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Author Topic: Help with a 1997 jetta with a AAZ (hard starting and wiring)  (Read 556 times)

April 16, 2019, 12:59:21 am

Phaeton

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Help with a 1997 jetta with a AAZ (hard starting and wiring)
« on: April 16, 2019, 12:59:21 am »
Hello everyone!
I'm new when it comes to diesels, and I've recently acquired a Canadian 1997 Jetta with a AAZ motor. Unfortunately there has been some tomfoolery in the wiring. Most of the relays have been pulled out of the panel, fuel delivery pump is outright missing (thought it was a in tank unit but its not) and a ground for what i believe is relay 109 was burnt up... Very strange stuff! But more to come! I temporary fixed relay 109, jumped my fuel cut off solenoid (because it was only getting 3 volts with and without the relay) and added a aftermarket electric fuel delivery pump, and got it to fire after tons of cranking and black/white smoke. I took out my glow plugs to test to see if they work, They did. So i cleaned up the connection points and my bus bar because it was heavily corroded and am going to try tomorrow. The car shows 114,xxx km. Is there any other reason why this car would start so hard? Its about 3-10 degrees C. While i was waiting for some parts to come in i put my car on a lift to trace the fuel lines to try to find the oem fuel pump, thinking it was a inline pump. Still couldn't find it. I took out the carpet in the trunk and found the sending unit with no in tank pump. I found the wires to the sending unit have also been stripped about 1/4 inch and the sending unit unplugged. Very sketchy. later found out my fuel gauge isn't working :( the sending unit tested somewhere between 36ish to 250ish ohms, depending where the float is.

Anyone have a diagram of my relay/fuse panel and what relays i need? Turns out my 1997 AAZ Canadian car is very different than other cars, so finding my specific relay location is challenging. And where is my stock fuel pump location? I cant find unplugged wires anywhere. Is my fuel gauge linked to relay 109? i'll get some pictures tomorrow aswell for anyone interested! Sorry for the wall of text  :P



Reply #1April 16, 2019, 12:01:28 pm

libbydiesel

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Re: Help with a 1997 jetta with a AAZ (hard starting and wiring)
« Reply #1 on: April 16, 2019, 12:01:28 pm »
I do not believe the AAZ has any fuel pump other than the injection pump on the engine.  The injection pump serves double duty for both pulling the fuel from the tank and pushing it through the injectors and into the engine.  Adding a lift pump can sometimes help, although that help is often in the form of covering up other issues, and without a lift pump the engine should start and run fine.  There are a slew of reasons that can cause hard starting.  Here's a non-exhaustive list:  injection pump lost its prime, fuel filter lost its prime, poor injection pump timing, poor cam timing, mediocre battery or connections, mediocre starter or connections, bad glow plugs (even one bad one makes a big difference), no current to glow plugs, the simple act of forgetting to pull the cold start, bad lifters, clogged air filter, bad fuel, bad injection pump, etc, etc, etc... 
Use, abuse or ignorance of any information is at your own risk, confirmation or refutation is your own responsibility, no further 'proof' will be given, take it or leave it, YMMV,terms subject to change without notice, avoid contact with eyes or skin, contents known to cause cancer in California

Reply #2April 16, 2019, 03:48:12 pm

Phaeton

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Re: Help with a 1997 jetta with a AAZ (hard starting and wiring)
« Reply #2 on: April 16, 2019, 03:48:12 pm »
I do not believe the AAZ has any fuel pump other than the injection pump on the engine.  The injection pump serves double duty for both pulling the fuel from the tank and pushing it through the injectors and into the engine.  Adding a lift pump can sometimes help, although that help is often in the form of covering up other issues, and without a lift pump the engine should start and run fine.  There are a slew of reasons that can cause hard starting.  Here's a non-exhaustive list:  injection pump lost its prime, fuel filter lost its prime, poor injection pump timing, poor cam timing, mediocre battery or connections, mediocre starter or connections, bad glow plugs (even one bad one makes a big difference), no current to glow plugs, the simple act of forgetting to pull the cold start, bad lifters, clogged air filter, bad fuel, bad injection pump, etc, etc, etc...

Thanks for the input! I'll be making sure the fuel system doesn't have air in it today, and bleeding it out. Glow plug wise i hope my cleanup job makes a difference in starting. If not looks like i'll have to look at timing! I'll run out to my shop and take a few pictures of my relay panel!

Also i think i'm being upgraded from vw newbie to vw super noob. Didn't even realize what that black handle was for ;D Ive only had experience with big old diesel motors and a lincoln mark vii with a 2.4 bmw diesel. Passenger diesels are very new to me.

Reply #3April 16, 2019, 05:39:59 pm

Phaeton

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Re: Help with a 1997 jetta with a AAZ (hard starting and wiring)
« Reply #3 on: April 16, 2019, 05:39:59 pm »
Here are some pictures of my car:


this is my relay panel. I'm pretty sure im missing some relays. Also where i found the burnt wire which i think is a ground? yeah i put tape over the beeper. its annoying  ;D



here is the wire after the connector. Seems find the farther up it goes into the harness but i don't trust it so i ran a new wire.




even with the new ground the wire to my fuel shut off is 3 volts with or without the 109 relay in spot #3




the pin with the burnt wire. connector seems fine however.



all the relays that where rolling around on the floor...  :o Where do they go and what do they do?


Reply #4April 21, 2019, 07:17:13 pm

Phaeton

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Re: Help with a 1997 jetta with a AAZ (hard starting and wiring)
« Reply #4 on: April 21, 2019, 07:17:13 pm »
Fuel sending unit refuses to work  ??? got my fuel gauge to spaz from empty to half then it quit. Any help would really be appreciated! Is one of my relays rolling around on the floor used for the sending unit?

Reply #5April 23, 2019, 07:38:32 pm

libbydiesel

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Re: Help with a 1997 jetta with a AAZ (hard starting and wiring)
« Reply #5 on: April 23, 2019, 07:38:32 pm »
I have not owned a stock AAZ vehicle.  You might want to get the A3 Bentley which includes the wiring diagrams.

If it is still hard starting, the first thing I would do is test for power at the glow plug buss bar on a cold start when the key is turned to ON.  Next I would add clear fuel lines before and after the injection pump and see if the fuel is draining back when it sits. 
Use, abuse or ignorance of any information is at your own risk, confirmation or refutation is your own responsibility, no further 'proof' will be given, take it or leave it, YMMV,terms subject to change without notice, avoid contact with eyes or skin, contents known to cause cancer in California

Reply #6April 24, 2019, 01:32:24 am

Phaeton

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Re: Help with a 1997 jetta with a AAZ (hard starting and wiring)
« Reply #6 on: April 24, 2019, 01:32:24 am »
I have not owned a stock AAZ vehicle.  You might want to get the A3 Bentley which includes the wiring diagrams.

If it is still hard starting, the first thing I would do is test for power at the glow plug buss bar on a cold start when the key is turned to ON.  Next I would add clear fuel lines before and after the injection pump and see if the fuel is draining back when it sits.


My buss bar tested good for power, but as i bled my injection pump and injectors the car started up quick without the glowplugs surprisingly. Ran like a clock until it warmed up, then started running rough. No air is in the fuel system. I checked the return line as it is clear, but i disconnected it and let it drain into a bottle to see if any bubbles came out anyway, i don't think there is air in my fuel system now. Would timing be the cause of this?

 

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