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Digifant fuel pump relay question.
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zoti
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PostPosted: Thu Jul 30, 2020 10:43 pm    Post subject: Digifant fuel pump relay question. Reply with quote

On my 79 beetle with FI there is a safety system where if the flap on the AIr Flow Meter is not moved, the double relay that supplies power to the fuel pump, will not power the pump.

Is there a similar system on the digifant engines? I turned the key in my 88 and fuel is running all the time. I expect the pump to run only when starting and when the engine is running.

I couldn’t find anything about it in the Bentley.
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PostPosted: Thu Jul 30, 2020 11:20 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

As with your Beetle, subsequent FI systems require that the engine be running for fuel pump to run. Digifant does not have a switch at AFM flap. If I'm not mistaken, once engine is running, Digifant uses a signal from dizzy hall to keep fuel pump on. That detail might be laid out, or referenced in some other explanation, in Bentley 'supplement' section or in the Digifant Pro manual.

When key turned to ignition on, (engine off), your '88 Vanagon fuel pump should run for about just less than a second to prime the fuel system. I'd guess the Beetle FI system does same.

From your description, I'd guess that your Beetle uses the same FI system as used on the air cooled 2.0 in late Bay and air cooled Vanagons.

Neil.
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zoti
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PostPosted: Thu Jul 30, 2020 11:39 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

I know the previous owner did jump a couple of wires where the relay is so I will need to check.

The beetle uses the Bosch L-Jet system. It’s a lot simpler but there are a lot of similarities.

I’m working on the fuel system and wasn’t expecting fuel to spill out of the hose when I turned the key. I will need to check exactly what is going on.
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PostPosted: Fri Jul 31, 2020 12:00 am    Post subject: Re: Digifant fuel pump relay question. Reply with quote

With the '88's Vanagon's Digifant system, the fuel pump is energized when you turn the key to the ON position and will run for about 2 seconds to assure the fuel system is pressurized and ready for the van to start. Then it will shut off automatically if you don't immediately proceed past the ON position to the START position.

If yours is continuing to run while the key is in the ON position, you have a problem.

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zoti
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PostPosted: Fri Jul 31, 2020 12:33 am    Post subject: Re: Digifant fuel pump relay question. Reply with quote

What happens when the van is running and the key is in the on position but the engine quits. Does the fuel pump keep running?
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PostPosted: Fri Jul 31, 2020 2:23 am    Post subject: Re: Digifant fuel pump relay question. Reply with quote

The Digifant ECU controls the fuel pump relay and turns off the relay if it sees that the engine has stopped turning.

If yours runs all the time when the key is on then someone likely modified the wiring for the pump or the pump relay.

When you turn on the key the ECU turns on the pump relay for 1-2 seconds and then turns it off. It won't turn it back on until it sees pulses from the hall unit in the distributor. That is how the ECU knows if the engine is turning.

(note: the Digifant has an idle control valve in the engine compartment and this makes a buzzing sound. On many vans this buzzes all the time when the key is on. You may hear this and think it is the fuel pump you are hearing.)

Mark

zoti wrote:
What happens when the van is running and the key is in the on position but the engine quits. Does the fuel pump keep running?
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Vanagon Nut
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PostPosted: Fri Jul 31, 2020 10:50 am    Post subject: Re: Digifant fuel pump relay question. Reply with quote

Vanagon Nut wrote:
....Digifant does not have a switch at AFM flap. If I'm not mistaken, once engine is running, Digifant uses [edit: requires] a signal from dizzy hall to keep fuel pump on. .....

When key turned to ignition on, (engine off), your '88 Vanagon fuel pump should run for about just less than a second to prime the fuel system. I'd guess the Beetle FI system does same.

zoti wrote:
I know the previous owner did jump a couple of wires where the relay is so I will need to check.

The beetle uses the Bosch L-Jet system. It’s a lot simpler but there are a lot of similarities.

I’m working on the fuel system and wasn’t expecting fuel to spill out of the hose when I turned the key. I will need to check exactly what is going on.


I won't speculate on exactly how I think the fuel pump wiring may've been altered but it sounds like you're quite familiar with L-jet so I'm sure you'll figure this out. If it was me, I'd look for:

- added wire to black ignition coil wire (15)

or

- alteration of Digifant relay 87, fuel pump relay 87.


Neil.
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1981 Westy air cooled to 15º ABA swap: http://tinyurl.com/y9n4xob8

50º ABA Swap in to '88 Westy: http://tinyurl.com/yap5hpwt

Vanagon VAG GAS engine swap Google Group:
https://tinyurl.com/2f24rmh

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kamzcab86
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PostPosted: Fri Jul 31, 2020 1:31 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

Vanagon Nut wrote:

- alteration of Digifant relay 87, fuel pump relay 87.


The '88/'89 vans do not have the same Digifant relay as all others, unless it's been modified like what I did to my parents' van:
https://www.thesamba.com/vw/forum/viewtopic.php?p=9166826#9166826 .

