Ran out of fuel...researched and still not running

[Insanefury]

**Reposting this in B4/MK3 forum**

Hi all,

I've recently bought a 1996 Passat TDI. Has about 258k with recent work done to the suspension, head, and IP, in addition to a new timing belt at 245K. It was in limp mode and dumping black smoke out the back when I got it. With a little investigating I found a hole in one of the vacuum lines and did a quick repair to get it running much better. Now fast forward a few weeks...

Driving home from work about a week ago, I was coming to a light and the engine began to hesitate and sputter eventually stopping and was unable to be restarted. The tank was at 1/4 but I remember the previous owned mentioning what a PITA it was when he ran out of gas; hmm.

I tow it to my house and begin researching about priming the filter, lines, and IP. I figure while it's down I can take some time and service anything else that was neglected over the years. Things that were needed and repaired:

-Intake carbon/soot removal, had about 5mm of crust inside...got that out and made sure the EGR was functioning.
-Replaced all vacuum lines, including the one inside the ECU & added Malone Stage 1 chips.
-Replaced the black original relay 109 w/ a new grey one.
-Replaced N-75 valve.
-Drained about 8 oz of oil from the IC; flushed & dried it.
-Cleaned out the various IC/intake plumbing.
-Replaced fuel filter, thermostatic tee, fuel lines (clear) suitable for running B100 eventually, and added inline prefilter; deleted 5th injector.
-Replaced V-belt, tension roller, and accessory belt.
-Fabricated air/oil separator.
-Replaced battery.

So it's all put back together and I begin to prime the fuel system. I have followed the DIY direction several times but I am having some issues.

1) When priming the lines, there seems to be a lot of air in the fuel (frothy).
2) After priming, I crank the car and fuel does not move in the lines.
3) I have the injector nuts cracked and there is only a small amount of fuel sputtering out from all but the 3rd injector, which is dry.

There are several "theories" such as dead IP (although it was supposedly replaced or rebuilt 13k ago) or perhaps the lift pump has sucked up gunk, etc. and has clogged. I've been researching online and dug up some information on some kind of fuel shut off in the IP, not sure if this is the culprit.

Either way, at this point I need the advise of those who have been around these cars as this is my first diesel experience.

Any help would be GREATLY appreciated!

*Update: I've noticed brown chunks (unknown composition) in prefilter. Put in a new one and pulled fuel from the tank through it and have seen more debris.

 

[TDIMeister]

Could be a bad flash of the ECU (happens). Put the stock chip back in or another known-good BK/GQ ECU. Alternatively, put your ECU into another Passat to test.

 

[edjet]

I just had a buddy run his 97 Passat out of fuel with similar results. I found using my oil extractor the fuel from the filter would suck back toward the fuel tank. So I removed the fuel pick up unit and cleaned it , as well as an in line check valve located about 5 or 6" from the tank in the supply line. It had some black crude that I was able to clean out of it with some spray cleaner. I put everything back together, and had good fuel suction at the filter and to the pump, with no fuel wanting to return to the tank in the supply line. After a good IP and injector bleeding, she was back up and running.

I have seen several of the MKIII with similar problem in this check valve in the fuel supply line coming off of the fuel tank.

 

[Insanefury]

Appreciate all of the replies,

I've taken the past 10 or so days to slowly work through the fuel system:

-removed/cleaned tank; replaced all hoses with tygothane tubing.
-removed in-tank pickup/return; disassembled/cleaned unit.
-removed/cleaned/tested both send & return check valves, as well as the "level/ball" check valve that resides near the fueling spout.
-removed/cleaned/modified the vent; replaced hose with polyurethane type.
-removed/cleaned the rubber thingy that connects the tank spout to the quarter panel; it also has a drain and a hose that connects the "level/ball" check valve.
-cleared out the hard lines with compressed air.
-replaced all fuel line (aside from the OE hard line running from the trunk to the firewall) and fitted everything w/new 360° clamps.
-installed a new primed filter. (in case there was an issue with the other one)
-primed all the lines; setup a gravity feed directly into the IP.
-tested fuel cutoff solenoid; it clicks when engaging the ignition.

Noted discrepancies:

-Upon opening the access hatch in the trunk, both fuel lines were badly deteriorated and their clamps had nearly rusted off.
-I siphoned a little under 5 gal of fuel from the tank. Subtract the 4+ gal I added after the incident left less than 1/4" fuel in the bottom of the tank. The fuel level sensor was incorrect and I definitely ran out of fuel.
-While cleaning the in-tank pickup, large blobs of brown goo had accumulated in the bottom and clogged most of the screen.
-The send check valve was partially blocked and allowing flow in both directions. Soaked it in cleaner and cleared it out with compressed air; it appeared to have returned to working condition.
-Noticed and corrected a small air leak in one of the fuel lines. It was responsible for the foamy fuel going into the filter.
-Obscene amounts of dirt caked around the tank, especially behind the inlet. Probably didn't cause any issues but was pretty shocking!

