Hello! oh and HELP!... Stubling/Stalling/Hard Start. Sometimes.

[laminaytrap]

So I was told this is the place for IDI knowledge, being a Vortexer who just picked up a 96 Jetta, I thought i'd join the party here.

Long story.
Bought the car a few weeks back for cheap, needed a winter beater and thought this would be fun to drive and build for summer.
Drove to school with it and around GTA/Southern Ontario, put on about 2500km, no serious issues besides lack of floor heat.

Last week I was heading north through the snow storm and the rad froze up. Caught it before the needle passed 3/4, waited for the heat soak to defrost the coolant, continued on my way.

Car ran great for two days then on Thursday we got 2ft of snow and i had to plow my own way down my cottage road. Car ran fine, no abnormal temps or pressures despite the beating it was taking. Didn't make it all the way home, had to walk the last 100ft and left the car buried until the morning.

Next morning I took the blower out and cleaned around the car, started second crank (as per usual) backed it out under its own power and drove home.

The next day the issues started to show up. Fuel was filled to 1/4 Tank
After it being hard to start Friday evening it didn't go very far before i returned and parked it (symptoms below)
Put the car in the garage overnight in case there was a frozen fuel issue.
Started fine the next day, but driving issues continued.
Filled Full of Diesel at Esso. All issues immediately subsided.
Went for a drive later in the evening (had been sitting <12hours -15*C) Hard to start, but did so under it's own power with choke and accelerator help.

Symptoms:

Hard start (5+ minutes of proper cycling and resting until i got it started the first time (cold, had been sitting 12+hours -15*C)
Engine stumbles below 2000RPM, as long as the revs stay up and you stay on the gas it seems to be fine, no apparent loss of power.
Below 2000RPM off throttle you feel and hear a stall until you work the accelerator to make it go again.
Little to no response under 1/4 throttle.
Runs better with choke on, lots of smoke at start and otherwise (this is new, enrichment didn't cause much smoke before)
Will not idle without choke after a drive.
Idle is inconsistent around 800-950. It used to sit at 1000 solid (choke on/off), and did so again just after the refuel.
Can hear a small hissing in the vicinity of the pump after running. (bad seal in pump?)
Appears to be leaking fuel from the Atmospheric Bleed (can it cause the symptoms?)  i have always smelled diesel when driving with the window down. See last Picture (i think its oil will wipe and check)

Things that have been done:

Crank Gear replaced and pinned, new timing belt
Fuel lines filer->pump were replaced with one piece lines in case of leaks.
Filter water trap opened, seemed to be just fluorescent diesel coming out, don't know if water looks a lot different.
Loosened and re-tightened fuel banjo on pump inlet, just in case.
Pulled Thermostat Tee, no signs of cracks, can blow through it, o-ring is in place on filter.

Questions:

Should I pull/replace the lines to the tank and/or pull the fuel sender to ensure everything is in good order back there? Maybe some snow pulled loose something. And all of the rubber hoses can rotate where they are clamped to the hard plastic lines. Is this normal because it is cold? Or are all of these connections now leaking air?

All of the vacuum hoses have be cut at the solenoids on the fuel filter bracket. I assume they are akin to the Salt and Pepper ISV and A/C idle-up valves of MKI/II. I don't think they are an issue but the plunger on the fuel pump still goes to one of them and is open to air. Probably will unplug them and store for later (not priority).

Appears to be leaking fuel from the Atmospheric Bleed (can it cause the symptoms?)

What are my next steps, I've found a few threads with similar issues, but none with resolutions...

Thanks in advance,

Hopefully i can get this thing sorted without buying/rebuilding a pump.

I am going out to re install the fuel filter.

Jon

[TylerDurden]

First order of operations for me, is clear fuel lines in and out of the Injection Pump (IP). That will show if there is air infiltrating the system. Air in the IP causes erratic running: the internals spin at high speed and whip around bubbles which get pushed into the injector lines.

Second operation I do, is to run the engine from a small clean container of fuel in the engine compartment. If it runs well from the bottle, there is an issue somewhere upstream: filter, lines, tank.

