no fuel out of pump.what can cause this?

[carrizog60]

i sell a 10mm head to a friend but after installing it it doesent pump fuel out.
swapped to a regular 9mm again and all is ok again.

what can cause this situation?
if the head was from a reverse rotation engine it will still pump diesel,but in a wrong order right?
could the holes in the plunger be plugged?


thanks

[ORCoaster]

The holes in the plunger could be plugged and so could the individual check valves going to the lines to the injectors.  Did the 10 mm pump work just prior to the swap or was it sitting around somewhere?  Is that little washer that goes on the front of the pump in place and is it worn at all.  I stick it to the indent of the plunger with Vaseline so it doesn't move when I am putting it all back together.

[rabbitman]

if the head was from a reverse rotation engine it will still pump diesel,but in a wrong order right?
could the holes in the plunger be plugged?

thanks

I don't think it will pump if it's designed to turn the other way.

I doubt the holes are plugged.

[carrizog60]

ididnt install it.
it was installed by a friend that works on a diesel shop so i assume that it was installed properly.

i bought that head for my use,seller said that it was from audi 80 tdi.
i had it here for more than 2 years but was wrapped is paper and inside a closed plastic bag.

[regcheeseman]

it will still pump but the delivery curve may not be suitable - unless the camplate was swapped?

I had this problem and it needed 3 or 4 turns in on the fuel screw to get it pumping.

[Mark(The Miser)UK]

I'm not a pump man, but the camplate on the QuantumTD[mk2 Passat] or on mine at least, has a completely symetrical profile, rise and fall. I measured it every 2.73 degrees

I suspect that most are, looking at pictures.

I know nothing about heads, but my belief is that they are symetrical.

Naturally if this is so, then the only difference would be the advance mechanism. Could this be put in from the other side? I've never even physically looked at the high pressure pump and sleeve. Is the leakoff channel symetrical?

You did get fuel flowing back to the tank I assume

[vanbcguy]

I'm FAIRLY certain there is actually something in the pump to prevent it from shooting fuel if it is turning backwards.  Diesels after all will run in either direction, and will quite happily inhale through their exhaust ports.  Unlike a gasser if the pump is providing fuel, it'll run either way. 

Hence I believe Bosch designed in something to prevent such a situation as otherwise a stall on a hill could quickly turn in to a very messy situation!!

[regcheeseman]

But the pump body is running in it's correct direction, yes? - so there can be no issues there.

Just the head and camplate which is backwards - it'll deliver no mattter how its timed, so it must be solenoid/fuel screw or assembly

Tried running it from a bottle or an elevated tank?

[vanbcguy]

But the pump body is running in it's correct direction, yes? - so there can be no issues there.

Just the head and camplate which is backwards - it'll deliver no mattter how its timed, so it must be solenoid/fuel screw or assembly

Tried running it from a bottle or an elevated tank?

I THINK the design of the plunger itself in the pump head is what prevents it from shooting fuel if it's turned backwards.  Don't quote me on that though.  Thinking of the pump design that's the only part of the pump that "knows" what way it is turning.  I think there's a groove cut in to the plunger for that purpose?

Only reason we're on to this though is he seems a little uncertain of what direction his particular pump is supposed to be turning.  Your advice is definitely where I'd be starting otherwise!!

[carrizog60]

why turning the fuel screw made it pump?
would the control collar not move enough to uncover the spit hole?

[vanbcguy]

If the fuel screw is not turned in enough you could be below the bottom of the fueling map.  It is possible to have the screw backed out so much the engine doesn't have enough fuel to even idle, much like it is possible to turn it in so much it won't rev down.

[regcheeseman]

why turning the fuel screw made it pump?
would the control collar not move enough to uncover the spit hole?

yes, sort of.

The spill hole remained uncovered so every pump stroke would be wasted, I was actually getting a slight bit of diesel out of the ports. The collar was already off and wound in an extra 1/4 of a turn.
make a reference and turn it in 3 turns, you can always set it back.

I THINK the design of the plunger itself in the pump head is what prevents it from shooting fuel if it's turned backwards.  Don't quote me on that though

sorry quoted! I can't see how the rotation makes any difference. The problem would start if the vane/lift pump ran backwards, there would be no pressure in the pump to prime the high pressure injection stage of the pump.

[vanbcguy]

I THINK the design of the plunger itself in the pump head is what prevents it from shooting fuel if it's turned backwards.  Don't quote me on that though

sorry quoted! I can't see how the rotation makes any difference. The problem would start if the vane/lift pump ran backwards, there would be no pressure in the pump to prime the high pressure injection stage of the pump.

Found this on a site describing the VE pump... unfortunately Figure 11 was missing:

Reverse-Rotation Prevention

It is possible for the diesel engine to start in the reverse (opposite) direction of normal operation. The VE pump does not allow this to happen, Figure 11. If the plunger were to rotate in the reverse direction the intake port would open during the injection stroke, preventing any pressure buildup.

[rabbitman]

Found this on a site describing the VE pump... unfortunately Figure 11 was missing:

Reverse-Rotation Prevention

It is possible for the diesel engine to start in the reverse (opposite) direction of normal operation. The VE pump does not allow this to happen, Figure 11. If the plunger were to rotate in the reverse direction the intake port would open during the injection stroke, preventing any pressure buildup.

I think you're correct, when I had my pump apart a couple years ago I remember studying it and I'm almost 100% sure that I figured out that it wouldn't pump backwards. Seems like if it is spun backwards the plunger would try to push fuel the wrong way, like back into the pump rather than into the injector lines.

[Mark(The Miser)UK]

Google reverse/backwards diesel engines, and you'll get oodles...