chevummins

hey guys... I just reinstalled my bosch ve pump on my '93 D350 and wonder how long it should take to bleed the air out of the system. I cranked on it a bunch and it is still spuing frothy air at the injectors. I have bled a few systems but not any completely dry like this one. The reason I pulled the pump in the first place was because it wouldn't bleed out and was running roughly if at all. I posted on the subject if anyone remembers. I pulled down the pump and there were some broken springs and rust inside. In short I am not positive it is all together correctly. I am thinking I may be getting air somewhere upstream of the IP. So can someone lay out the proper proceedure for bleeding an injection system and give me an idea how many rotations (battery charges...hours... or any other relative measurement) it should take to bleed the injection system when it is first assembled with air in the pump lines injectors and everything else. Thanks in advance for the help.

chevummins

I was just wondering why no one would reply to my post. I don't guess that bleeding an injection system is that uncommon. I read a bunch of different related topics in the archives. It seems that it should start up fairly quickly and push the air on through...?? I am thinking I may have an pickup hose leaking somewhere. I also had a problem with my '91 but it was just pulling air from the fuel heater gasket above the fuel filter (between the heater and the head).... Maybe I should check that too. Is it possible that the drain on the fuel filter could be leaking air or is that a positive pressure area that would leak diesel and not pull air. Thanks for you guys time. Please give me some response. Thanks again

Redleg

I bypassed my steel lines from the tank with rubber. Is your lift pump wet? Does the lever work? Call Piers and see if they have bleeding issues. They build those pumps too.

Hemi Cat

Sounds like air is getting into your fuel. Are you useing the hand primer and opening up the air bleeds on the filter? Look for a wet spot on the fuel lines or at the tank. If you see a wet spot, fix it. If still in doubt, you could get some clear plastic tubing and splice it in before the pump to watch for bubbles in the fuel or after the pump. make sure you put the fuel hoses back on because the clear plastic is not approved fuel hose but work nice for checking for air.

Redleg

Just FYI, you won't always see fuel when there is an air leak.

Ggg

You could try to pressurize the fuel tank with a few PSI and see if there are any leaks up to the lift pump.
Your bleeder on the filter is under pressure, not vacuum.
The next step would be to bleed the system. I mostly worked on "C" emgines but the fuel system is almost identical. First try the lift pump prime lever and see if there is any resistance. If not you need to bump the engine over to get the cam in the right position. After you have the lift pump ready to prime crack the fuel filter 1 turn. prime till you get fuel out of the filter then tighten it. Next crack the fuel inlet line on the Inj. pump. Prime some more till you get fuel there and then tighten the inlet line. Next loosen the injector line at the farthest injector from the inj. pump. Crank the engine till you get fuel squirting, tighten the line. Then do the same to the next farthest injector. etc.,etc. After 3 or 4 cyls the engine should start. Let it idle a minute or so. If it still has a miss, go back and bleed each inj. one at a time while it is idling.

chevummins

Thanks for the input guys.... I did replace the lift pump with a brand new one before reinstalling the injector pump. I guess my leak may be in the line or the tank I will try some of these things when I get home from work. I knew you guys would pull through. Thanks for all of the valuable input.
-Greg

Monty

So you rebuilt the pump yourself? A full rebuild or just the top end?

chevummins

I guess I did close to a full rebuild. I tore it all the way down except for the rotary vane part. The only reason I stopped there is because the two main springs in the lower portion were broken. One was broken in 2 pieces the other 3 pieces. I had trouble with the truck running poorly and acting like it was running retarded on the timing. Then there was also air in fuel situation which I thought might be a leak in the pump. So I tore it down (in the machine shop I work in) and found the broken springs. So I replaced all the parts in the gasket and seal set an the spring and retainer assembly then reassembled. I have an extra pump so I figured I had nothing to lose. Also I am experimenting with running straight veggie oil and biodiesel and blends there of, so I wanted to see if I could rebuild the ve pump myself then I wouldn't have to fret over the cost of a rebuild if something didn't work out with my homebrew fuel. I know you guys have surely labeled me a "WEIRDO" by now... hehehe but you will have to sign my book to join the ever growing club. I rebuilt the 727 in my 91 a couple of months ago, and those were my 2 issues about entering this diesel world....expensive injector pumps and a lack of understanding of how they work and the unkown magic of the auto trannies that these motors like to eat for dessert. I now own 4 of these trucks within the last year. I told my wife I was going to sell all of our vehicles and "switch our fleet to diesel...cummins of course "what others are there?" Now I am selling my last gasser and have bunches on inline sixes... So there is the skinny. The guy at the diesel performance place told me I couldn't do it. So I took it as a challenge.

