Bubbles burping back from MTDI pump

[offalot]

I posted this in the IDI forum, but then saw it might be more geared towards this one.
The pump in question is the euro land rover pump, i put on my TDI conversion. I was just going off the ebay sellers word that it is a good pump.  I timed the pump internally, then then, timed the belt and pulley the traditional way. I've purged the system several ways, opening the injector bungs, pulling vacuum on the return line (for days) I even installed an inline elec. pump. Last thing I did was crack all the bungs, remove the glow plugs and cranked the crap out of it, waisting a bunch of fuel but I'm desperate.  No matter what I do, bubbles come back out of the injector pump back into the feed line.  Ive only got it to chug to life a couple times for a couple seconds.  So is it a bad pump? Is there a way to check?

[libbydiesel]

With the measures you took it should be more than adequately primed to start and run easily, provided it is timed correctly, the vanes in the vane pump are not stuck and it is adjusted reasonably well.  What plunger lift setting did you time it to?  Did you open the pump up or change any settings before installing it?  How long did the pump sit between when it was removed and when it was installed on the current vehicle?

[offalot]

By plunger lift, you mean the measurement taken from the back of the pump with the dial indicator? I cannot remember precisely but I know I did the research per the pump stamping for that specific pump. I did not get into the internals, and I am not quite sure how long it was sitting since. I don't think for terribly long. I've pulled plenty of IDI pumps and used them that were sitting for years.
  I was questioning timing, but, in my head, even if it was 180° off the pump would still be doing the same cyclical function. Sure the engine wouldn't run for crap but it wouldnt explain the bubbles.  Very frustrating.

[vanbcguy]

A bad input shaft seal is one potential possibility. Libby is trying to rule out other potential problems. If the pump is sucking air it'll do what you're saying. If it has been sitting a long time the feed pump may be stuck and not delivering fuel properly. The input shaft seal can likewise fill an otherwise healthy pump with air.


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[libbydiesel]

I don't think that the air you describe is a problem.  As I said in your other thread, having some bubbles in the supply line that move toward the pump when cranking and move back when of is completely normal until you get the thing running.  Get it running and driving and then if bubbles keep flowing to or from the pump then possibly be concerned.

[offalot]

I don't think that the air you describe is a problem.  As I said in your other thread, having some bubbles in the supply line that move toward the pump when cranking and move back when of is completely normal until you get the thing running.  Get it running and driving and then if bubbles keep flowing to or from the pump then possibly be concerned.

Man, as much as I would like this to be the answer, i just don't know.   Since I installed the inline elec. pump, I disconnect the hose at the IP and let the fuel flow into a can until there is no air coming through, then hook it to the IP. Last night I cranked the engine for some time with the glow plugs out and injector unions loose again until there was a significant puddle under the truck. After about 3 minutes my feed had about 6" of air back in it. Air has to be infiltrating from somewhere.

[theman53]

Every time you loosen anything air will get back in. Cracking the nuts loose is great but if you keep doing it you are not accomplishing anything. Leave it all together, get it running. I have had one of my pumps take a long time to get right, 10 minutes of run time before it started to act normal. Also, if you have the return lines messed up or they are old, replace them. Every line attached to the pump or injector can introduce air. Also, check the fuel filter and make sure there was not 2 of the small gaskets or if any of the gaskets are leaking.

[libbydiesel]

I made a shrader valve fuel inlet banjo fitting and an outlet plug.  With those in place, I can pressurize the pump (small pressure) and can use soapy water to find any leaks.  That's worked on more than one pump.  Regardless, with an electric pump in place, there should not be any issue with it running.

[fatmobile]

I know kind of old post but the problem might have been a mainshaft seal leak.
 Feel any fuel behind the injection pump sprocket? The electric pump might have pushed some past a bad seal.