Died on Highway: Fuel Issue

Nevada_TDI

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Aug 17, 2008
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Reno, sort of...
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2001 Jetta TDI
I am just going to throw this out there: in the fuel sender unit there is a "triangular" check valve in the supply line that even the smallest amount of gunk will hinder. I destroyed an IP by it having insufficient fuel flow to keep it lubricated and it chewed itself up internally. OP, you definitely have air inclusion somewhere, but having to apply 10 inches of vacuum to get fuel flowing from the tank also suggests the triangle valve may be plugged up.
 

AndyBees

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May 27, 2003
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Southeast Kentucky
TDI
Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Relay 109 is bad replace it, it should start right away

The OPs initial post starting this Thread, states that Relay 109 is the first thing he checked on a long list!

1. Checked for relay 109 symptoms...none

....


 
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wonneber

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Oct 12, 2011
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Monroe, NY, USA
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2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten

AndyBees

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May 27, 2003
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Southeast Kentucky
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Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
Wonneber, thanks for that link. (seems I saw this the other night when I was surfing for info)

I have one IP that needs a complete re-seal and another that is a leaker with other issues. I cannot wait to dig in and learn a little more about these things! As you may know, back in the fall of 2012, I had to pull the head completely out on the IP due to the O-ring getting stuck! But, I got 'er back together and it's performed really well.
 
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hey_allen

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Joined
Nov 25, 2006
Location
Altus, OK
TDI
2000 Jetta TDI
Regarding the restriction valve, I believe the formal name was "Case pressure regulator valve", and it is what the banjo fitting on the return hose hard line is secured to.
I was talking with DFIS PDX a few weeks ago, getting ready to send in an IP that would not prime, and they mentioned the valve, asking that it be sent in with the IP. A quick examination of mine showed that it was failed open, the check ball actually rattling around in the valve, instead of being held against the seat under spring pressure.

Apparently it is supposed to maintain the IP at around 15 PSI, before venting excess fuel back to the tank.

edit:
I just checked on IDParts, and their listing for the valve is "Injection Pump Fuel Return Valve" located here if anyone is interested.
 
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tacolifestyle

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Joined
Mar 16, 2017
Location
Detroit, MI
TDI
2003 Jetta Wagon
Took a few days away from working on this car due to workload at work. Some updates:

I had left the car sitting after running it on a jar of fuel at about the same elevation of the IP hooked directly to the IP. The clear line going into the pump ended up with a small bubble in it. This was, as discussed above presumed to be to all the aeration of the priming process and sucking in a bunch of that dry line. This bubble never increased over the course of 4 days.

Yesterday I went out to have a look in the fuel sender. The screen had nothing really heavy on it but more of a dark gray or black film. I pulled in apart to look inside and there was some larger particles in the chamber nothing noteworthy in my opinion. It was mostly light black slimey coating in the bottom and creeping up the sides. I cleaned all this out and wiped down. I then elected to drill out the sender as recommended here, flushed and blew all the particles out of there. I reassembled, started right up, drove around the area for 20 minutes to get the car fully warmed up and parked overnight.

When I shut it down I popped the hood to see if any air was accumulating in the sight line. There was none. About two hours later I checked again and nothing had accumulated there. Today, about 24 hours later, I can see a 3" bubble in that line. That seems like way too much.

In my thoughts any air in that sight line comes from the pump or the filter. Any air leak at the elbow fittings or near the tank would accumulate at the elbow fittings because it is another high point. I need to run it from a jar of fuel on the ground to simulate the back syphon suction directly to the pump. If that checks out it's down to the banjo fittings on the filter head, the handful of clamps for the barbed connections, the thermo-tee & o-rings and the actual filter seal. Beyond that it's only the fuel lines themselves.

Thanks to everyone for helping me through this. I've done a lot of work on this car over 15 years of ownership and hope to give it to my 16 year old this spring.
 
