NoSparkplugs

Ok, a few of you may have read my lift pump install thread a little while back and after the install I got a bunch of air in the lines. I bled the lines and I figured I was good to go... no dice. Its still got air in the system and I can't seem to get rid of it. I bled it through the nut above the fuel filter about 3 times, I cracked my injectors and bled them, ok 3 of them since I ran out of time and the thing started firing up on me. If it helps, I ditched the stock quick disconnect system on the lift pump and went to hose and clamps instead. I'm pretty sure its sealed but anythings possible I guess. Also when I was tightening the inlet line on the LP I figure I might have overtightened it since I heard a strange "crack" noise. Could I have cracked the new lift pump by over tightening it? I used a bit of teflon tape to seal it up, maybe thats why it made the noise? Dave also mentioned that the fuel pickup line on the fuel tank can crack and cause an air leak.

I'm going to do the following:
1) Look at the pickup line for cracks and seal any cracks.
2) Bleed the injectors (all of them, yes I was stupid only to do 3)

Which brings me to another question, when bleeding the injectors do I crack one at a time or all of them and when fuel/no air is still being pushed out (IE cranking the motor) tighten it down and move on to the next one?

Thanks

Lucas

Chrisreyn

Lucas, on bleeding the injectors, I wa told its like bleeeding brakes, start at the farthest one first and work towards the pump....its worked for me.
I have also seen several posts on here that mention to NOT use teflon tape on the fuel lines. I cant give you a reason, but have read that over and over.

I just bled my fule lines Sat. I crack them, crank it over till fuel comes out in a good stream, then tighten it down and go to the next one.

Hope this helps............CD

apwatson50

For bleeding the injectors you don't have to do one at a time, I usually do about 3 at a time and thats what most people will recomend. Just crack 3 turn over untill fuel starts coming out then tighten them down.

If you heard a crack I would bet that you cracked the lift pump housing and that is where the air is coming from. Your best bet would be to replace it again and not tighten the fitting down as much. I believe its a tappered thread so no teflon tape is needed and you really don't need to tighten it too much.

Boatnik

"NO teflon tape" is good advice when working fuel systems. If it is not used VERY CAREFULLY small shards of tape get into the system and plug up the small passages in the injectors and IP. I have been informed at work that Dupont doesn't classify their tape as a sealant. They call it a lubricant go figure! We have been plaqued in the past with a series of tapered pipe connection leaks that we attributed to poor choice of sealant and inadequate cleaning of the threads prior to appling the sealant.

wannadiesel

You should not have to bleed air out of the injector lines except to start an air-bound engine. Even then, bleeding 3 will get you running and the rest will clear themselves out. The air will work through in a matter of minutes if no more air is coming in.

You are still getting air in the system, most likely on the suction side. Read: cracked lift pump or supply line.

Boatnik nailed it on why the "no tape" rule. The purpose of the tape is not to seal the threads. It's to lubricate the threads so you can tighten the fitting enough to get a good seal. Pipe dope is a sealant.

Underpsi

so is it ok to put pipe dope on the threads then?

NoSparkplugs

Well I'm gonna tear into it this weekend. I have some epoxy like putty that hardens up like a rock in 15-20mins, that I'm going to seal the LP with if the crack isn't super serious. Now don't jump to conclusions , I'm only going to run that as a quick patch until I get my hands on another lift pump.

So from what I understand with the bleeding, the injectors will eventually push the air out themselves. After I get the LP all installed and buttoned up, just crack the bolt above the fuel filter and push the priming lever on the LP and I should be good to go?

****, I'm getting excited, its no fun not being able to drive the CTD .

G1625S

If there's already some fuel in the system, crack the bleeder at the filter block and pump till there's no bubbles. Close that up and crack open the overflow on the back of the VE and pump till you get a good stream of fuel. Close that up and crack 1-3-5 and crank her over. It'll run on 3 untill you can run around and tighten the other 3. Only crack the injectors a wee bit--there's a lot of pressure behind there!

WVU Dodge

Just to verify what was said earlier, it is possible to get air in the line at the tank. That happened to my truck when my dad still had it a couple years ago. He had to crack the injectors every day in order to get it started and replaced the lift pump as well. It wasn't until he took it to the Dodge garage that they chased it down to the line losing its prime in the tank.

So just to verify that it does happen, although i dont know how common it is.

Adam

Boatnik

Not being a Cummins tech. I would say use a small amount. You do not want to introduce foreign material into your fuel system, so only put enough sealer to catch the back of the threads on the male end. Also make sure the sealent is OK for petroleum. Some are not. Most pipe threads are tapered as mentioned before. The smaller the diameter the easier it is to over tighten. Generally if you can make up a fitting finger tight then you can go about one revolution more to seat the threads. Less if the piece you are threading into is a casting, which I believe the piston lift pumps fall into this category. Remember you can always go back and snug up a leak if it is too loose. If you break it.............?