...
 
nope no pressure... shut truck off and cracked two lines and nothing from either one... i took a video also and am uploading to youtube now... taking forever...
 
The clear fuel line to watch for bubbles is the return out of the ip. In your video at 25 seconds there is a 1/4" hose out the front of the IP. It starts near the air filter housing, goes under the green wire, and connects to the black metal line that goes from onside of the injector return to the other side of the injectors. Don't waste time with anywhere else, this is where you will see results.

The 1/8" return lins on your injectors are perfect, no clamps needed.

I believe you are loosing fuel prime to the IP. AM General from the factory does just what everyone in Jeep world does-a check valve up at the engine to stop prime loss.

The only other thing that strikes me as odd is the lift pump after the first fuel filter. iirc it is supposed to go tank-lift pump-filters-IP. Even though it is called a lift pump, fuel pumps generate far more pushing pressure than they do sucking vacuum. That is why all mfrs have move their pumps into the tanks, it is simply better to push the fuel.

You need a fuel pressure gauge tied in just before the IP, even temporary to diagnose fuel problems. One that has vacuum as well helps diagnosis better than just pressure, you might think your pump is not working when the system is actually under vacuum boiling of the fuel in the line at a restriction point. I will post a pic of mine asap.
 
I did'int read everything, but the DB2 IPs can just wear out over time. Head & rotor get out of specs and make for hard starts.
I think there is some test you can do?? by hooking a gauge to the IPs transfer pump or something like that ??? don't remember now.
 
Test for hard hot start is to pour water on the IP. If the head and rotor are worn it will start normally as the water cools the IP and changes the clearances.

Sent from my Studio 5.0s using Tapatalk
 
But it is hardest on cold starts. The longer it sits the harder the start. And the hard hot start rules out the glow plugs. Once the fuel supply problem is eliminated compression would be the next to look at.
 
I placed the pump there because it kept it in the same order as the mechanical pump... it may do better elsewhere though... problem is I have hard line all the way to the dual tank switch so it wouldn't be easy anywhere else... it can be done though... there is rubber spot by the AC and Heat blower and I can fit a check valve here easily but a lift pump won't... I'll give that a shot next!
 
Don't say compression lol... it is possible... dude that owned it before me said they guy who owned it before him used ether to start it... I've needed a reason to buy a compression tester anyways I guess... hopefully the check valve does it... I would think pressure between the injector and IP would stay high when shut off...

The motor only has 100,036 miles... old barn farm truck
 
watched video.... rough. have you replaced the fuel filters? while you're adding the check valve, I would pull a slight vacuum on the line from the tank, free-flowing fuel (hence the low vacuum) should indicate the tank screen unplugged. this should give you a solid answer without dropping the tank. next, as mentioned, you're basically looking at compression, injectors and an injector pump. unless the air cleaner assembly is completely plugged. if you do decide to replace the injector pump, don't send it to a shop for a cheap rebuild, absolute waste of time and money. as mentioned again, the head and rotor need replacing, I spent $400 on a "rebuild" and I'm back at square one. better to look for a deal on a new one. used if you're like me (lllllooooowwwwwwww miles of course). nice truck, hope you get it running well.
 
Yes replaced both filters when I did this work yesterday

I hope it's not a IP issue other then bleeding back... it doesn't have a ton of miles on it or nothin... but we will see lol... may be next weekend before I can get a check valve on it to test that... I'll report back regardless of the outcome... found many unfinished threads for these issues lol
 
my experience: 94k little to no ULSD, virtually no use after 2010. the IP and injectors are worn. others claim 100k replacement intervals miles as well. shit, i just grabbed an engine for 2 bills, military, 39k, only trouble is the removal "process" :( booo.
 
huntingman2706217 said:
10-4 sounds good... will do this week... any idea what the fuel dump looking valve on the back is for? Is that standard or a c30 dual tank thing only? Maybe a 82 thing lol... I gotta get in there and work on that passenger side soon too... tanks inop... sending unit acts crazy when flipped too...

I seen the return lines on the injectors piggy backing... they have been replaced and look new... just want to add zip ties or something cause they are just pushed on... maybe that way from the factory but I don't like it... lol

Thanks again man
Click to expand...

My '83 had the drains mounted on the frame right behind the fuel tanks believe it's supposed to be a water drain for the tank, never opened mine and due to Minnesota winters they probably won't budge. As far as the return lines on the injectors if they are the braided style they do not need clamps on them. Good luck!
 
well i swapped the return line with a clear hose... NO air... running or not... also i got to thinking about it and i believe the electronic fuel pump has its own check valve... so i havent installed a inline one... if im not getting air in the return line then more then likely a check valve will do nothing anyways correct?

Im starting to think i need to check compression unless there is anything i forgot to try and should try?
 
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