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tacolifestyle

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Mar 16, 2017
Location
Detroit, MI
TDI
2003 Jetta Wagon
Latest:

Yesterday I replaced all the injector return lines and both lines from the filter to the IP with clear teflon PFA tubing. The small return lines got pinch clamps and the large diameters got bolt band clamps. I also replaced the crush washers at the banjo fittings and the thermo-tee.

Last night I started it up, took a drive and all seemed fine. I was not seeing much if any air in the return fuel line while running. None in the line going into the IP once the air in the filter head finally bled out.

Upon shut down I got a thumb sized bubble in the input line that came out of the IP. I got bubbles on either end of the return from the IP to the filter. They were a series of small 1/4" at the filter and smaller still at the pump.

This morning when I went out the original thumb sized bubble remained in the input line between the filter and IP. There was also another bubble about 3" long extending from the filter head in the same line. The return line had a near identical bubble which makes sense if the thermo-tee opens and the return line to the tank becomes dry (I think).

The car started pretty fine this morning. I wonder if that bubble was always there but now that I have clear lines installed I can now see it. Thoughts?

I drove the car to work today and will look before I leave to see if anything has changed.

 

hey_allen

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Joined
Nov 25, 2006
Location
Altus, OK
TDI
2000 Jetta TDI
Please don't use PhotoBucket, they changed the image hosting and your images are only visible to you, unless you want to give them $400/year for hosting the pictures.

That said, good to hear you seem to have fixed it, and thanks for sharing the results!
 

tacolifestyle

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Joined
Mar 16, 2017
Location
Detroit, MI
TDI
2003 Jetta Wagon

This is the photo from this morning. Doesn't look great but it started fine.


This is the photo after 8 hours in the parking garage at work. It was parked with the left front corner on the higher ground so the bubble is in a different location. It started then died when the air was sucked into the IP. It then restarted with a bit of effort. Drove it across town in the snow to get the kid from school. Stopped to fill it up as I could not remember if it was really at 1/8th tank or if I might have a fuel sender float issue from pulling it, drilling and re-installation. I went to unscrew the fuel cap and it didn't want to turn. It was like it was binding on the tether but having filled the car up a million times over the years I wasn't even thinking much about the process as occasionally the tether has gotten twisted on reinstallation but I have always made it right and turned the cap until it clicked. I then turn the cap to tighten it and it clicked. I then unscrewed it normally. I think the tether either was caught under the cap or the cap just wasn't all the way on. This is the first clue to anything being amiss in this system I have seen.

When I returned home I checked to see how much air appeared when I cut off the ignition. I saw no air enter the fuel lines at shut-off this time. I will verify in the morning but I think I may have found the culprit.

I'm a bit embarrassed that if it was this elementary but after 290,000 miles I have never had the fuel cap end up not getting back into the locked position. I did verify that it was the wife who filled it last. To her defense it was about 2 degrees that morning.
 

UhOh

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Great reporting. Looking forward to hearing how this goes.
 

maxmoo

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Lakefield, Ontario, Canada
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2000 golf, 2001 golf, 2000 beetle, 2003 wagon, 2004 golf, 2004 jetta, all diesels
I'm not sure, but maybe someone else knows, do those filler caps have a vent that could be cloged or is the vent somewhere else in the system and could it be blocked?
 

Genesis

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Feb 26, 2003
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Sevier County TN
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'03 Jetta Wagon
There is a negative-pressure vent in all fuel tank systems; if there was not the tank would literally collapse or the engine would be starved for fuel. Since tanks are relatively thin-wall and not pressure (or vacuum) rated they would collapse.
 

maxmoo

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2000 golf, 2001 golf, 2000 beetle, 2003 wagon, 2004 golf, 2004 jetta, all diesels
There is a negative-pressure vent in all fuel tank systems; if there was not the tank would literally collapse or the engine would be starved for fuel. Since tanks are relatively thin-wall and not pressure (or vacuum) rated they would collapse.
I realize that but where is the vent in these mk4's?
If it's in the cap like most other vehicles it would be easy to swap caps to see if that solves the issue.
A partial blockage may cause the op's problems.
 

tacolifestyle

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Mar 16, 2017
Location
Detroit, MI
TDI
2003 Jetta Wagon
This is what was observed this morning. Remember I filled and vented the tank last night then drove about 15 miles home.



