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'79 CA FI bus ran fine then suddenly won't start
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Tcash
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PostPosted: Mon Sep 11, 2017 8:11 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

I have 13v on pin 15 before I start but it drops to 9 or 10v while turning the engine.
That is a significant voltage drop for the ignition. As suggested test your ignition system.
Points ignitions require 9.6v to operate.
Electronic systems like to see 12v.
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Happyfolk
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PostPosted: Tue Sep 12, 2017 3:14 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

Here's a video of it trying to start:

Link

I feel like it will be something stupid simple in the end. Just need to find it.
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Happyfolk
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PostPosted: Wed Sep 13, 2017 3:08 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

I replaced the coil and it fired right up!


Link

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Last edited by Happyfolk on Fri Sep 15, 2017 7:20 pm; edited 1 time in total
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Tcash
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PostPosted: Wed Sep 13, 2017 8:12 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

Winner Winner Chicken Dinner!

pittwagen wrote:
You might be getting voltage at the coil but are you getting spark at the plugs? I have had both the hall sensor and the control unit fail on a water cooled Rabbit which had a very similar setup to the 79 CA unit I currently have on my bus.

If you can get the Mk2 golf/jetta Bentley manual, check the ignition section. The ignition troubleshooting section is much better that the Bus Bentley one.
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PostPosted: Thu Sep 14, 2017 10:24 am    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

measure voltage at the coil again when cranking. If it is still 9 or 10, then the problem is only masked by the new coil that has a higher secondary voltage. If the voltage is now 12 or very near it then the old coil was pulling too much current from being shorted.
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Happyfolk
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PostPosted: Fri Sep 15, 2017 6:03 am    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

SGKent wrote:
measure voltage at the coil again when cranking. If it is still 9 or 10, then the problem is only masked by the new coil that has a higher secondary voltage. If the voltage is now 12 or very near it then the old coil was pulling too much current from being shorted.


The starter is still causing a voltage drop when being cranked.

I took the bus for a test drive last night and it was running great, but then after five miles it died and I had to coast to the side of the road. It wouldn't fire at all after that. Just cranking from the starter without any hint of firing.

I had a neighbor pull me home with a tow strap that I keep in the bus.
This morning it was cranking and firing but not starting, like before I replaced the coil.

I probably need a new starter. I've had troubles with the solenoid/hot start issue after long hauls. I've removed it and lubed the solenoid a couple of times but still get that issue once in a while. Not too inconvenient to crawl beneath and short the starter contact to free it up, but maybe now's the time to get a new starter. I just got a hot start relay kit to installl, but I'm thinking of going with a newer gear reduction starter with the adapter plate:
http://www.busdepot.com/mt1
http://www.busdepot.com/sr0408xor

But I still seem to have some type of issue going on after starting that seems to be related to engine temperature? I have a new TSII I'm going to install.
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Tcash
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PostPosted: Fri Sep 15, 2017 9:11 am    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

Try this to isolate the problem.
http://www.thesamba.com/vw/forum/viewtopic.php?t=535382&highlight=
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Happyfolk
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PostPosted: Fri Sep 15, 2017 6:26 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

OK, tonight after it cooled down outside I gave it a try and it started right up. Drove it up the driveway and into the garage.
Not fixed but interesting. Just glad to get it into the garage to work on it!
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Wildthings
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PostPosted: Sat Sep 16, 2017 4:21 am    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

It sounds to me like your engine is trying to start off only the fuel from the CSV and once the TTS stops grounding the CSV the engine is no longer getting fuel until the TTS cools again. Try checking your injector pulse or doing a spray test.

The grounds for the ECU need to be good for the injectors to fire.

If you haven't checked the pins in the plug for the ECU, then do so.
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pittwagen
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PostPosted: Sat Sep 16, 2017 11:12 am    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

Does this mean that I might not get to "cash" in on that chicken dinner? My bus still knows its "way to San Jose" having spent most of its life there.

Happyfolk, please tell me you did all the ignition checks. Just to eliminate them as an issue. If I remember, when they went on my water cooled vw, the problem was intermittent followed by total failure.