As previously mentioned to the OP, it would be wise to convert the 5-pin Digi relay (which is NLA) to a 4-pin like all the other vans.
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zoti
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PostPosted: Fri Jul 31, 2020 1:52 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

kamzcab86 wrote:
Vanagon Nut wrote:

- alteration of Digifant relay 87, fuel pump relay 87.


The '88/'89 vans do not have the same Digifant relay as all others, unless it's been modified like what I did to my parents' van:
https://www.thesamba.com/vw/forum/viewtopic.php?p=9166826#9166826 .

As previously mentioned to the OP, it would be wise to convert the 5-pin Digi relay (which is NLA) to a 4-pin like all the other vans.


I will need to dig deeper but I can do that only after I fix the leaking fuel lines and I need to get the idle to stabilize first. I would love to hear about the conversion from 5 to 4 pin.
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PostPosted: Fri Jul 31, 2020 2:21 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

kamzcab86 wrote:
Vanagon Nut wrote:

- alteration of Digifant relay 87, fuel pump relay 87.


The '88/'89 vans do not have the same Digifant relay as all others, unless it's been modified like what I did to my parents' van:
https://www.thesamba.com/vw/forum/viewtopic.php?p=9166826#9166826 .


Good point, thanks for catching that. I have an '88 which appears to use use '87 wiring (and has a 4 pin relay). I usually look at the '87 diagrams for my bus and did so for the OP's. Old habit. Wink

Neil.
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1981 Westy air cooled to 15º ABA swap: http://tinyurl.com/y9n4xob8

50º ABA Swap in to '88 Westy: http://tinyurl.com/yap5hpwt

Vanagon VAG GAS engine swap Google Group:
https://tinyurl.com/2f24rmh

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zoti
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PostPosted: Fri Jul 31, 2020 3:29 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

I'll take a picture of what I have and post it.
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zoti
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PostPosted: Sat Aug 01, 2020 9:30 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

I took some pictures of what is going on in the fuel pump relay box. Previous owner told me he converted from 5 wire to a 4 wire setup removing the expensive relay.

The black and white wire is disconnected. I am going to clean up everything and cover with insulating tape. Just want to see if it was done correctly.

Anyone know the link to the conversion thread?


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PostPosted: Sun Aug 02, 2020 1:51 am    Post subject: Re: Digifant fuel pump relay question. Reply with quote

zoti wrote:
Anyone know the link to the conversion thread?


Already posted, but here it is again: https://www.thesamba.com/vw/forum/viewtopic.php?p=9167841#9167841 .

See it visually via wiring diagrams in the revised ProTraining Manual: http://oldbluesblog.com/files/DigifantProTrainingManual_SingleSided.pdf .
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Vanagon Nut
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PostPosted: Sun Aug 02, 2020 11:20 am    Post subject: Re: Digifant fuel pump relay question. Reply with quote

The red/yellow wire contact at fuel pump relay socket looks like it's getting pushed out by insertion of relay; those contacts have a locking tab to keep them in place.

The black sh107 relay looks like it does not have a suppression device. Suggest using a properly Amp rated relay with suppression device. (resistor) The diagram on relay will indicate if it has a resistor across 85/86.

Heat from soldering done on the red 30 wire (why was it cut?) might've damaged the black switched positive wire but the red 30 wire looks like its' also suffered heat damage where it enters the box. But, that clue may be a red herring as I doubt the current limit of it was exceeded but I'd be curious about that.

Comparing wiring to pin 87 of each relay socket, it looks like this harness uses the 1990 year scheme which I find interesting.

Since your fuel pump runs when key is turned to ignition on (engine off), at forward end of engine bay, look for the white 2 pin connector for fuel pump. Maybe someone hacked wiring to that?

Neil.
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1981 Westy air cooled to 15º ABA swap: http://tinyurl.com/y9n4xob8

50º ABA Swap in to '88 Westy: http://tinyurl.com/yap5hpwt

Vanagon VAG GAS engine swap Google Group:
https://tinyurl.com/2f24rmh

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zoti
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PostPosted: Sun Aug 02, 2020 12:27 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

Vanagon Nut wrote:
The red/yellow wire contact at fuel pump relay socket looks like it's getting pushed out by insertion of relay; those contacts have a locking tab to keep them in place.

The black sh107 relay looks like it does not have a suppression device. Suggest using a properly Amp rated relay with suppression device. (resistor) The diagram on relay will indicate if it has a resistor across 85/86.

Heat from soldering done on the red 30 wire (why was it cut?) might've damaged the black switched positive wire but the red 30 wire looks like its' also suffered heat damage where it enters the box. But, that clue may be a red herring as I doubt the current limit of it was exceeded but I'd be curious about that.

Comparing wiring to pin 87 of each relay socket, it looks like this harness uses the 1990 year scheme which I find interesting.

Since your fuel pump runs when key is turned to ignition on (engine off), at forward end of engine bay, look for the white 2 pin connector for fuel pump. Maybe someone hacked wiring to that?

Neil.


The previous owner made some changes and I want to do the 4 pin conversion. By the BK/W wire being disconnected I think he steady did that.

What is the correct relay to get?

