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jung
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Joined: August 11, 2015
Posts: 103
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 Posted: Thu Nov 19, 2015 5:54 pm Post subject: Air-cooled: won't start |
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I have a starting issue on my 82 air cooled vanagon. A starter works and a fuel pump works well but fuel injectors do not shoot any gas. I checked spark plugs and I could see sparks. I checked input voltage on fuel injectors and I found that the voltage is very low for some reason. ( My battery is new and full ) I tested with my light probe and it barely lights the bulb. You can see that orange color in the middle of the attached picture. I guess it is around 1V. It blinks when I try to start.
Does this mean that there is any short? I checked double relay input and it seems to get right input. I followed this instruction to check if double relay is well grounded or not.
http://type2.com/bartnik/dblrly.htm
Please let me know if you have anything that I need to check. Thanks!
Last edited by jung on Fri Nov 27, 2015 6:48 pm; edited 1 time in total |
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djkeev
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fxr
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Joined: December 07, 2014
Posts: 2325
Location: Bay area CA
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| Posted: Thu Nov 19, 2015 7:38 pm Post subject: Re: very low voltage on fuel injectors |
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The injectors only receive a short pulse - your light-bulb tester integrates this out and will only glow very dimly, if at all. Such a tester is good for finding shorts or open circuits in normally constantly powered circuits - not for pulsed systems such as the injectors.
A diode/capacitor together with a voltmeter will help here. A very rough ASCII diagram.  :
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1N4001 | |
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0.1µF ___ Voltmeter
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Jim Crowther
1984 1.9l EJ22 Westy Wolfsburg Edition
Vespa GTS 300 |
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VWCOOL
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Joined: June 02, 2006
Posts: 1821
Location: Down under
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| Posted: Thu Nov 19, 2015 7:43 pm Post subject: Re: very low voltage on fuel injectors |
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| jung wrote: |
I have a starting issue on my 82 air cooled vanagon. A starter works and a fuel pump works well but fuel injectors do not shoot any gas. I checked spark plugs and I could see sparks. I checked input voltage on fuel injectors and I found that the voltage is very low for some reason. ( My battery is new and full ) I tested with my light probe and it barely lights the bulb. You can see that orange color in the middle of the attached picture. I guess it is around 1V. It blinks when I try to start.
Does this mean that there is any short ? I checked double relay input and it seems to get right input. I followed this instruction to check if double relay is well grounded or not.
http://type2.com/bartnik/dblrly.htm
Please let me know if you have anything that I need to check. Thanks !
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As with some other EFI systems, your fuel injector pulse/operating voltage may be 5V, not 12V
Start by checking this voltage against specs...?
Then check the injector earths - they may be 'ganged' together and all be suffering from the one corroded fastener |
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jung
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Joined: August 11, 2015
Posts: 103
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| Posted: Thu Nov 19, 2015 8:17 pm Post subject: Re: very low voltage on fuel injectors |
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I have tested fuel injector resistance which is about 3 ohms but I couldn't find the appropriate voltage for it. Actually I tested 5V on the light probe and it is much brighter than I see. So I assume that the voltage is about 1V~2V. Like it is suggested that light probe is not a good idea to test this when the voltage fluctuate rapidly. One fuel injector is unscrewed so it will spit out fuel when it is fixed. Currently no fuel out from injector.
There a few mysterious things in my engine compartment although I could not find the fuel injector ground.
This is one ground that I found on driver side of engine compartment. A strange thing is that there are two screws on the wall and a broken plastic piece is attached on both screws. ( One is gone in the picure when I check ground ) I wonder if I'm missing a plastic part. I have no idea one what was there before.
I also found a disconnected socket between intake manifold of cylinder 1 & 2. It has 3 pins in it. It is dusty so I assume that it has been disconnected a while. I could not find a right place to connect this.
