Lots of air in fuel line on start up?

[thedart]

Recently my girlfriends 89 turbo diesel Jetta was taken to the shop to have the fuel system water separator looked at it was leaking fuel bad. Not having the funds to replace the separator with a new one she had the shop bypass the separator taking it out of the system.
ever since she has had the car back from the shop she has had serious problems starting the car first thing in the morning and getting it to stay running. I had a look and realized that it was being starved of fuel, watching the fuel line from the fuel filter to the injection pump I see lots of air moving towards the pump for quite some time. The car can be limped enough to get it moving and eventually will take off and start to act normal. Once moving along for a while it drives normally and idles just fine, looking at the fuel line it is clear and no air to be seen.
I told her to take it back to the shop and ask if something might have been overlooked. the mechanic said that it was her Injector pump and that it will cost her 1500$ to 1800$ to have it sent away and fixed? This doesn't make any sense to me but I'm no expert. Does this sound right I'm leaning more towards a possible air leak into the system from where they removed the water separator.....Please any help or guidance would be appreciated

[jtanguay]

its possible.  but i suspect the fuel preheater to be leaking air into the system as well.  the in tank pickup could be stuck as well.

[thedart]

Thanks I'll make not of that, phoned another mechanic today explained that there was lots of air in the line, he said that the injector pump would have nothing to do with that. I'll be making an appointment to have it looked at. In the mean time if anyone else has any suggestions or experienc with this problem feel free to add.

[jtanguay]

Thanks I'll make not of that, phoned another mechanic today explained that there was lots of air in the line, he said that the injector pump would have nothing to do with that. I'll be making an appointment to have it looked at. In the mean time if anyone else has any suggestions or experienc with this problem feel free to add.

and he's right because while the injection pump can suck in air, the fuel inlet hoses should still not have air bubbles.  you will notice a big drop in power/mileage if the pump sucks in enough air though.  it can also cause cavitation and start to pit/rust the inside of the pump.

the fuel lines also tend to crack on the insides and its a good idea to cut off the ends until you don't see cracks.  air can seep in overnight this way, and then bleed out after being started up and running for a few seconds. just tightening the clamps won't really remedy this problem.

[fatmobile]

Check the in-tank screen to make sure it isn't clogged and restricting the fuel line.
 
 They might have removed the check valve along with the water seperator,.. good idea to remove that instead of replacing it.
 If they did; any leak, even leaks oround the little lines between the injectors can let air in while fuel syphens back to the tank.

 The mainshaft seal on the injection pump can let air in if it's bad. You might not see alot of fuel around it but if you rub your finger behind the sprocket, near the shaft, you might come back with some diesel on your finger. A clear line coming out of the pump will often show air/foam in the fuel leaving the pump and heading back to the tank.

[Smokey Eddy]

 They might have removed the check valve along with the water seperator,.. good idea to remove that instead of replacing it.

I didn't even know you COULD replace it... it is after all useless...

[thedart]

Ok well car is back from the shop the day I droped it off I had the same symptoms on start up and when I tried to drive the car at first. I limped through the rough running phase then it drove fine to the shop. I explained everything that I had been experiencing and left it over night at the shop to be looked at the next day. I get a phone call the next day from the mechanic telling me everything is working fine on the car? he can't get it to act funny at all. Now at this time I'm really confused he also mentioned that all the glow plugs were just fine which I was told from the other that I needed three new ones? I could explain why it wasn't acting funny on start up like it had been. Well I got a new fuel filter and replaced some lines that were questionable and the car has been running just fine ever since I picked it up. We did get to talking about a serious water leak that we have been having trouble with in the car, where water has been leaking almost directly on the fuse box under the dash during heavy rains. After mentioning this to the mechanic he said this could very well be what was causing the problem? something about interrupting the signal to the injection pump. Since then I have been tarping the hood and front window keeping it dry untill I can locate the leak and things seem to be running fine.

[diesel smoke]

the only signal the pump is getting is through the accelerator through a braded steel cable. No electrics involved whatsoever except for the solenoid, but if the car runs at all, it's good.

[8v-of-fury]

they must have fudged something up when they were toolin with your lines in the back.. If there was no air before and there is air now.. then it was there fault

Seems like you have a leak somewhere in the fuel lines that is allowing it to drain the injection pump.. meaning you are practically priming it every start-up. not fully of course.. but that's what i believe it is

[Rabbit TD]

Ok well car is back from the shop the day I droped it off I had the same symptoms on start up and when I tried to drive the car at first. I limped through the rough running phase then it drove fine to the shop. I explained everything that I had been experiencing and left it over night at the shop to be looked at the next day. I get a phone call the next day from the mechanic telling me everything is working fine on the car? he can't get it to act funny at all. Now at this time I'm really confused he also mentioned that all the glow plugs were just fine which I was told from the other that I needed three new ones? I could explain why it wasn't acting funny on start up like it had been. Well I got a new fuel filter and replaced some lines that were questionable and the car has been running just fine ever since I picked it up. We did get to talking about a serious water leak that we have been having trouble with in the car, where water has been leaking almost directly on the fuse box under the dash during heavy rains. After mentioning this to the mechanic he said this could very well be what was causing the problem? something about interrupting the signal to the injection pump. Since then I have been tarping the hood and front window keeping it dry untill I can locate the leak and things seem to be running fine.

I'm not going to get into your fuel problem because I am having similar symptoms myself in my Rabbit.  But I would almost guarantee that your waterleak is the windshield gasket.  They do this on Rabbits all the time and drip right on the fuse box like your's is doing.  It can really cause some odd things to happen to the relays especially.  You can get a tube of windshield molding sealer almost anywhere and it will seal it fine.

[burn_your_money]

The rain gutter drains could also be plugged up.

The air in the line after the repair could be unrelated to the repair. Old cars always seem to have multiple things go wrong at the same time, or one after the other. I have a theory that when you put a new part on a car, another part gets jealous and starts acting up, so you have to replace that one, and so on. I usually just try not to disturb the sensitive vw ecosystem under my hood.

[Jettage1]

The rain gutter drains could also be plugged up.

The air in the line after the repair could be unrelated to the repair. Old cars always seem to have multiple things go wrong at the same time, or one after the other. I have a theory that when you put a new part on a car, another part gets jealous and starts acting up, so you have to replace that one, and so on. I usually just try not to disturb the sensitive vw ecosystem under my hood.

I like Tyler's theory...  OT, but an old fellow gearhead friend of mine used to say that you could either bust your knuckles fixing the car, or just burn a small pile of money in front of the car...  Either method might have the same effect of appeasing the little tin god on four wheels...  Fits your username, too, Tyler!
Sorry for the diversion-couldn't resist.