ALH air in fuel lines after sitting overnight

[Herm TDI]

Hello people,

So here’s the deal, I had an issue with my Jetta sputtering a bit when started after sitting overnight, after researching and discovering the thermo T issue, I decided to change over to a CAT filter on a Wix base. While I was at it I replaced the rubber fuel lines from the hard line to filter, from filter to IP, and the return from the IP to the return hard line. Also the injector return lines. Well, the problem persists, one way or another air is getting in the lines and causing rough starts and rough idle for a several seconds till it works the air out of the system. Where do I go from here?
I even tried a whole new filter and new base as well, with no change.
I also removed the filter and base (assembled) and pressure tested it but couldn’t find any leaks.

Any ideas appreciated.
Thanks

On the injection pump body there is a fuel shut-off solenoid. The solenoid has an o-ring. Yours is likely dried out brittle and leaking air into the system.

 

[J_dude]

On the injection pump body there is a fuel shut-off solenoid. The solenoid has an o-ring. Yours is likely dried out brittle and leaking air into the system.

Thanks, I have since verified air intrusion is not the issue (at least, not anymore).
Good tip for anyone else looking at this thread down the road though.

 

[J_dude]

Take an 001-004 log i guess? Did you set pump timing down where I suggest? Halfway from red to blue?

Also could take 004 only log, just note try coolant temp

What are your injector balance readings in measuring block 13?

Guess I'll do this tomorrow, in the middle of injectors on the truck today.

 

[ts888]

Thanks, I have since verified air intrusion is not the issue (at least, not anymore).
Good tip for anyone else looking at this thread down the road though.

I should check this. I get a bubble in the clear line when the car sits overnight. Doesn't affect starting or running, but it still bugs me...

 

[wonneber]

I had the same bubble.
I think it's normal.

 

[P2B]

I should check this. I get a bubble in the clear line when the car sits overnight.

Never met an ALH that doesn't. 1/4 - 3/8"

 

[Prairieview]

Soon, only criminals will have air bubbles.

This whole things reads like an old woman's soap opera.

I have a fleet of older 1.6's and ALH's in constant service. When I acquire or put together any of these, I literally toss the "clear" lines and sub-in black rubber lines from O'reilly's, etc. I reseal the pumps and also TOSS the re-cirulating fuel filters and "T" fittings. I keep good 1/8 inch black plastic line between the injectors (bleed-off) and I am NEVER walking or wimping around trying to get one started in cold or hot weather.

A simple life.....is a good life.

 

[J_dude]

I... TOSS the re-cirulating fuel filters and "T" fittings.

What filter do you run?

 

[fatmobile]

On the injection pump body there is a fuel shut-off solenoid. The solenoid has an o-ring. Yours is likely dried out brittle and leaking air into the system.

Isn't that under pressure?
When it opens it allows fuel from inside the pump, which is at over 35psi even at idle, to go to the injectors.
If so you would see fuel leak out instead of pulling air in.

 

[J_dude]

What are your injector balance readings in measuring block 13?

All within spec, not too bad really.

Also, changing the pump did seem to improve the cold start, still not perfect but it's better. I think I'm just going to order some injectors...