I have no history on this vehicle. The previous owner abandoned and I'm trying to give a life back. Thanks for all advices ! |
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jung
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Joined: August 11, 2015
Posts: 103
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| Posted: Thu Nov 19, 2015 8:22 pm Post subject: Re: very low voltage on fuel injectors |
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It seems like the ground that I found near the coil is for oxygen censor and fuel pump relay.
"Check the ground connection near the coil, on the left side of the
engine compartment. This is also the ground for the oxygen sensor and
the fuel pump relay."
The info is from here.
http://gerry.vanagon.com/files/technical/digifant-diagnosis-checks.txt |
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jung
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Joined: August 11, 2015
Posts: 103
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| Posted: Thu Nov 19, 2015 9:56 pm Post subject: Re: very low voltage on fuel injectors |
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Maybe what I'm missing in my 82 vanagon is the white object in the middle. I found this picture from gallery. I have only black broken plastic pieces on two screws. Does anyone know what that is ?
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Wildthings
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Posts: 50353
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| Posted: Thu Nov 19, 2015 10:00 pm Post subject: Re: very low voltage on fuel injectors |
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| Checked your fuel pressure yet? Does your fuel pump run when you hold the door in the AFM open with the key on? |
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chompy
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Location: Cascade Locks
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| Posted: Fri Nov 20, 2015 9:48 am Post subject: Re: very low voltage on fuel injectors |
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| jung wrote: |
Maybe what I'm missing in my 82 vanagon is the white object in the middle. I found this picture from gallery. I have only black broken plastic pieces on two screws. Does anyone know what that is ?
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That's just the idle stabilizer, which is a California spec item, and can be unplugged or cleaned. Apparently the PO just removed it. Like Wildthings said, you need to be sure the fuel pump is turning on when the ignition is turned over. You can lay near the fuel pump while someone else cranks the engine and you should hear it turn on, or push on the vain in the AFM with the key on, and you should hear it click on and off.
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MarkWard
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Joined: February 09, 2005
Posts: 17155
Location: Retired South Florida
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| Posted: Fri Nov 20, 2015 10:15 am Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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Hello, I am sure someone will correct me, but on the AFC injection system. The ECU completes the ground to fire the injector. They get power from the Double Relay. There should be an inline resistor pack screwed to the front of the engine compartment. Look in this picture. Top left.
It reduces the voltage to the injectors down from 12 volts.
So, you should be checking for power at the resistor pack and you should be checking for power at the injector leads. To determine if the ECU is attempting to fire the injector, you should be looking for a pulsed ground at the injector. The ECU fires the injectors using an rpm signal from the coil. If I am wrong, I apologize.
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Wildthings
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| Posted: Fri Nov 20, 2015 12:07 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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| MarkWard wrote: |
| If I am wrong, I apologize. |
Your explanation is basically correct, except that on a aircooled Vanagon there is no separate resister pack unless I am mistaken, the injectors getting their power directly from the double relay. Not sure when using just a test light if he would see a flicker on the ground (ECU) side of the injectors or not. Maybe with an analog meter he would pick up the fluctuation, but with a cheap digital his reading would probably be all over the place.
The hot side of the injectors should show close to battery voltage while the ECU side should show close to battery voltage with a flicker. There may be a difference in California and Federal models here, so someone will surely correct me if I am wrong.
The injectors are current tracks #14-17 and the fuel injection half of the double relay is current tracks #19-21
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GreenMachineVW
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Posts: 645
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| Posted: Fri Nov 20, 2015 12:30 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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| Wildthings wrote: |
| MarkWard wrote: |
| If I am wrong, I apologize. |
Your explanation is basically correct, except that on a aircooled Vanagon there is no separate resister pack unless I am mistaken, the injectors getting their power directly from the double relay. |
Federal models have a separate resistor pack, CA models do not.
http://www.thesamba.com/vw/classifieds/detail.php?id=1578545 |
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Wildthings
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Posts: 50353
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| Posted: Fri Nov 20, 2015 12:41 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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| GreenMachineVW wrote: |
| Wildthings wrote: |
| MarkWard wrote: |
| If I am wrong, I apologize. |
Your explanation is basically correct, except that on a aircooled Vanagon there is no separate resister pack unless I am mistaken, the injectors getting their power directly from the double relay. |
Federal models have a separate resistor pack, CA models do not.
http://www.thesamba.com/vw/classifieds/detail.php?id=1578545 |
Thanks, wasn't sure if the Federal and California ones were the same or not. |
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jung
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Joined: August 11, 2015
Posts: 103
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| Posted: Fri Nov 20, 2015 1:35 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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Thanks for the inputs. There are more things to check today.