Parts are still available. The coil and the control unit are the same as the Westmoreland Rabbit and the early Mk2's as well as Euro cabrios. My spares came from a cabrio. Just remember the hall sender plugs are different - oval on the Bus and Vanagon and more rectangular on the water cooled ones. If you go the water cooled route for the hall sender be sure to get the control unit to hall sender wiring harness.
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Tcash
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PostPosted: Sat Sep 16, 2017 1:37 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

Scrambl'z chicken & waffles in style.
Image may have been reduced in size. Click image to view fullscreen.
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PostPosted: Sat Sep 16, 2017 1:45 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

This morning I went through the entire list of ECU connection tests in the AFC manual. Everything looked good except I wasn't getting any voltage to the computer on pin 10.

I then went through the dual relay and had voltage at 86c from the coil but no voltage on 88a, b, e, or f.

There is a grounding wire that came out of the dual relay left (driver) side plug where pin 85 normally is on the Fed/11-pin dual relay and attached to the bolt that holds the relay to the firewall. But on the CA/13-pin relay contact 85 is on the right (passenger) side of the relay and there's no contact in that spot on the left side on the relay.

Until last week the fuel pump contacts on my AFM weren't adjusted properly so my fuel pump always ran as soon as I turned the ignition on, before starting.

I adjusted it so there was 1mm clearance between the contacts so the pump only ran once the starter was engaged or the AFM flap moved.

I don't know how my ECU, AFM, injectors, or Hall Ignition Control Unit ever were getting voltage without pin 85 on the relay grounded? The wire from pin 28 was connected to relay contact 85 but it must not become grounded once the ECU harness is plugged in since the AFM manual has you checking for voltage on pin 10 with it unplugged. I checked resistance from pin 28 on the ECU connector to the other grounds on pins 5, 16, & 17 and didn't detect a connection. There's another brown wire that connects to the grounding wire on the dual relay that comes into the engine bay in a harness through a hole next to the hole that the brake booster hose goes through. I don't see this wire in the schematic so not sure yet where it goes?

I connected the grounding wire that attaches to the bolt that holds the dual relay to the firewall to the plug slot that goes to contact 85 on the right side of the relay. This is the wire that had gone to where pin 85 is on the 11-pin relay but had no contact there on the 13-pin version. Then I also connected the wire from ECU pin 28 to the bolt that holds the relay to the firewall.

I also cleaned up several other connections to get the resistance from one end of a wire to the other down below .5 ohms when it had been 3-5 ohms before.

I'm getting the proper voltage on ECU pin 10 now with the ignition on and the engine fires up very quick and easy and seems to be running well.

11-pin Federal dual relay:
Image may have been reduced in size. Click image to view fullscreen.


13-pin California dual relay:
Image may have been reduced in size. Click image to view fullscreen.

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Last edited by Happyfolk on Sat Sep 16, 2017 2:56 pm; edited 1 time in total
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PostPosted: Sat Sep 16, 2017 2:44 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

Happyfolk wrote:
This morning I went through the entire list of ECU connection tests in the AFC manual. Everything looked good except I wasn't getting any voltage to the computer on pin 10.

I then went through the dual relay and had voltage at 86c from the coil but no voltage on 88a, b, e, or f.

There is a grounding wire that came out of the dual relay left (driver) side plug where pin 85 normally is on the Fed/11-pin dual relay and attached to the bolt that holds the relay to the firewall. But on the CA/13-pin relay contact 85 is on the right (passenger) side of the relay and there's no contact in that spot on the left side on the relay.

Until last week the fuel pump contacts on my AFM weren't adjusted properly so my fuel pump always ran as soon as I turned the ignition on, before starting.

I adjusted it so there was 1mm clearance between the contacts so the pump only ran once the starter was engaged or the AFM flap moved. But the fuel pump was somehow running when I moved the AFM wiper even though relay pin 85 wasn't grounded!!??

I don't know how my computer, AFM, injectors, or Hall Ignition Control Unit ever were getting voltage without pin 85 on the relay grounded? The wire from pin 28 was connected to relay contact 85 but it must not become grounded once the ECU harness is plugged in since the AFM manual has you checking for voltage on pin 10 with it unplugged. I checked resistance from pin 28 on the ECU connector to the other grounds on pins 5, 16, & 17 and didn't detect a connection. There's another brown wire that connects to the grounding wire on the dual relay that comes into the engine bay in a harness through a hole next to the hole that the brake booster hose goes through. I don't see this wire in the schematic so not sure yet where it goes?

I connected the grounding wire that attaches to the bolt that holds the dual relay to the firewall to the plug slot that goes to contact 85 on the right side of the relay. This is the wire that had gone to where pin 85 is on the 11-pin relay but had no contact there on the 13-pin version. Then I also connected the wire from ECU pin 28 to the bolt that holds the relay to the firewall.