chevummins

I thought you might get a kick out of this too. My next dreaming in space project....I am working on a plan to make a GM SM465 granny 4 speed into a super wide range, dual range 6 speed with a double over drive when coupled with a us gear overdrive should give me effective 12 speed with overdrive gears to boot. I am adding two gear pairs and a synchronizer set to the input shaft in such a way that one set will make an overdrive range and the other set will be the stock ratio of the original setup. I am also using this in my 4x4 so I have a 205 transfer with a low range that will be available from splitting the shifter so you can have a low 2wd range. If it all works right it should look like this the tranny alone will go
1st (granny) 6.55:1
2nd 3.58:1
3rd 1.7:1
4th 1:1 (direct drive)
new ratios....
5th .909:1 (overdrive 1)
6th .474:1 (overdrive 2)
coupled with an auxiliary overdrive of .78 you get to split all the first 4 gears a standard overdrive in the 4th over position (.78:1) an higher overdrive in the 5th over position of (.709) which is close to stock with the 518 and 47RH and super high cruising down the flat freeway of .474 in 6th. And in case I want to compete for the land speed record 6th over .37:1 WOW I don't think that one will be feesible.
If you use the 205 approx 2:1 reduction
you could drive like this
1st low low 13:1
2nd low low 7.16 Range change ie. shift into direct in transfer case and first in normal gear box
1st direct 6.55:1
1st hi 5.109
2nd direct 3.58:1
2nd hi 2.79:1
3rd direct 1.7:1
3rd hi 1.33:1
4th direct 1:1
5th direct .909:1
4th hi .78:1
5th hi .70:1
6th direct .474:1 (I calculate with a 4.10 axle ratio about 1300 rpms at 70 mph)
If you dare!!!!!!! 6th hi .37:1
It might just be easier to invent a shrinking gun and shrink a road ranger 13speed down to a size reasonable for the 6bt but I've machines material a brain and 2 out of the 3 sm465s that I will need to complete this project...

I know you don't believe me... but I don't think it is as far fetched as one might think. We will just have to wait and see. And just think about all of those overdrive ratio. You could pick whichever one you neede for the optimum efficiency and load.

wannadiesel

I like your kind of weird. Keep up the good work. I wish I had the guts to put in a 3200 RPM gov. spring, let alone tear the whole pump apart.

Ggg

Chevummins- You might get e kick out of a service truck at LEACH Enterprises. If I remember it correctly it was a mid 60's Ford or Dodge 1 ton with 65 forward gears. Let me see if I can find a link.

chevummins

That sounds really cool!!! 65 different ratios. I bet you couldn't shift all ten levers in that thing. But I worked more on my truck yesterday and still have the same problem, lots of air. I bypassed the tank first and dipped a clear hose into a 5 gal container of diesel. Still the same problem, so then I bypassed the filter and lift pump and put some diesel in a pump up sprayer and hooked it directly to the input of the injector pump. And bled and cranked etc etc.... still the same deal. Next I got to scratching my head and decided that when I got the truck it only had a "miss" problem (possibly due to the broken springs in the injector pump), but i had the injectors rebuilt and replaced them, thus disconnecting the return rail. So I thought this could be a problem so I replaced all of the copper washers on the bypass connections and tried again to no avail. It looks to me like I get a lot of air on the back 3 cyls and not as much in the front. My question is....since I have the tank bypassed, if I had a leak or a crack in the return line....could it cause more air prolems by returning the air to the pump or should it all be pushed down the line back to the tank? If it is possible is ther a way I could bypass it from returning to the pump to eliminate the air going back to the pump, maybe just for diagnosis help. Thanks for your time.
Chevummins

Ggg

I looked on LEACH Enterprises' web site but there is no mention of the truck, oh well. It was just something they put together for show.
Are you getting fuel at the injector lines?
Yes it is possible to be recirculating the air.
If you hook the fuel can/ clear hose directly up to the IP and you go throught the last part of the bleeding steps as before and still can't get the air bled out then you have a IP problem.
Not to insult you, but is it possible the pump is not put together correctly? How about the gear timming? I have seen (don't ask) these off by 1-2 teeth and they prime real nice but just will not start.

chevummins

So in short what you are saying is... If the IP is assembled wrong or still has an existing problem that was not fixed when I did my repairs, the pump would not bleed correctly. Of course it is possible that I didn't get it all back correctly, but I was extremely meticulous about disassembly and reassembly. What makes me wonder is that it is exactly like it was doing before I pulled the pump. Is there a way I could bypass the return lines into a separate tank or something to that effect to eliminate the question of a hole in the return line? I guess I could just reinstall the other pump I have and see if it presents the same situation or fixes my problem all together. I do appreciate your time and wisdom, I am sure you understand that you will never learn anything new if you don't attempt something new. Thanks again
chevummins