Burnt out multi-plug (fuel pump feed)

[jimmy h]

Would love some advice on how I can sort this mess out?


Basicaly its a problem I've had with the car all the time I've owned it.

It would be nice to know what is causing it and how to fix it?

[ianaudia4]

Do you have a knackered fuse box that is causing the problem, may be worth changing?

[jimmy h]

Do you have a knackered fuse box that is causing the problem, may be worth changing?

Changed the fuse box... :(

It always used to go through fuel pump relays (about one a year) then it burnt out the wire which I fixed by soldering a new bit in.

So I changed the fuse box and it did this?

I've sent a request to Crazy Quiffs in the hope they might be able to supply a second-hand plug off an old loom.

I'm putting a new pump on the car before it goes back on the road, but I would like to know what is causing this exscessive current draw?

[jimmy h]

The guys at Crazy Quiffs have sorted me out with a new plug.

They advise that it is a common fault, either Fuse box - poor connection or corroded interior contacts? or the wires going to the pump are corroded/ breaking down due to age - I will renew (wires) for piece of mind at least - and the new pump.

I'll probs then buy a clip-on ammeter and get an idea what the pump is drawing before I decide it's time for another new fuse-box!

[PeteGLi]

Aah, the dreaded Pin A8.
Ask Ant how he solved it on the Storm he had.
VW had an adapter to relocate the fuel pump relay on the Mark 1, but it went obsolete a long time ago.
They do crop up occasionally - I managed to pick one up from US ebay.

[chopperoli]

I had this problem on my Mk1. I can make you a plug in relocation harness like Pete described, that fixed it for me. The small pin A8 can't take the current

[jimmy h]

I had this problem on my Mk1. I can make you a plug in relocation harness like Pete described, that fixed it for me. The small pin A8 can't take the current

Many thanks, this sounds massively encouraging!

It's heartbreaking in itself to go to the lengths that I'm going to (on this project), with the knowledge that I could be eventually let down in the future with this issue

PM me your details and I'll be in touch, can I discuss on the phone?

Cheers Jim.

[chopperoli]

Yes sure thing. A new plug will just melt again.ask me how I know.

[dingorocco]

Jim, I have just done a carb to K jet conversion on a Mk1 goof.

To overcome the A8 cooked terminal problem, I ran an extra wire from A8 up to a Mk2 fuel pump relay ( triggering circuit ) The power for the Mk2 relay pump feed comes from an unused "H" terminal, then through a 16 Amp fuse. The switched power out of the Mk2 relay then goes to the pump.

Reasoning :- A8 supplies power to the fuel pump, Auxillary air reg and control pressure reg, the fuel pump being the greatest load on the system. When the pump is under max current draw ( sucking dirty fuel, tank screen blocked, fuel level LOW corroded wiring terminals, dodge earth etc ) it then overheats the terminal in the wiring block resulting in the cooking as you see.

Using the output from A8 to trigger a seperate fuel pump relay that supplies power to only the fuel pump should alleviate the melted plug. This car has only done about 30 Km since rebuild, so only time will tell.

I will get some pics when the car comes back for oil change #1 and a trip to the dyno.

LMK if you want a wiring diagram.

cheers,
Grant

Tool for removing the pins :- Top of the page
http://www.vehicle-wiring-products.eu/V ... gterms.php.

[jimmy h]

Grant,

You have a PM.

[dingorocco]

And you have a reply ;)

[dingorocco]

Pics of piggyback Mk2 fuel pump relay used to run just the pump.


New 16 Amp fuse in VW additional fuse block above relay plate.
Additional Mk2 fuel pump relay mounted in factory socket above relay plate ( relay18)

Rear of relay plate showing the wiring .


Power to the fuse was from one of the spare terminal H outlets ( RED , powered all the time)
This then goes to the fuel pump relay switched power in ( RED )
Power out is RED / YELLOW that goes down the back to the pump.
Relay contact power is from the A8 wire of terminal block A ( GREEN/BLACK) A* still needs to go to the other items in the engine bay also.
Contact power is earthed at the back of the relay plate chassis mounts ( BROWN )

The way I see it, using the original fuel pump only switches power to the Mk2 pump letting the higher load being taken care of by the new wiring.
Check the earth on the fuel pump itself, bad ground can be a cause of poor current flow.

HTH.

[steveb]

Old thread but, i have pin 8 burnt out on my MK 1 storm, would this also stop the engine getting a spark ? The car has not run for 10 plus years...... Previous owner had soldered a feed to a fuse in the top of the fuel pump relay

Not sure if the original had a fused relay, i have ordered a manual to assist.

[chopperoli]

Very creative. I don't think it would affect the ignition circuit. But the other way around, if the relay doesn't see a coil pulse signal it won't run the fuel pump.

Old part number for relay relocate harness mentioned in this thread was 171 971 761 B but unlikely still available. Lots of info on other old forums if you search so you can make your own e.g. https://www.vwvortex.com/threads/import ... 000/page-3

And yes original relay had a fuse (part number 321 906 059 C). If you move the relay to be external to the fusebox, you can run any fuel pump relay you fancy (add external fuse if needed)

good luck

[steveb]

Thanks