There was only a very small bubble from the IP in the feed line. The long flat bubble in the feed line appeared sometime overnight. This clearly came from the filter area as every other connection is at another high point. I imagine that there will always be some air trapped at the top of the filter or dissolved in the fuel. How much isn't clear however. The other thing I noticed immediately was the return line remained full of fuel with no bubbles at all. The car started pretty normally for a 14 degree morning.

I will be monitoring this every morning from here on out. I am curious to see how the bubble size changes over time through either the bleeding out of any remaining air in the filter head, the reduction in fuel level in the tank or any other changes over time. For now, although the vehicle is operating pretty much as expected from a user standpoint, I will be calling this inconclusive until I cycle this full tank down to near empty.
 

Tdijarhead

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Nov 10, 2013
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Lawrenceville PA
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2003 TDI Jetta Daughters Car, 2001 TDI Beetle, Wife’s car, 2005 Golf TDI Mine, all 5 spds
It would be interesting to know if temperature has any effect.
 

wonneber

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Monroe, NY, USA
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2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
I thought the cap opened the vent when it was on.
Doing the ventectomy leaves it open to outside and you can fill the tank a bit more.
If not then I have a leak somewhere.
I ran a smoke machine through the fuel cap and looking from the bottom there was something leaking way up near the cap.
Couldn't exactly see what it was.
 

AndyBees

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May 27, 2003
Location
Southeast Kentucky
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Silver 2003 Jetta TDI, Silver 2000 Jetta TDI (sold), '84 Vanagon with '02 ALH engine
For what it is worth, my 2000 Jetta has had air going through the clear fuel line from when I first purchased it in March of 2003. Changing the filter and O-rings down through the years never changed anything. In almost 350k miles, (without all the details) there's been one incident that was no doubt fuel filter related that required changing the filter and bleeding the injector lines to get the engine going again (wouldn't start after shut-down, warmed up engine).
 

tacolifestyle

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Mar 16, 2017
Location
Detroit, MI
TDI
2003 Jetta Wagon
Latest update:

There is still an issue with air entering the system. I have monitored it for about a week now and it looks like I still have work to do although some things have improved.

1. Upon shutdown I can now see a slow stream of 1/8" bubbles that enter the clear return line between the filter and IP at the filter side. Wiggling the ThermoTee changes nothing (it is new).

2. Upon shutdown I get one 1/4" bubble in the intake line btwn the filter and IP from the IP which remains consistent through as long as a 2 day shutdown period.

3. Upon shutdown and slowly with time air gathers in the intake line between the filter and IP. In my flat garage this bubble is typically about 2 inches in the morning.

4. If I park with the right front corner uphill in the parking garage at work I get a longer bubble in the intake line near to the filter. This can be up to 4 inches long.

Car starts in varying degrees stumble from nearly none to a stall each time. It is dependent obviously on the air in the intake line. Placing the clear lines has helped to see exactly what is happening. I am now confident the everything on the IP side of the filter is good. The different parking situations result in different situations based on where the high point of the system might be. The high point acts as a trap to capture the air. Also of note is that it runs fine once started. I have yet to see any bubbles into the system once up and running. Seems to be a negative pressure issue on shutdown.

Next steps:

1. Pull both lines at filter going back to tank. Pull both lines at sender and plug. Pull vacuum on each to see if any fittings in between are allowing air into the system. I don't suspect that air from any of those locations would gather at the filter due to other high trapping locations.

