Been running my 6.9 every day for the past 2 months. Other than sucking air in through the fuel filter and running a little choppy, it started easy and ran great. Last week noticed fuel leak from the fuel tank. Yesterday tried to repair it and made more holes in the process. Had to run out for parts last night with a ton of big holes-fuel pouring all over the place, about 1/2 the tank spilled out. Truck ran great except I got the "ran out of fuel" feeling a few hundred feet from my house-while going up hill (if that matters). Just figured it ran out of fuel, so i added more fuel and ran fine after cracking my injector lines to purge the air. Later last night I patched all the holes with quiksteel in an attempt to stop the leak until my new tank arrives tomorrow. Today the truck starts fine in the morning, runs great for about 10 minutes while i drive to the gas station. I fill up hoping to run the truck hard and get the air out. Leave the gas station and 5 minutes later the truck does the 'heaving' thing again-acting like its out of fuel. Nurse the truck into a parking lot while it idles rough and is starting to slow down on the idle. While idling i cracked the injector caps again to bleed any extra air. No difference. I also checked the oil and saw that within 1,000 miles it went from full to not showing on the dipstick. I added oil, right to the full line. Try to go home-4 miles away, the truck stalled out 4 times on the way home (same feeling each time). After sitting for about 5 minutes, it eventually starts with the pedal floored. It runs like CRAP, but gets farther down the road each time. The IP has been wet for the last 2 months i've been driving it, so i replace it with a new pump from Metro Fuel Injection in Agawam, MA - they're part of Midwest Fuel Injection, great service. After installing new pump and get the truck started, i go for the first test drive. The first 2 miles are good. i stopped and cracked the injector lines to be certain all the air is out. I go to take off and start uphill and the thing has the stalling issue again. I'm able to keep my foot at the same position on the pedal the whole time. It seems the truck wants to die when going uphill but after cresting the hill-it smoothes out a bit. After getting it home, i installed a new fuel filter. Went for a test drive-no difference. After getting it home again, i pulled the fuel sending unit and checked to see if any of the "quicksteel" from the fuel tank patch got clogged in the sending unit. It seemed fine. Now it just plain won't start. i was able to pull the valve stem core from the schrader valve and at cranking speeds - i got about 1/6 of a pint in 10 seconds. Also-the supply/lift pump is about 4 months old-should still be good? But, as it sits now, the injector lines are all a little loose (to see if any fuel is coming out-when fuel comes out i tighten them down). The sending unit is back in the tank. Everything seems to be right and still nada. Only cranks. Doesn't even try to turn over. The new fuel tank comes in tomorrow. The injection pump is new today. Supply pump is 4 months old. Injector o-rings/return lines/caps are 4 months old. My last idea is air intrusion through the tank and time for new injectors. It just doesn't seem right. Went from running great down to a stall and now no-start within one day...something isn't right. Injectors don't just go bad that fast, do they? Sorry for the long post-but had to be fairly thorough

 

have you checked the lift pump on the block?if its bad i owuld look into putting an electric fuel pump on and putting a block off plate in place of the stock one.i dont think your getting enough fuel but i couldnt say for sure.that would be my first idea

 

My thoughts also when I read it. But the lift pump is only 4 months old.
I would check the fuel supply line from the lift pump to the tank for pinholes. Can we assume you only have one tank?

 

Yes-one tank. 19 gallon front tank. it's got holes in it where junk sat in the lip where the top and bottom come together-junk+water sitting = rust. The new 'hole-free' tank comes in today. As far as fuel flow-i left the hard line from the filter to the IP connected. But i pulled the valve core from the schrader valve. I was able to collect about 1/6 pint in 10 seconds of cranking. From the posts i've searched it seems the flow should be 1/3 pint in 10 seconds at idle...perhaps it's about right because it's only cranking and that's like 200 rpm vs. 600 rpm at idle....sound right? Last night i took my batttery out and put it on the charger...truck seems to turn over quick-the same speed it has been the last 2 months. but i read another post a guy recharged his battery and the truck fired-engine wasn't cranking over fast enough to fire i guess. I'll buy another lift pump when the stores open this morning and report back.
Thanks guys so much for the help...tough being 19 and running a business and relying on your truck everyday..but with the help of FTE it's always been minimal downtime- in my '65 and now my '85...thank you!

