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Author Topic: 1.6td won't draw fuel  (Read 432 times)

July 10, 2018, 12:58:47 pm

oblique

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1.6td won't draw fuel
« on: July 10, 2018, 12:58:47 pm »
So more fueling trouble with my mk1 Jetta...same time last year I replaced the pump with a Giles unit because the fuel pump inside the IP was shot.

Car runs fine for about 1o or 20 seconds then starts to lose power, throttle position does nothing. After a bunch of cranking the car will restart and the process begins anew.

Also with a full tank I had a lot of diesel dripping out of the vent drain under the car. Not sure if this is related or if its just expansion.

Anyway I blew out the supply and return lines with shop air and they were clear. Both the return and supply nipples at the fuel tank gushed diesel with no sign of blockage.

Swapped fuel filter and filled it up. Used mighty vac to prime and car will start and run from what seems like the fuel inside the filter and then sputter out because after I'll remove the fuel filter and down to 1/3. Next I tried to prime the pump and basically I drew all the diesel out of the fuel filter and after that I could not get any fuel out of the tank despite confirming the hard supply lines were clear (did not check the rubber line from behind engine to fuel filter but does this clog up?)

What are the possibilities?



Reply #1July 10, 2018, 10:14:19 pm

rabbid79

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Re: 1.6td won't draw fuel
« Reply #1 on: July 10, 2018, 10:14:19 pm »
Just to attribute the problem squarely to the IP or to the fuel tank/lines/filter, I'd run fresh clean diesel fuel straight out of and back into a mason jar.  See if it keeps running ok.  If it does, then move the mason jar lower toward the ground to see if the IP has any problems drawing fuel up a few feet.  If that all checks out, then go after the tank/lines/filter.  Not a lot of fun playing in diesel fuel, but at least you'll have a pretty good idea of where the problem is.
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Reply #2July 10, 2018, 11:14:32 pm

ORCoaster

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Re: 1.6td won't draw fuel
« Reply #2 on: July 10, 2018, 11:14:32 pm »
(did not check the rubber line from behind engine to fuel filter but does this clog up?)

What are the possibilities?

Someone had that man a cubby doll, or a beer.  If you didn't try running the pump on a bottle or jar eliminating the tank and normal fuel system then I would bet a dollar to a doughnut, I love those things, that you have a gummed up rubber line.  That is where I have seen most of the gubbers collect. 

Pull that line off and verify it is clear.  Look at the banjo fittings as well.  Sometimes they get a ring of junk in them. 

It sure sounds to me that you are just developing a vacuum on the line and starving the pump for fuel.  A jar with a line for fuel in to the IP and one out of the OUT bolt back to the same jar should get all those issues out of the way.  Then you can figure out if you have a leak in seals and loosing ability to draw fuel in or see air being put into the system from seals going bad.

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Reply #3July 11, 2018, 10:00:55 pm

oblique

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Re: 1.6td won't draw fuel
« Reply #3 on: July 11, 2018, 10:00:55 pm »
Thanks for replies!

I am losing sleep that Ive ruined another pump because I cannot afford to replace and that would mean putting the car to sleep.

I will check that upper rubber line. Also how do I blow air through banjo fittings? I want to check the fuel filter bracket.

Is this upper rubber line still available for purchase? I cannto find it anywhere. Also do I have to make my own fuel filter > IP supply line if I want a clear one?

Reply #4July 11, 2018, 11:14:17 pm

ORCoaster

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Re: 1.6td won't draw fuel
« Reply #4 on: July 11, 2018, 11:14:17 pm »
Oblique no need to loose sleep on this.  That is for Obtuse to do that.

I don't think you have ruined another pump.  A plugged line or filter just puts a vacuum on the system and it stops the car after awhile.  No fuel delivered, no engine rotation.  Sorta simple there.

I have had a hard time getting that line off the metal line in the past.  I think I even ended up just cutting off the end and then cutting down the metal line to get the piece off.  That stuff is like iron once it sits there for that many years. 
I don't know that you can do anything other than blow air back into an open line connected to the banjo fitting.  Again it might be necessary to cut it off.  I do a visual inspection holding it up to the sun to see an open hole. 
I would caution you on the filter bracket as well, Those things also are solid on there.  The 17 mm nuts get tight for whatever reason and they are in a position that assures your knuckles are going to be bloody if the wrench slips.  So be prepared and wear some gloves.

I think the line going into the filter is standard 1/4 or 7 mm metric.  Just get a new piece from your local auto store and be sure it is fuel rated not some goofey stuff from the hardware section or Home Depot.  I know, people have used it and claim all sorts of great things.  But face it, it is a critical piece of the fuel system.  Not something you want to have crack on you in the dark of the night years from now on a deserted highway, with no cell connection. 

Some have installed one of those lawnmower type fuel filters before the pump as those are clear and about the same diameter line.  There are even ones with glass outer shells that have a replaceable filter inside.  A little more cash for them than the prior one.

Good luck. 
Now Own 1981 Caddy as the NEW DISTRACTION to all that is around me.  Project Away!