Could you explain this a little bit more ? This is new to me. Do I need to open AFM to do this ? Where should I push ? What the clicking means ?
"push on the vain in the AFM with the key on, and you should hear it click on and off."
I appreciate your answers in advance. |
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jung
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Joined: August 11, 2015
Posts: 103
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| Posted: Fri Nov 20, 2015 2:21 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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This is very informative video for air cooled vanagon. Information about air cooled vanagon is hard to get. A rare one that explains fuel injection components of air cooled vanagon.
https://www.youtube.com/watch?v=Jca2nBNh3GU |
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Wildthings
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Posts: 50353
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| Posted: Fri Nov 20, 2015 3:58 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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| jung wrote: |
Thanks for the inputs. There are more things to check today.
Could you explain this a little bit more ? This is new to me. Do I need to open AFM to do this ? Where should I push ? What the clicking means ?
"push on the vain in the AFM with the key on, and you should hear it click on and off."
I appreciate your answers in advance. |
You need to open up the air filter housing from which you can stick a pencil or dowel rod down into the AFM and use it to open the door/vain. The click will be the fuel pump relay side of the double relay closing. The key needs to be on when you do this. |
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MarkWard
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Posts: 17155
Location: Retired South Florida
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| Posted: Fri Nov 20, 2015 4:03 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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If you had a stethoscope, you could listen to the injectors "pulse" or open and close. That is the clicking I am referring to. I guess we need to know if you have a CA or Federal model. The above diagram shows that the injectors should have 12 volt power from what the diagram is calling the fuel pump relay. In practice, it is referred to as a double relay because it performs to main functions. It powers the fuel pump and it powers the fuel injection. They do fail.
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Wildthings
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| Posted: Fri Nov 20, 2015 4:21 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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| jung wrote: |
This is very informative video for air cooled vanagon. Information about air cooled vanagon is hard to get. A rare one that explains fuel injection components of air cooled vanagon.
https://www.youtube.com/watch?v=Jca2nBNh3GU |
The Vanagon fuel injection system is not much different from the fuel injection system on a Bay Window Transporter. The L-Jetronic system was first used on some Type 4 engines in 1974 and all bus Type 4 engines from 75-79, with minor changes from year to year. |
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jung
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Joined: August 11, 2015
Posts: 103
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| Posted: Fri Nov 20, 2015 4:56 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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Tested
* tested the ground contact for fuel injection which is near distributor.
* 5, 16, 17 pins in ECU are grounded.
* fuel pump runs
* fuel injector itself. I applied only 5V to the injector and it clicks.
* fuel pump relay : I tested by opening air flow meter and it clicks and I could hear running sound ( electric motor running ). I guess this is a fuel pump.
Are fuel injectors supposed to have voltage when fuel pump runs ?
I'm not sure whether this is progress or not but my buzzing sound when away. I put a key on, I heard a buzzing sound for about 5 seconds. But I don't hear that sound anymore. Something is fixed ? Am I suppose to hear the sound ? |
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AZ Landshaper
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Posts: 1698
Location: The Old Pueblo
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| Posted: Fri Nov 20, 2015 5:53 pm Post subject: Re: Air-cooled: Very low voltage on fuel injectors |
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You need an AFC manual. Here's the link. Tests for the whole system are in there. http://www.thesamba.com/vw/archives/manuals/afc_fi...Manual.pdf
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