I begin to bleed the injectors:

-cracked the nuts on all four injectors; attempted to start the car.
-cranked for about 6 seconds and then paused for about 30; repeat, etc.
-Injectors #1 & #2 foam fuel at first, then begin to spit out clear fuel.
-I tighten them and continue; injector #4 spits fuel (although not as much as #'s 1 & 2) and injector #3 is not visibly weeping fuel.
-I pull the nut/line back on #3 and can see there's fuel in the line but it's not very much.
-I repeat the process of cranking (attempting to purge the air) and can see air moving out of the IP through the return line; it bubbles out the other side of the thermostatic tee going back to the tank.
-eventually bubbles stop appearing in the return line, however the car will not run.

So at this point I'm wondering if the problem is related to the IP? Perhaps the injection timing has some how slipped or the IP itself is not functioning properly? Or maybe there is still air in the IP? I have replaced the soft return lines from the injectors and can see air bubbles inside. They do not move when cranking the starter or when pulling fuel through the IP.

I will be purchasing a Ross Tech VCDS soon as this seems to be a necessary tool in the TDI belt.

Again, thanks for the help!

 

[Baron VonZeppelin]

Sounds like the Inj Pump still isn't purged/primed enough.

And maybe you don't have a MightyVac or siphon device to pull fuel/air through the Inj Pump.

Next best thing would be to remove the end cap from the return union on the top of the Inj Pump - hook a drain hose to it and into a container.
Set up your gravity fuel and raise it up high - it should start pushing some flow out of the hose you connected to the return union and get the pump primed/purged well enough.

Might be a good idea first to completely remove the union and clean the ports out, since you have serviced all the rest of the system.

Once you get some steady solid fuel flow from the gravity deal you should be able to get the injection lines to prime.

If they want to be stubborn, drag the car about 1/4-1/2 mile in 3rd gear while alternately switching the key on and off. The reason for the key switching is because the fuel solenoid usually only energizes for 2-3 seconds unless you engage the starter. Or use a jumper wire on the solenoid while dragging.

Crack all 4 injector nuts loosely and stuff some old rags/towels/t-shirts around them to absorb the mess. And do the drag.
Its much more proficient than using the starter/battery - especially on a stubborn specimen.

You seem pretty certain you ran out of fuel and have an improper gauge.
But at some point you should still confirm the crank/flywheel - cam - inj pump timing parameters at #1 TDC , to also be certain the crank sprocket isn't moving on the snout.

I'm near Greensboro if you need any hands-on help.

 

[vtveg]

**Reposting this in B4/MK3 forum**
Hi all,
I've recently bought a 1996 Passat TDI. Has about 258k with recent work done to the suspension, head, and IP, in addition to a new timing belt at 245K. It was in limp mode and dumping black smoke out the back when I got it. With a little investigating I found a hole in one of the vacuum lines and did a quick repair to get it running much better. Now fast forward a few weeks...
Driving home from work about a week ago, I was coming to a light and the engine began to hesitate and sputter eventually stopping and was unable to be restarted. The tank was at 1/4 but I remember the previous owned mentioning what a PITA it was when he ran out of gas; hmm.
I tow it to my house and begin researching about priming the filter, lines, and IP. I figure while it's down I can take some time and service anything else that was neglected over the years. Things that were needed and repaired:
-Intake carbon/soot removal, had about 5mm of crust inside...got that out and made sure the EGR was functioning.
-Replaced all vacuum lines, including the one inside the ECU & added Malone Stage 1 chips.
-Replaced the black original relay 109 w/ a new grey one.
-Replaced N-75 valve.
-Drained about 8 oz of oil from the IC; flushed & dried it.
-Cleaned out the various IC/intake plumbing.
-Replaced fuel filter, thermostatic tee, fuel lines (clear) suitable for running B100 eventually, and added inline prefilter; deleted 5th injector.
-Replaced V-belt, tension roller, and accessory belt.
-Fabricated air/oil separator.
-Replaced battery.
So it's all put back together and I begin to prime the fuel system. I have followed the DIY direction several times but I am having some issues.
1) When priming the lines, there seems to be a lot of air in the fuel (frothy).
2) After priming, I crank the car and fuel does not move in the lines.
3) I have the injector nuts cracked and there is only a small amount of fuel sputtering out from all but the 3rd injector, which is dry.
There are several "theories" such as dead IP (although it was supposedly replaced or rebuilt 13k ago) or perhaps the lift pump has sucked up gunk, etc. and has clogged. I've been researching online and dug up some information on some kind of fuel shut off in the IP, not sure if this is the culprit.
Either way, at this point I need the advise of those who have been around these cars as this is my first diesel experience.
Any help would be GREATLY appreciated!
*Update: I've noticed brown chunks (unknown composition) in prefilter. Put in a new one and pulled fuel from the tank through it and have seen more debris.

I'm guessing this might be part of the problem

 

[annieneff]

Seems like if you're not getting fuel at the 3rd injector and you sucked up a bunch of brown crap from your tank... That that's the problem. Either the pump is clogged, the injector line is clogged, or the injector. Doesn't matter how new/old the ip is, if you sucked up the stuff that's been fermenting in your tank for who knows how long; that's chaos on steroids.

With my current b4 I can just about run it dry, but with my previous one it didn't like it when I got to, or below about a 1/4 of a tank. I never questioned why, I just filled it up. If you only have 4 or 5 gallons in there, you might put double or triple that amount and see if that helps.
No fuel at one of the injectors though makes me think that's it.

Crack the 3rd injector line at the pump (instead of on the injector) and see if it squirts there. You can narrow down what might be blocked from there...

Andrew