2. Pull filter to inspect seal. Given where the bubbles are settling this is seems like a likely suspect now that all crush washers at the banjo fittings have been changed along with a new thermo tee.

3. Add 360 band clamps to both fittings at filter on lines coming/going to tank. Could be something there allowing air into the system.
 

tacolifestyle

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Mar 16, 2017
Location
Detroit, MI
TDI
2003 Jetta Wagon
I had time tonight to do #1 from the next steps above. I pulled vacuum on the supply line by pulling the line off the banjo fitting at the filter, disconnecting the line at the sender and plugging. I was unable to hold vacuum on this line. I then did the same on the return. It held vac up to 30 in Hg. I went back to the supply to make sure all the fittings were tight and the end was plugged. The same result of steadily losing vacuum at a rate of 1 in Hg per second in my estimation. I then pulled the fitting at the fire wall and plugged it while pulling vacuum at the filter end. Similarly this steadily lost vacuum but at a faster rate than the rearward line. My gut kept telling me I did have these end plugged properly so I tried that other return line again which did hold. It appeared by my inspection that all of these female fittings are the same. I only had one plugged that looked to fit in the mityvac kit. Anyone have a particular way to plug these that is surefire. I think I had it right but am left wondering.

So it seems that the supply line may have some porosity to it in each of the sections. I opted to swap the lines at both ends so to have the line that held vacuum as the supply and the suspect one as the return. I couldn't think of any reason not to do this. I started it and took it for a drive to fully warm up. Upon returning home I observed the clear lines and could see the occasional bubble still in the supply line. Could be residual air in the filter head or lines? I had not previously seen this condition. I then parked it in the garage. Upon shutdown I had a series of small bubbles forming in the now clear return line. The supply line had one small bubble appear near the filter. I will take another look in the morning to see where things settle.

This is either a breakthrough or at least something else eliminated in the process of troubleshooting.
 

tacolifestyle

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Mar 16, 2017
Location
Detroit, MI
TDI
2003 Jetta Wagon
More update with some success...

Friday (three days ago) I decided to rethink the vacuum leak on the lines back to the sender. I pulled fuel through the sender to see if it flowed easily. It did. That was something I had not previously checked but wanted to eliminate that possibility. I then re-torqued the banjo bolts on the filter head thinking that is a point where air infiltration while running could have been occurring. I also pulled the filter to see if maybe there was a damaged seal. I did not see anything out of the ordinary. I lubed the seal and reinstalled to hand tight plus one turn with two strap wrenches. It restarted fine and I noticed no air in the incoming fuel to the IP as previously happened intermittently. I then drove the car to a few places on Friday then park in the garage for the night. On Saturday morning I went out and the incoming fuel line from the filter to the IP had only one small 1/4" bubble in it. This was the best I had seen in over a month. I did still have air in the return line near the thermo-T. It again started great, drove for the day and parked again. Same situation with no air to speak of in the intake line for three mornings now. I can only assume I did not get the filter tight enough or there was something causing it not to seal. That same could be said for the banjos.

I did however observe at one of these start ups that the air in the return line can get sucked into the filter when it is cold and the thermo-t is recirculating the return line to the filter head. Ideally I believe I should have no air in that line either. I pulled the hold down and modified that so the tee sits flat on the filter head and both o-rings are inserted fully. It seems I have some more work to do here to keep air from getting into that line. I am going to try the teflon tape under the o-ring trick and maybe some additional sealant (Hylomar Universal Blue) there.