[TylerDurden]

P.S. When "feeding from bottle" supply line to the IP and the return should both go to the bottle.


WRT the aneroid chamber leaking fuel: I have had success just opening the aneroid and cleaning the area well. I may have been lucky, that debris like worn metal prevented the pin from sealing properly. YMMV. The orientation of the parts is significant, so mark and photo the pieces as they are before moving them, so they can be returned to their original position.

[laminaytrap]

Just buttoned it back together, replaced all the rubber between the IP and the filter, also the return line to the hard line pulled off in my hand, so it got replaced and re clamped. In the lines to and from the IP I spliced in a short section of the original hard line so I could inspect the fuel.
Seemed to start ok, pretty smokey, and has been running decently since this afternoon. Hopefully it continues to do so.
There appear to be very few bubbles running in from the filter (which I believe is normal) however the return line looks frothy. With a light behind the line you can see that the return is very foamy. I assume there is some air ingress at the IP. Besides the leak in the atmosphere vent is there any way to tell where it might be leaking, or do you normally just go ahead and re-seal the whole pump?

Thanks for the input! I'll keep this up to date if I have reoccurrences of these symptoms.

Jon

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[TylerDurden]

It is very do-able to get zero bubbles in the supply line.

Foamy bubbles in the return are usually from the IP rather than from the injector returns. Foamy bubbles if the supply is running clear, mean the lift-section of the IP is drawing in air; often from the mainshaft seal, sometimes from the banjo fitting.

A leak producing fuel on the exterior of the IP is usually a bad seal in the main body, indicating they all need replacing. Bad body seals can also let air in while the engine is stopped, making starting difficult and erratic running until air is purged.

[Turftech]

Fortunately, 8v-of-fury has a pump resealing service. http://www.vwdiesel.net/forum/index.php?topic=30546.0

[vanbcguy]

Frothy bubbles coming out of the pump with no visible fuel leaks is often going to be the mainshaft seal. It is under vacuum during operation.

If that seal has failed there is a fair chance that the pump mainshaft bushing is worn out (usually due to an overly tight timing belt). If that is the case then just replacing the seal will often result in a new leak in not too long unless the bushing is dealt with.

[laminaytrap]

Thanks everyone for the comments, the issues have returned as expected. @vanbcguy I think you nailed it there, because I put on a belt only a week or so ago, must have been too tight+the bushing was probably already worn to some extent. I guess I'm going to have to rip into this thing, and/or find a spare one. I don't imagine they are too hard to find, seeing as there should be many AAZ motors with slipped crank gears to pull parts from :s.
I'm pretty sure I followed the directions that Vince Waldon posted on his site (excellent how-to BTW) though its likely that with over 600 (likely 1000000) km on the clock things are going to be worn out.
Will look into this more tomorrow, thanks again for all the help!!!

Jon

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[laminaytrap]

So I picked up a pump from a vortexer, but it has the adjustable sprocket from a 97 and it doesn't fit through the hole in my mount bracket.

The pump was rebuilt by Gilles and has a 1.6 boost pin and ~7000km on it.

It still has a cold start lever and all the same electrics and whatnot as my old pump.

If I machine out the hole in the bracket will this pump still bolt up and work like stock?

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[burn_your_money]

You can machine your bracket but you also need to change the metal inner timing cover and you need to get a 2 piece pump pulley if that was not included in the sale.

[laminaytrap]

Cool thanks! I have the pulley and timing tools from the sale, bracket will hit the machine shop tomorrow, timing cover will be trimmed.
Hopefully all goes well

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[burn_your_money]

It's more than just trimming the cover. But it should all be doable.

[vanbcguy]

For what it's worth, I had my timing cover completely opened up to the larger size.  For my "late" style pump it actually only needed a notch cut as the larger part of the pump snout doesn't stick through the mounting bracket, it is flush with the edge of it.  So really a quick trim with some snips would have done fine.

[laminaytrap]

I suspected as much, will know for sure in a couple hours

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