Author Topic: 85 Jatta NA - rough smoky start sometimes (Read 4847 times)

BigAndy · « **on:** January 13, 2009, 05:00:55 pm »

Need some confirmation or other ideas:

1985 Jetta 1.6 NA, 300k, reringed 40k ago

Car started great and ran well for several years. Wife takes it to Vancouver and it sits more than normal. She goes to start it and it shakes and smokes. I travel down and replace fuel filter and add some power service. No improvement.

Car is at home now, I have retimed the engine, retimed the pump to 90, removed the water separator, checked the injectors, blew back the fuel lines with my compressor. I can draw fuel fairly easily from the tank. I don't have a vacuum guage hooked up to measure, but I can if warranted. I have also hooked up a separate tank of diesel and ran it straight to the IP bypassing the fuel filter with the same result. Compression on all cylinders is good.

Car will usually start rough, and if left to idle, will calm down into a nice well behaved 1.6. Sometimes it will pull for a minute and behave, but then acts like it's starving for fuel. If I stop and let it idle, it'll smooth out again.

It looks like air bubbles travel back to the filter from the pump after I shut the engine down.

Does this sound like the IP is getting past it's prime (pun intended) and I need to overhaul it or should I try something else? I've seen suggestions to install an electric fuel pump, but this sounds like it's putting off the inevitable.

Dakotakid · « **Reply #1 on:** January 13, 2009, 09:37:18 pm »

It may very well be time to start thinking about replacing the IP front shaft seal. Any idea if it has even been replaced before???

BigAndy · « **Reply #2 on:** January 13, 2009, 11:57:28 pm »

I highly doubt anything has been touched on the IP. I'll search for that repair and size up the job. Thanks for the tip.

fatmobile · « **Reply #3 on:** January 15, 2009, 12:05:11 am »

Yep, if you are bottle feeding it and it still has air bubbles coming out after shutoff, reach down behind the injection pump sprocket and feel for diesel.

Sounds like the injection pump shaft seal decided it was a good time to start leaking.
Small lines between injectors can also let air in.
Did you remove the check valve inn the fuel line?,... you said you blew air back through the lines,... hard to do with a check valve in place.

BigAndy · « **Reply #4 on:** January 16, 2009, 08:42:43 am »

I have looked for diesel all around the pump and there doesn't appear to be any leaking. I removed the water separator -- presume that's where the check valve was?? Air seemed to move pretty quickly through the line, so I presume the checkvalve was removed.

The lines between the injectors are under a year old, but I checked them again. I got a used pump from the local autowrecker ($300....) and will throw that on. I've run out of other ideas other than a worn pump.

I'll report back after I get this 'new to me' pump on.

jtanguay · « **Reply #5 on:** January 16, 2009, 04:59:35 pm »

Quote from: "BigAndy"

I have looked for diesel all around the pump and there doesn't appear to be any leaking. I removed the water separator -- presume that's where the check valve was?? Air seemed to move pretty quickly through the line, so I presume the checkvalve was removed.

The lines between the injectors are under a year old, but I checked them again. I got a used pump from the local autowrecker ($300....) and will throw that on. I've run out of other ideas other than a worn pump.

I'll report back after I get this 'new to me' pump on.

be careful with that "used" pump from the wreckers... if its been sitting for a while it might be junk as well. i would consider it a core unless it was stored with fuel.

burn_your_money · « **Reply #6 on:** January 16, 2009, 07:40:46 pm »

How did you check the injectors?

Next time you shut the car down, clamp off the return line that goes to the injectors with a pair of vise grips or something. If the pump doesn't fill with air and start rough then it's the soft lines that need replacing

BigAndy · « **Reply #7 on:** January 17, 2009, 10:58:15 am »

Good tip. I'll try that before I swap out pumps. I have a pop tester for my injector testing and I have the VW diesel compression guage to test cyl compression.

The pump does get noisy when it's starving for fuel (or cavitating due to air), once it gets fuel, it quiets down and of course it smooths right down, the smoke disappears. On the road, it doesn't take long before it goes into that 'starving' mode. If I stop and let it idle for a bit, it'll calm down again. On the highway, it's constantly surging, smoking, and generally not running well.

And with the 'used' pump -- I told the guy that this is risky and if the pump didn't work, it was coming back. He understood and gave me the ok. Not that it helps me because I get to do all the work...

burn_your_money · « **Reply #8 on:** January 17, 2009, 03:11:33 pm »

Did you bypass the fuel return and feed when you were running it off a bottle or only the feed?

BigAndy · « **Reply #9 on:** January 17, 2009, 04:06:01 pm »

Had both running out of one container. There's lots of room to actually strap a gallon container in and drive.

So here's the update:

installed the 'junker' pump. Bit of a problem with the pump as the belt doesn't track straight on it. Car runs better BUT I did I now see that the head is cracked where #2 injector screws in.

I think all things considered, the head needs to pulled and I'm not going to bother fixing it. I'll part the unit out and go find another project to play with.

burn_your_money · « **Reply #10 on:** January 18, 2009, 07:24:30 am »

My 92 TD had a cracked injector boss. It always worked fine until I crashed the car. Actually it still worked fine and that motor is down in PA somewhere powering someone elses car.

It'll depend how bad the crack is. You will hear a huffing sound and you should see some smoke escaping from the crack if it is critical. If it's not huffing or smoking I would just leave that injector alone