Frustrated...so close, yet so far..air in the lines...

[Vohaul]

Hoping someone can help me sort this out...as im really frustrated, as its so close to being my daily driver again....I havent been on in awhile..as its been sitting

bit of history:
Owned my 93 td jetta (aaz) for 5 years....last year, it started having issues where it would start, then 30 seconds later, stall, restart , then stall 30 seconds later...then finally "clear its throat" or something and drive the whole hour commute home with no issues..any way..soon after the crank pulley blew off on the highway..and i towed and parked it..

so, since i cant seem to let the thing go, i've now...replaced the crank pulley and all belts, also threw on a clutch pulley and replaced all the glowplugs, and retimed it to factory specs (all parts thanks to peiople on this board)..so i fire it up and now this is where i sit...

it turns over and fires up....idles forever...unless i have the cold start on..or rev the engine...then, upon inspection, (after reving or increasing idle.) i get lots of air going in the line to the injection pump..which then stalls the motor...and oddly, after stalling, all the leftover fuel etc.. seems to get sucked back towards the filter..

so heres what i did so far...put diesel conditioner (removes water etc. from the fuel) replaced all the clamps on the inlet and outlet of the fuel filter.(the filter was new)..sillconed the filter inlet and outlets....(just in case)
so i try it out last night...drove through the side streets...it complained a bit with low response from throttle...got to a highway..and let it rip..suddlently it clears its throat and its fine...drove it for an hour on the highway (lots of power etc.)...not a hiccup....look under the hood after when it was idling...no air in the lines....go back on lower speeds again...no issues

tried 2 hours later for another drive....again, no problems...another 30 min drive...

so here i am now, this am..go to start it...no problems..but it died 3o seconds after starting and there was air in the lines again....gave up and took another vehicle to work....

does anyone have any ideas??..i really like the jetta and the diesel as its been good to me....but reliability is a needed factor for me...


Thanks

Paul

[vanbcguy]

Sounds like you've got a plugged or restricted fuel supply.

How old is your filter?

Assuming the filter is fresh, next best step would be to pull the pickup from the tank (you can do this via an access hatch in the trunk).  The "sock" filter in there can get plugged up over time, in particular if you manage to get a biological "infection" in your tank.

[Vohaul]

Sounds like you've got a plugged or restricted fuel supply.

How old is your filter?

Assuming the filter is fresh, next best step would be to pull the pickup from the tank (you can do this via an access hatch in the trunk).  The "sock" filter in there can get plugged up over time, in particular if you manage to get a biological "infection" in your tank.

the filter was brand new last year just before the pulley blew off...do i need a new "sock"...or do you just clean it out?

[vanbcguy]

Inspect it first, go from there. If it is plugged with goop then there's a good chance your tank needs to be cleaned out too.

Other possibilities include a plugged check valve if your car has one, or a crushed / kinked line under the car.

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[burn_your_money]

Other possibilities include a plugged check valve if your car has one,

This was my first thought after fuel filter. I think you can access it by removing the round panel in the trunk with 3 Philips screws.

You can try taking both the in and the out and put them in a jug of diesel. Make sure both lines are submerged. Run the car for a bit to get the air out, and then let it sit and see if the pump loses prime overnight.

Part of your problem is because your fuel system is not self priming until the fuel gets up to temp. This is the biggest drawback of the thermostat tee thing in the fuel filter. Bypassing it is an ok temporary solution if you want to wait for warmer weather to work on it. You'll still get hard starts but at least it should clear up quickly.

[Vohaul]

Other possibilities include a plugged check valve if your car has one,

This was my first thought after fuel filter. I think you can access it by removing the round panel in the trunk with 3 Philips screws.

You can try taking both the in and the out and put them in a jug of diesel. Make sure both lines are submerged. Run the car for a bit to get the air out, and then let it sit and see if the pump loses prime overnight.

Part of your problem is because your fuel system is not self priming until the fuel gets up to temp. This is the biggest drawback of the thermostat tee thing in the fuel filter. Bypassing it is an ok temporary solution if you want to wait for warmer weather to work on it. You'll still get hard starts but at least it should clear up quickly.

ok, so excuse my ignorance, as ive never really gone into this part of the car before

i got the cover plate off...i see a big plastic "ring" inside of which are the fuel lines and the sending unit im guessing..is that ring supposed to unscrew..(mine doesnt move...even after using block and hammer to try and break it loose....)  im assuming under this is the screen and pickup....

so why would the self priming work before and not now?...\\

and do i have a check valve...lol....

[Vohaul]

Update..... Got the whole pickup out of the tank.... Here's a pic....opinions?

[745 turbogreasel]

You should be able to blow through it pretty easy I think.

[burn_your_money]

The check valves are about 6-8" from the fuel sender connections towards the front of the car. They don't look like much, mainly like a piece used to connect 2 different pieces of the fuel lines together.

I've never tried blowing through the fuel pickup/sender but I would imagine it would be easy to do.

[ORCoaster]

With the gooey green stuff showing on the picture on the right I would be inclined to think plugged valve farther down the line.  Check the check valve and now that you have that sender off run some air backwards into the tank down the fuel lines.  If there is a plug in there now is the time to get it out.

[Vohaul]

Ok... Update.... Got the check valve on the feed side off.... To me it seems to have a lot of resistance to me blowing through it.... How easy should it be to blow through?...

And where can I get a new one? ... vw only part? Common?..

Edit: ive been doing some reading ..and do i even really need it?






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[Vohaul]

With the gooey green stuff showing on the picture on the right I would be inclined to think plugged valve farther down the line.  Check the check valve and now that you have that sender off run some air backwards into the tank down the fuel lines.  If there is a plug in there now is the time to get it out.

So you mean blow air down the lines towards the front or injection pump... Or pull the lines  at the filter up front and blow towards the back?


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[ORCoaster]

Pull lines off at the filter and blow back towards the tank. 

[fatmobile]

Since it runs fine once it's going;
 I suspect the small lines between the injectors are letting air in so fuel can syphen back to the tank while it's sitting.
 Also could be the "T" on the fuel filter like someone already mentioned.

[Vohaul]

Since it runs fine once it's going;
 I suspect the small lines between the injectors are letting air in so fuel can syphen back to the tank while it's sitting.
 Also could be the "T" on the fuel filter like someone already mentioned.

Its alive.....i swapped the valve in the tank with a hose barb for now....runs and idles great...it takes a bit to start when cold..so ill probably still get the new check valve for the tank....
but thanks to all that helped out....