IP Pumping/sucking air? both a 16n/a and 1.6TD

[btrapr]

I have a '81 1.6 N/A that I pulled the pump off of a parts car that ran great and put on another motor. The motor runs but has air in the line. I have gone out to start this one and saw no air at start-up then as it warms you see the air build, other times it has air from start-up. You can see that air in the last section from fitler to pump, and as you run the RPM's up and the pump draws in more fuel...YOU can watch the air pockets lengthen? NEW fuel filter- screw on type!
I replaced the small section of supply/return ruuber lines at the tank the rest looks good..

Believe it or not I have a '85 1.6 Turbo diesel with enrichment circuit...I had the pump rebuilt pump and replaced it and it too is doing the same thing. fuel lines look good? This vehicle starts and runs but will crap out from lack of fuel...NEW fuel filter can

I am baffled_____I had heard that on the pump the return spigget where the injector return line and tank return line has a small screen and micro port/hole in where the banjo bubbles out and that if either gets plugged or restricted can casue this? Can the timing being off a little cause this? they both start fine and I have tweaked the timing on both a hair either way to see if it improves and is does not. Really strange that both are doing it and the TD craps out? Perhaps I am lacking the skills BUT I am baffled and frustrated. ON both I changed the last section of line from filter to IP to see if it made a difference and it doe not. What am I doing or not doing that has casued this?

PLEASE help

I there a strainer in the tanks? wondering if algae could be causing this issue as both vehicles sat for awhile? I will try a can of fuel with in-line filter to see if it goes away.

[Quantum-man]

If air appears in the clear line from filter to pump whilst running then air is coming in somwhere on fuel filter or nearer to the fuel tank.

If air appears after stopping, and clear line drains, then air leak is in pump.

[82vdub]

Yes, there is a strainer in the tank and if that's plugged, it will allow air to come in from just about any fitting. Also, since air can come in just about any fitting, it's time to start chasing fuel line from the filter back to the tank and check the condition of any fittings or rubber line. Even if you think the fittings on the filter are good, some have found that they still leak (easy to happen if you have the cheap clear vinyl line on it) and can leak around the air bleed screw on the top. Don't forget the rubber lines that go from the body of the vehicle to the lines in the tank.

[btrapr]

thanks for the info! just needed outside input in case I was missing something simple. I am still elarning these vehicle. I left older Mercedes behind to get a little better mileage.

[Fatmobile]

'85 Jetta?
Does it still have the water seperator under the car?
There is also a check valve near it that can restrict fuel flow.

Classic fuel line restriction symptom of elongated or increased bubbles when revved.
I don't think air in the lines means there is a leak letting air in,
Fuel line restrictions cause a vacuum that expands and clumps any disolved air.
It's like pulling fluid into a syringe, pull the plunger fast and half the volume will seem to be air, when it equalises no air is visible.

You also need to check the pickup screen in the tank.

A vacuum gauge on the fuel line will warn you of fuel line restriction way before it's a problem.

[btrapr]

how do you get to the filter screen in the tank?

I took the water seperator out because the lid was leaking! bypassed with hose
thanks again

[Fatmobile]

There's a check valve near it that you should remove as well.

The fuel level sender is in the trunk, far right, rear corner.
You should have a vacuum cleaner handy because once you remove the tin cover; the sender will be surrounded with crap that settled on top of the tank.

[btrapr]

Fatmobile___
thank you so much I am going outside in a minute to look at those two things! check valve and sender.

[btrapr]

ONE down and one to go!

First i pulled the return outlet on the pump and checked the orifice on the banjo- it looked good and no restriction. Then I blew a little air down the return line and heard bubbles in the tank. Then I pulled the fuel supply line at the tank no the Rabbit truck and only a trickle of fuel came out...Hit it with an air hose (I know not the proper way) and hit it. The fuel started pouring out, dang near got a bath before I could get the hose back on. I have not driven it yet, but I suspect it is fixed at least unitl/if it plugs up again! I also blew out the vent line.

* I almost hope that it blew the screen off! I want to put a Mercedes clear plastic type in line filter in it, that way I can use brake fluid and clean it out if it plugs on the raod. I know that works because I had an old Mercedes that had a real algae problem! that is what I did after draining the tank and replacing all of the filters...It cleared itself after a couple of tanks of fresh fuel. I would advise against putting a algicide in th tank because they usally cause the algae to die and fall out causing large clumps of muck to deal with, do not ask how I know. DRAIN THE TANK, CHANGE FILTERS, PUT AN INLINE CLEAR FILTER IN THAT CAN BE CLEARED OR REPLACED ON THE SIDE OF THE RAOD UNTIL IT CLEARS ITSELF OUT.

I still need to take another look at the jetta, well maybe tomorrow

thanks again for the hints and opinions!

[bottleworks]

Are you the one on Craigslist asking about a VW mechanic in the area?

[btrapr]

not, I have posted.