 

One more thing before i forget. Yesterday I had severe crankcase pressure-enough that it lifted the oil dipstick right off its seal. It lifted it a total of probably 1". Also noticed good amount of smoke coming from the intake and oil fill. I did some reading about a CDR valve-performs similar funcion as a PCV in a gas burner. I will be cleaning that too.
Also yesterday-checked the oil and noticed it was not reading on the dipstick. Seems i did an oil change a month ago-probably 1,000 miles. I read the CDR being clogged would lead to excessive oil burning. Along with that, somewhere i read that low oil levels could effect the engine running? it seems odd that oil would cause fuel problems seeing as they are seperate systems...i don't know much about that.

 

The lift pump flow seemes a bit low, that`s why I suggested you checked the supply pipe to the lift pump. Are you getting fuel out of the injector hard lines while cranking? If not make sure you have 12v to the fuel shutoff solenoid on the injector pump with ign switch on.
The low oil problem is something you can look into when you get it running but the CDR valve is worth checking. However I can`t see it has anything to do with the starting problem.

 

I'm an idiot! truck is good now! after replacing injector o-rings and a return line cap on a leaky injector, the cap was never fully seated. Took a 3/4" deep well socket and a ruber mallet and gently tapped the cap and seated the cap fine. After cranking over a few times-truck fired. Cracked my injector lines to bleed any air and now with the new IP the truck is strong. Let idle for about 10 minutes, shut it off and re-started instantly. I let it run for a minute or so and shut it off. It re-started like so about 4 times. I let it sit for about 10 minutes and again it started instantly. It was hiding in plain sight! I'm still gonna go ahead and clean the CDR valve and install the new fuel tank. I will buy a new lift pump-but not install right away...with all diagnostic procedures; we can't create too many variables all at once...or at least try not. If it does indeed die out at igh RPM's then the new pump will go on, but at any rate i will install the new lift pump in a few days after i know all is well with the new IP. Thank you guys so much for your help!

 

Good man. Glad you got it sorted.

 

you say you had rust and trash in tank i would also check all the lines you may have some trash stuck in it and plugging the lines enough to cause stalling problems until more trash gets to it your lift pump sucks fuel and does not pull enough pressure to pull trash to filter

 

Also are you still using the stock water seperator on the firewall by the brake booster?

Those things are famous for letting air into the fuel supply line.

That could be part of why your lift pump is only pumping 50% of the volume it should be.
Pressure at the schrader valve should be 4 to 6 PSI while cranking.

 

Fuel/Water seperator is out of the mix - Previous Owner bypassed it.

When i performed the Fuel Flow Test the return line cap on one of the injectors was not seated fully. (which was my problem all along - hard way to find out, but will never let it happen again!) I believe since i had air intrusion at the return line cap the fuel flow was 1/2...and the battery had been operating around 60%.

Last night i threw the charger on the battery - brought it back up to 100%. I also fully seated the injector return line cap by gently tapping a deep weel 3/4" socket with a rubber mallet. When used gently the cap just finds it place.

After that i ran the truck this morning and it ran great.
This afternoon the new fuel tank came in so I installed it - at the same time painting the new tank with roof coating paint-especially thick in the grooves on the side of the tank where the junk sits and forms rust!

Right now we have a new fuel tank, new IP, new fuel filter, and fresh fuel. The truck runs great now. With the new IP it runs a bit stronger and definetly puts you back in the seat.
Moral of the story - don't get beat by an air leak!
Thank you guys for your help.