I also cleaned up several other connections to get the resistance from one end of a wire to the other down below .5 ohms when it had been 3-5 ohms before.

I'm getting the proper voltage on ECU pin 10 now with the ignition on and the engine fires up very quick and easy and seems to be running well.

11-pin Federal dual relay:
Image may have been reduced in size. Click image to view fullscreen.


13-pin California dual relay:
Image may have been reduced in size. Click image to view fullscreen.

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pittwagen
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PostPosted: Sat Sep 16, 2017 2:52 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

So the relay is grounded to the firewall tin. And how good is the ground between the firewall tin and the bus?

I added a ground wire and attached it directly to the bus underneath and to the side of the BN4.

Image may have been reduced in size. Click image to view fullscreen.
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Wildthings
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PostPosted: Sat Sep 16, 2017 2:56 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

If you were not getting a ground on pin 85 on the DR you would not have heard the relay click as you turned the key on. That would have been a pretty good clue as to where to look. I would guess that the circuit between pin 28 on the ECU and its corresponding ground connection is bad.
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PostPosted: Sat Sep 16, 2017 3:05 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

pittwagen wrote:
So the relay is grounded to the firewall tin. And how good is the ground between the firewall tin and the bus?

I added a ground wire and attached it directly to the bus underneath and to the side of the BN4.


The firewall seems to be grounded well enough, but probably not a bad idea to attach it to the chassis.

Any idea how my bus has been running the last 3 years that I've had it without the relay pin 85 being grounded? Pin 28 on the ECU must've been giving it some grounding once it was plugged in but since the AFM manual has you check for voltage on pin 10 of the ECU connector with it unplugged from the ECU and with the ignition on it must not be the intended source of grounding for relay pin 85. Pin 10 gets its voltage from dual relay pin 88b only after the relay switch closes, which requires pin 85 to be grounded.
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PostPosted: Sat Sep 16, 2017 3:19 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

Wildthings wrote:
If you were not getting a ground on pin 85 on the DR you would not have heard the relay click as you turned the key on. That would have been a pretty good clue as to where to look. I would guess that the circuit between pin 28 on the ECU and its corresponding ground connection is bad.


I was hearing the relay click until the last couple of days. It doesn't make sense. Is pin 28 on the ECU supposed to have another ground connection other than pin 85 on the relay? It doesn't appear so in the schematic. In fact the schematic doesn't show 85 grounded at all but Colin's relay diagram does, which has to be the case.

Image may have been reduced in size. Click image to view fullscreen.

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PostPosted: Sat Sep 16, 2017 4:36 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

Pin 28 should be connected internally inside the ECU to one of the three ground wires. I don't think there would be any problem with your running an external ground though.

Don't know why the Pro Training manual would say that you would have voltage on pin 10 with the plug disconnected. Likely whoever was writing up the manual missed something.
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PostPosted: Sat Sep 16, 2017 5:41 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

If ECU pin 28 connects to ground pins 5, 16, & 17 once plugged in then maybe that wasn't my issue. I wasn't getting the relay to work with the ECU unplugged but was before I unplugged it.

The AFM manual ECU pin test list on page 40 said to check for 12 volts on pin 10 with the key in the ON position, so when I didn't get that I redid the ground connections at the dual relay. Probably just makes a redundant ground which is never a bad thing.

I did clean up some connections including the coil 15 connection to the dual relay. I was getting 4.5 ohms but after cleaning up that connection got it down to .4 ohms. Also improved a few other ground connections. Maybe that's why it was starting and running better afterwards?

Taking it for a test drive tomorrow to see how it drives or if it will die again. Tow strap and neighbor with truck ready on call!

Curious that the pin 28 connection isn't listed on this:
Image may have been reduced in size. Click image to view fullscreen.
[/img]
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PostPosted: Sat Sep 16, 2017 7:23 pm    Post subject: Re: '79 CA FI bus ran fine then suddenly won't start Reply with quote

The 28 pin is shown in use here

https://www.thesamba.com/vw/archives/info/wiring/baybus_79.jpg

and for all aircooled Vanagons in the Vanagon Bentley.

As I said I suspect something was missed when they wrote up the Pro Training Manual for the '79 and later engines. This type of error is very common both with VW and other makes.
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