It suddenly stopped sucking fuel, fixed.

[rabbitman]

So I got the '92 golf running ok and then I was gonna mess with IP pressure when I found a huge fuel leak out of the back of the pump. I pulled it and found I'd used the wrong O-ring on the cold start advance shaft so I threw the right one on, put it back on the car and after cranking for maybe 20 seconds it fired right up. Here's where it gets weird.

It would only "rev" to a low idle and pushing the go pedal wouldn't change a thing, I did this for a while and noticed through my clear fuel lines that there was no fuel going to the pump.......no bubbles, nothing. It quit shortly after so I rigged a bottle of fuel and got it to start and run just fine off that. So I hook the lines back to the filter and fire it up and all is good for a short time and then the IP runs out and it won't start again.

I blew through the return and feed line and both are clear, I also bypassed the filter with the feed line but it still won't suck fuel AT ALL.

Any clues?

[CRSMP5]

id guess air leak on line.. yea it will suck from a can.. but not from the tank.. id check over all you connections...

else the internal pump failed and now requires a pump to push fuel to it..

[rabbitman]

id guess air leak on line.. yea it will suck from a can.. but not from the tank.. id check over all you connections...

else the internal pump failed and now requires a pump to push fuel to it..

The weird thing is it worked just fine until I pulled the pump and replaced the cold start o-ring, it does suck from a fuel bottle too.

Is there some kind of valve in the feed line that coulda shut?

[ORCoaster]

Did you forget to tighten the lines on the filter, or washers on the inlet?  Maybe the new O ring is still too small or not sealing there.  Sounds like a basic air leak to me.  Go back to what you touched last and source it out.  Cover plate not tight or on crooked?

Gotta be something very simple.

[CRSMP5]

thats why i say check all the connections you touched.. any one of them seeping air will do that... it will suck from a can close to front of car/pump.. but not pull from fuel system... since pump was OFF all your connections need double checked along with the timming plug as it will suck air too.. if you set pump timming...

[8v-of-fury]

since pump was OFF all your connections need double checked along with the timming plug as it will suck air too.. if you set pump timming...

Which i hope was done if he removed the pump lol . Definitely sounds like an air leak.

[rabbitman]

Well I hooked up a clear hose to the feed line so wouldn't drink any diesel and sucked on it with my mouth, very easy to get fuel up there ......

The IN/OUT lines have copper washers and are tight on the pump.

The only thing left is I have the pressure regulator set for ZERO internal pressure so I could get the static timing right without internal pressure throwing things off (yes it's trial and error), and I'm pretty sure the little vane pump draws a lot less fuel at that setting so maybe it just ain't enough to get it up to the pump. It's weird that it worked yesterday with the wrong o-ring though.

I gotta wait 'til evening when I'm the only one here to run it since it's rather smoky so I'll get back then.........

[ORCoaster]

Internal pump pressure set to zero for what reason?  Tap that sucker down about a 1/4 inch or better yet get a gauge on it and set it for 40 lbs at idle.  No where have I read or heard do you need to do that.  So stop doing it.  Then try it.

[rabbitman]

Internal pump pressure set to zero for what reason?  Tap that sucker down about a 1/4 inch or better yet get a gauge on it and set it for 40 lbs at idle.  No where have I read or heard do you need to do that.  So stop doing it.  Then try it.

My thinking is that if I get it so it starts good with zero internal pressure then the static timing is good. I don't want it to start up and then clack more and more as the pressure rises and the timing advances at idle.

Also this is the pump that wouldn't get above 35psi at 1000rpm.

But yeah maybe I'm straying from the tried and tested methods.

I do have a gauge setup so that won't be a problem.

So far nothing has explained why it worked fine until after I changed the o-ring.

[ORCoaster]

You have had the pump apart and know that pin that goes into the ring that holds the 4 roller bearings is connected below the pump to WHAT?  To the advance mechanism and cold start lever.  And on the other side of the pump is a cover plate that keeps some shims and a BIG honking spring from falling out.

That spring need to be compressed with internal pump pressure before advance occurs.  Granted some advance happens early but at idle no advance is supposed to be happening at 40 lbs of pressure.  That is why the advance of the cold start level is all mechanical, lever twists on cam that pushes piston and mechanism over to develop about 2 degrees advance. 

Now why do you have an air leak?  O rings not of proper diameter and thickness?  Top screwed down tight?  That is a big gasket and mine needed several rounds of back and forth half turns on all screws to get it down tight. 

Did you pinch and O ring and take a piece out of it?  Done that a time or two on o rings.

Nut on top the throttle tight as it can go?  It pulls up on the shaft and seats the o ring in the underside of the cap up tight. 

You can see I am grasping here to figure out where all the mystery air leaks seem to come from.  That is all I can think up right now. 

Keep looking.

[rabbitman]

So I tapped the regulator down a little bit (less than 1/8th inch) and fired it up, now it sucks fuel........why now and not before? I guess higher internal pressure makes it have to flow more.

Now it rattles waaaay too much, I should've swapped the gov shaft sleeve for one without the bleed hole since I think it's messing up the 43psi @1000 idea. So I need to know the proper internal pressure for this pump.

This pump: 068 190 081N

Rabbits pump: 068 130 107AG

[ORCoaster]

Pressure inside the IP would still be the same, 43 lbs@ idle.  Having the hole in the sleeve is for lubrication in my mind.  It all floats inside the same housing and look where you are measuring the pressure.  Just below the out bolt?  With a second banjo bolt?  or did you super it up so you have a gauge drilled and threaded in the side of the pump in that nice 1/4 inch sunken flat spot?

Most pumps I deal with have to have a positive output in order to sphion up additional water or fluid to charge the pump. 

You said the vanes on this pump were not stuck so can you tap on that pin again and up the pressure past 35# now?

If not there must be air in the system or wear in the main chamber someplace. 

Let us know. 

[rabbitman]

Here's a picture on the second page (not my pic) of a sleeve like my '92 has. In the pic you can see the hole is like a slot. What you can't see is the "vent" holes under the guy's thumb.
http://www.vwdiesel.net/forum/index.php?topic=30187.1

My rabbit does not have the slotted hole, just the vent holes. I'm pretty sure the vent holes are just so the sleeve can slide on the gov shaft without getting any pressure or vacuum inside the sleeve.

[ORCoaster]

The shaft and the sleeve are immersed in the diesel fuel that is pressurized to what ever amount the regulator is set to.  I believe the vents are for lubrication purposes.  There may be a slight build of pressure or vacuum on the two parts as the sleeve slides up the shaft as RPM's increase but the counterweights pull it back as they collapse as the RPMs drop.  The sleeve locks into the base of the four pieces.  Or am I whacked on that?

So I don't think the vent holes have a thing to do with the pressure inside the pump.  It is a mechanically driven operation that works in a fluid filled environment.  Does this make sense?

Part 115 just slides on part 108.  The little triangles, 805 make it move.

[rabbitman]

Hey thanks for the picture, no your not quite wacked haha.

I did forget to say that #108 is drilled up the middle and has a hole near where the o-ring sits on the shaft and another one near the end of the shaft. The sleeve slides and either covers or uncovers the hole near the end thus blocking or unblocking a passage.

The hole near the o-ring has a matching hole in the IP housing so fuel can travel from, I believe, the regulator, up the middle of the shaft and then the sliding sleeve lets it travel out into the housing or not and raises or lowers the internal pressure depending on whether the hole is covered or uncovered.

It's a load/rpm sensing method of changing the timing to help with emissions but it's been a while since I read about it. It was either on this forum or the vwdieselparts forum.

Hope that makes more sense .