I did switched the fuel lines back to their correct and original locations.
 

wonneber

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Oct 12, 2011
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Monroe, NY, USA
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2014 Jetta Sportwagon,2003 Jetta 261K Sold but not forgotten
I always have a milky flow from the pump return to the thermo tee when I do a purge.
I was told it could be from the small injector to injector lines.
When I get time to do another purge I want to replace those hoses and return it to the purge supply.
I also read to pack the thermo tee with petroleum based grease.
 

tacolifestyle

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Mar 16, 2017
Location
Detroit, MI
TDI
2003 Jetta Wagon
New Update:

1. Car is running fine and starts just okay.
2. To recap...I have drilled out the check valve in the sender, cleaned sender, replaced little hoses between injectors with clear tubing, replaced both lines on the engine side of the filter head to clear, all clamps replaced with Oetiker style and pinch clamps on the small lines and a new filter was installed. I also changed the thermo t, the o-rings and banjo bolt washers.
3. I now no noticeable air in the input line from the filter to pump.
4. I do now get a large series of many small bubbles, after about 10-15 minutes, emerging from the pump side of the return line that gather near the thermo tee.
5. At restart, depending on the position of the thermo t valve, the input line can send air mixing into the incoming fuel through the filter. This results in audible stumbling and often smoke out the back.

My question is whether this is most probably the IP seals even when I dont see any leaking of fuel. My gut says that when warm the seals hold then as the pump cools down and the suction of the fuel wanting to return to the tank pulls small amounts of air into that the pump and they gather at the high point near the thermo t.

If it's the seals I can just change those but I could also just eliminate the thermo-t right? I'd like to retain it as I live in a cold climate and travel to even colder climates. Thoughts?
 

UhOh

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2000 & 2003 Golf GLS (2005 Mercedes E320 CDI)
Small bubbles from the return lines is normal.

5. At restart, depending on the position of the thermo t valve, the input line can send air mixing into the incoming fuel through the filter. This results in audible stumbling and often smoke out the back.

Are you saying that you can affect the behavior by moving around the thermo-T?

My question is whether this is most probably the IP seals even when I dont see any leaking of fuel.

Air molecules are smaller than fuel molecules in which case air will find the "holes" before fuel does.

Given your note #5 I don't think that we need to jump straight to this being an IP problem, yet.
 

tacolifestyle

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Detroit, MI
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2003 Jetta Wagon
My thought is that when the Tee is in cold mode it is open to the filter head and closed to the return line. That might not be the case entirely. It may be that it is open to both the filter head and the return line. Either way when the small bubbles have gathered over night at the highest point being the Tee area they condense into one large bubble. Upon start-up, fuel is pushed from the IP return outlet towards the Tee. This in turn pushes any air gathered there into the filter head which is then sucked into the input of the IP. This causes some start-up stumbles depending on how much air is present. I have witnessed this due to both lines now being clear.

The idea that air can infiltrate the IP but fuel does not escape due to their individual physical properties does make a lot of sense. However, shouldn't the seals be air-tight as well and the presence of any air is only an early sign of pending failure of the scale fuel will soon likely be leaking?
 

UhOh

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Dec 24, 2014
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Well, if you don't get the fittings on these CAT filters tight you're going to get leaks. Nothing wrong with them. I have the luxury, living here in the PNW, of being able to ditch the thermo-T, in which case I get a bigger benefit.

I had some difficulties with one of these filters on one of my cars. Took me several attempts to nix an air leak. I was afraid of over-torquing the fittings; found that I had not gotten them tight enough. Also found that one of the original line clamps just wasn't clamping well- replaced with a worm clamp (cause that's what I had on-hand). Issues gone. Now I'll have no further concerns of letting the air Genie back in for mega miles.;)
 

tacolifestyle

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Mar 16, 2017
Location
Detroit, MI
TDI
2003 Jetta Wagon
Yes. There were issues with air getting into the filter due to seals earlier. Those have been resolved in my opinion. That issue only emerged in extremely cold weather after 290,000 miles of no issues with this filter system. You may have missed that I can, due to the clear lines, visually see the bubbles emerging from the pump return and gathering at the thermo-tee. My only assumption is the return suction of the fuel trying to drain back to the tank is pulling air in through somewhere beyond where I can see at the IP return nipple.
 
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