I want to repair all the wires and insulate them.
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PostPosted: Sun Aug 02, 2020 12:39 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

From what I can see, terminal 87a on the fuel pump relay is connected now to terminal 30 on the digifant relay.

The black and white wire was disconnected from the relays and I think the black wire was moved to terminal 86 from terminal 87a.

Is that how it should be? If it is, then I will just Repair the damaged wires.



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PostPosted: Sun Aug 02, 2020 1:49 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

Got all the wires covered. Much better.


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PostPosted: Sun Aug 02, 2020 2:00 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

zoti wrote:
Vanagon Nut wrote:
Suggest using a properly Amp rated relay with suppression device. (resistor) The diagram on relay will indicate if it has a resistor across 85/86.

.... but the red 30 wire looks like its' also suffered heat damage where it enters the box. .... I'd be curious about that.

Since your fuel pump runs when key is turned to ignition on (engine off), at forward end of engine bay, look for the white 2 pin connector for fuel pump. Maybe someone hacked wiring to that?

Neil.


The previous owner made some changes and I want to do the 4 pin conversion. By the BK/W wire being disconnected I think he steady did that.

What is the correct relay to get?

I want to repair all the wires and insulate them.

From what I can see, terminal 87a on the fuel pump relay is connected now to terminal 30 on the digifant relay.

The black and white wire was disconnected from the relays and I think the black wire was moved to terminal 86 from terminal 87a.

Is that how it should be? If it is, then I will just Repair the damaged wires.


I've never done that conversion but I agree; that conversion appears to have been done.

Your "Made in Germany" relay is likely a "53" which is typically used in fuel pump and "Digifant" positions. You could find it online but I'd bring your 53 relay to your FLAPS to help match it to a generic 12 volts properly Amp rated 4 pin relay with suppression device. That black relay should work for now but every time you shut off the engine, it might allow voltage spikes to harm the ECU.

crazyvwvanman comments in link Kamz provided will be accurate and will cover at least part of what I'll try to explain but here goes.....

The black relay has 4 pins so there should be no 87a involved here. And AFAIK, a 30/87 85/86 relay pinout is standardized. So, I doubt that 30 and 87 positions are reversed on that relay.

I don't see a connection between a 30 and 87. If 30 was connected to fuel pump relay 87, the fuel pump would run all the time. I sometimes label the 30/87 85/86 pins on the relay housing so I know what female pin is what at socket. Not easy to see the numbers on the black sockets.

The black switched positive wires originally went to pin 5 of 5 pin relay and 86 of 4 pin relay. To me, they now appear correct: each goes to 86 of each relay. That said, as mentioned, the fuel pump relay is controlled by the ECU.

In your images, it appears that the 30 supply wire from 2 pin connector connects to 30 of each relay which is correct. Below is an image of the harness on my '88. You can see how that red wire originally looked.

A short out event may've caused the damage at red wires from the 2 pin connector. Inspect: red wire from that 2 pin connector back to positive junction stud in the black junction box at driver side of firewall, wires in that box, and wire from that stud to alternator B+ stud.

This has been written about here, but if one of the wires from the power steering switch is not connected and shorts to ground, it could conduct electricity for a relatively long period of time thus do damage to other wires etc. e.g. to wires you show.

Seeing the new image, I'd be prone to replacing the burned wires but to do so, you'd need new used sections of wire with proper contacts or means to make same. In the past I've used wires from new relay sockets for this type of thing but I don't recall if the 2 pin connector has proprietary terminals.

Neil.

This harness has a different wiring design, colours but 30 wires should be the same.

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

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1981 Westy air cooled to 15º ABA swap: http://tinyurl.com/y9n4xob8

50º ABA Swap in to '88 Westy: http://tinyurl.com/yap5hpwt

Vanagon VAG GAS engine swap Google Group:
https://tinyurl.com/2f24rmh

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PostPosted: Sun Aug 02, 2020 2:03 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

Cool. I was going to suggest using heat shrink tube.

Insulate the black/white wire terminal. Diagrams show it connecting to ECU.

Neil.
_________________
1981 Westy air cooled to 15º ABA swap: http://tinyurl.com/y9n4xob8

50º ABA Swap in to '88 Westy: http://tinyurl.com/yap5hpwt

Vanagon VAG GAS engine swap Google Group:
https://tinyurl.com/2f24rmh

VE7TBN
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zoti
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PostPosted: Sun Aug 02, 2020 2:26 pm    Post subject: Re: Digifant fuel pump relay question. Reply with quote

Vanagon Nut wrote:
Cool. I was going to suggest using heat shrink tube.

Insulate the black/white wire terminal. Diagrams show it connecting to ECU.

Neil.


Yes. You are correct. The ref wired is connected to 30 on each relay.

I don’t think there was damage due to a short. It looks like when the PO did the conversion, he poured some hot material on the new connection to insulate it. That material ended up on the other 2 wires melting the insulation.

I also insulated the connector on the BK/W wire with some heat shrink.

If I understand correctly, it should all be good now.

On to the fuel lines. Just got the correct clamps.
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