Reply #5July 13, 2018, 10:25:17 pm

oblique

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Re: 1.6td won't draw fuel
« Reply #5 on: July 13, 2018, 10:25:17 pm »
Arggghh so everything is lined to replace all rubber fuel hoses tomorrow but I didnt realize the upper supply hose is pressed on from the factory..is there a barb on the inside when its pressed on?

The new part has the barb fitting I need and is 3-5 days wait from my local dealer and this is it:

https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/banjo-fitting/n90254601/

Banjo bolt is 14x1.5

Reply #6July 13, 2018, 10:56:41 pm

ORCoaster

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Re: 1.6td won't draw fuel
« Reply #6 on: July 13, 2018, 10:56:41 pm »
Holy Smoke, for the price of that Banjo bolt I could have sent you 10 that I have laying around here. 

Yes the barbed fitting is what makes it so tough to get the old line off.  So just cut it down the length of the barbs and get it to loosen up that way.  Many times I use a pair of wire cutters and clip the fuel line, remove the fitting and then handle the removal in a vise so I am not slicing up my fingers.  Already did that years ago on a tablesaw, so a few don't work so great now.  Trying to keep the point of a Stanley knife on the rounded surface and pull down the length is not always going to happen smoothly.  That is why I vice the fitting and keep clear of the blade.


If you have all new lines to install cutting the old ones off isn't a bad thing.  Some folks claim soaking them in very hot water makes them come off but I have never tried that. 
Now Own 1981 Caddy as the NEW DISTRACTION to all that is around me.  Project Away!

Reply #7July 15, 2018, 09:19:17 pm

oblique

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Re: 1.6td won't draw fuel
« Reply #7 on: July 15, 2018, 09:19:17 pm »
Well..she's running. After replacing all the lines I decided to remove the fuel filter housing and found a series of gouges and sharp edges sticking up on the sealing surface. Cleaned those up and smoothed the low spots as best as I could and put the filter on real tight and mo issues after 500km.

One question though...There was no 3/16" fuel line available so I bought 7/32 vacuum hose for to connect filter to IP...is this ok? Its a thick rubber hose but is not reinforced and not sold as a 'fuel' specific tubing.

Reply #8July 15, 2018, 10:49:07 pm

ORCoaster

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Re: 1.6td won't draw fuel
« Reply #8 on: July 15, 2018, 10:49:07 pm »
I would be asking the parts guy to let you know when they get some 3/16 fuel line in.  Diesel on vac hoses doesn't do them any good.  Slowly softens them up and you will be having air problems again.  Your time will run out, and you will be fist shaking the car again. 

Just plan on replacing that couple of feet with something meant to do the job once and for all.  But for now it will work. 
Now Own 1981 Caddy as the NEW DISTRACTION to all that is around me.  Project Away!

Reply #9July 18, 2018, 06:02:36 pm

oblique

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Re: 1.6td won't draw fuel
« Reply #9 on: July 18, 2018, 06:02:36 pm »
So is PVC the way to go for clear diesel lines? How restrictive is a 3/16" (4.5mm) line vs the stock 7/32 (5.5mm) diameter?

On a side question, whats with the tapered hose from tank to supply line? Is it just to use the same tank for bigger engines? Flow? https://www.ecstuning.com/b-genuine-volkswagen-audi-parts/hose/171201543b/

Thanks for all the help btw. I know folks have bigger issues than this on this forum so I appreciate you taking the time.

Reply #10July 18, 2018, 11:43:39 pm

ORCoaster

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Re: 1.6td won't draw fuel
« Reply #10 on: July 18, 2018, 11:43:39 pm »
For clear lines on the IP, both sides, I recommend you go to a motorcycle place and get fuel line from them.  They have the smaller diameters we need.  I wouldn't put PVC on there.  I bet it gets rock hard and will crack from vibration at some point.  Like the darkest, rainiest night of the year.  When you are in Nowheresville and can't get replacement line of any sort.


Not sure why we have that size change from tank to supply?  Might be for uniformity across other VWs. 

All issues big or small entertain and inform.  Hope this  was helpful.
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Reply #11July 21, 2018, 01:51:19 am

fatmobile

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Re: 1.6td won't draw fuel
« Reply #11 on: July 21, 2018, 01:51:19 am »
1/4" line to the pump right?
 Not 3/16".
 Even clear vinyl works great.
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Reply #12July 25, 2018, 11:27:32 pm

oblique

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Re: 1.6td won't draw fuel
« Reply #12 on: July 25, 2018, 11:27:32 pm »
1/4" filter->pump doesnt fit snugly over the barbs because the stock size is 7/32" but the next common size is down 3/16", unfortunately. I've read some people run 3/16 ok?

Reply #13July 27, 2018, 03:27:17 am

libbydiesel

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Re: 1.6td won't draw fuel
« Reply #13 on: July 27, 2018, 03:27:17 am »
1/4" ID tubing fits snugly enough on the stock pump inlet banjo fitting that I don't typically even clamp it when I use the thick wall tygothane. 
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