81 GLi Fuel Pump Not Priming

So my 81 GLi project lives next to the house under a cover, i went to start it yesterday evening to move it but the fuel pumps not working.

It doesn't prime or anything, i have checked the four pin silver relay which is clicking, i have not yet checked this with a test lead, but i would assume this will be fine. I imagine the pump has got lazy? It has fuel, do these only use an in tank fuel pump?
It usually starts fine, just doesn't run very well! I havn't started it for a couple of months due to dark evenings/bad weather/lack of weekends. But it spent the last four years sat untouched in a damp garage, when i attached a fresh battery it started fine.

My plan this evening is to check for power at the tank connections, check the operation of the relay, give the pump a tap, anything else? I was making progress with the thing before christmas!

Its an external pump in front of the rear drivers side wheel.

So there is no power at the pump, the relay has power and is working correctly, i removed the far left connection on the back of the fuse board (has the correct red/yellow wire) and cleaned the contacts with contact cleaner. But no luck.

The loom runs down the passenger sill, where does the wiring for the pump run?
The interiors stripped out but i can't spot it!

the pump wiring runs down the a pillar and along the sill, then it runs along the front of the rear seat to the passenger side and thru a hole in the seat pan

the fuel relay needs a rev counter signal from the coil to work so check that (red/black wire) and not all of the relays will prime the pump the main thing is it runs while cranking

rubjonny said

the pump wiring runs down the a pillar and along the sill, then it runs along the front of the rear seat to the passenger side and thru a hole in the seat pan the fuel relay needs a rev counter signal from the coil to work so check that (red/black wire) and not all of the relays will prime the pump the main thing is it runs while cranking

Thats interesting thanks Jonny, it always used to prime when the ignition was switched on, but the guages have worked on/off for a while now. I havn't got to the 'remove dash, weld scuttle tray and sort wiring' stage on my to do list yet.
I'll start looking at the coil/rev counter wiring next.
 

You could also remove the fuel pump relay and get a bit of wire and short out the 2 larger connections, this will make your pump run all the time.
I used this method to get me home when my relay failed on the way home.

I've had a theory for a whi8le that the prime happens when the coil sends a single spark on 1st turn of the key, I've seen some do this and if they do perhaps its enough to trick the fuel pump relay into thinking the engine has turned over?  I could be wrong and it may be there is something inside the relay that does the priming thing.

anyway if the above is true perhaps the coil isnt getting power, and this is stopping the initial spark/prime plus no more rev pulse when cranking due to the same issue…

or its the coil -ve wire which is affecting both in the same way

Interesting, well i did try cranking it over for a bit just in case something made the pump live.

I have not yet checked for a spark, looks like i've got to spend some quality! time with the wiring!

Come to think of it, there's the remnants of an 80's immobilizer mounted to the dash, i always thought it must be disconnected, but it might not be!

So i managed to get some time with the old thing finally tonight with a big mug of tea, flood lamp and inspection lamp.

Pics because they make it more interesting:


I have removed the clocks, there is no obvious damage to the wiring, i cleaned the contacts and now the ignition light and oil lamp do come on with the ignition. It does go off though on some turns of the key, a wriggle to the clocks plug gets them working. The digital clock is completely dead though.

The immobiliser has turned out to be just an alarm, scotch locked onto the dash wiring with 7 core towing cable going through the bulkhead for a siren. I've cut this out. Proper retro thing, its left two holes in the dash though!





There is no damage to the wiring running to the pump, and the relay had power at three terminals with the ignition on, it clicks on/off correctly. Fuse 9 was blown, probably the radio one though?

Going behind the fuse box, these look questionable:

This appears to have a red/yellow wire like the fuel pump wire going into it though, is this the fuel pump wiring? Sorry for the rubbish photo…


I quit for the night at that point!

When removing the dash, does the knee bar come out first? I need to get the dash out anyway for some welding…

yeah the 3 way spade thingy is your fuel pump power terminal, 1 spade from fusebox output from relay, 1 to pump and last one is for the wur/aav power.

what are the plug and pin positions and wire colours on the burnt out pins?

fuse 9 is for the horns and reversing lights. #7 does the clock and ciggy lighter so check that and for power at the lighter. does sound like your dash plug is bad though, if the pins are all straight and tight it could be the pcb contact pads

for the knee bar look either end behind it there are big bolts into the a pillars

Excellent, i'll take that apart then, unless its the plastic thats discoloured it looks a bit mucky in there.

I want to get back under and test for power at the pump again, i checked both terminals when i was there last and there was no power. However i am sure i heard a dull click from the fuel pump area a couple of times when the ignition was switched on, with the clocks working.
The issue being its back in its corner by the house, drivers side and rear panel about an inch away from the wall/shed, theres about 30cm space down the passenger side to get to it, so no room to jack up! Since the drums are binding its a heavy old thing to shift too. It has a gateway about a meter in front of it that it only just fits through, so i need someone to steer if i tug it out.

I can't remember the wiring colours off the top of my head, but i did check if they were red/yellow as per the fuel pump wire, i know one was grey.

Sorry i meant to say fuse 8 was blown! I've looked it up to be turn signals and indicator light? The cigarette lighter does work (well the tyre pump runs off it anyway!).
The indicator warning light does sometimes glow dull when the ignition is on too?
No dash illumination has ever worked too, lots of gremlins, i'll get the dash out and get cracking. Just ordered a new 12v tester. Left mine in it and its dissapeared!?

I have to say the contact pads did look ok,, i will perservere, a set of clocks isn't the end of the world though. I have some spare Mk2 Polo non tacko clocks in Devon which i can grab to try next time i'm home.

Excellent, i'll get that out tonight, access to the fuse box will be far easier For the main dash removal, remove glovebox then? I need to start studying the haynes…


Just realised i should have put this in electrical really!


 

aye thats the indicator one, top suspect for this is the ignition live blue/black wire has fallen off the back of the hazard switch and shorted out. goes to pin 15 of the switch

Excellent, i'll have a look.

I also found why the horn would go off randomly whilst steering. The little spring present when the wheel is taken off, that holds the cancelling bits was free and loose. Looks like its been touching the horn ring and the centre of the column.

Looking at a diagram now, there are two fuel pump related relays.

1. Fuel Pump 321906059C (16a fuse)
2. Fuel Pump Relay Bypass Adapter 171971761B

There is a larger black relay with a red ceramic fuse mounted on top, so this is fuel related?

Also the Haynes diagrams in the brown manuals are blooming confusing, any better ones? My brain is turning to mush…

on some you see the fuel relay mounted above the fusebox, with a plug in adaptor to the old relay socket L. the reason for this is they were prone to melting the fuel relay power pin A/8, which is why i was interested to see which ones were burnt on yours!

the stock fuel relay will have a fuse stuck in the end of it yes, so by the sounds of it you have this retrofit kit. if one of the burnt pins on the back is A/8 you can ignore that one, and only worry about the other burnt pin

I see, well i've been going from this:
http://www.google.fr/imgres?imgurl=http%3A%2F%2Fwww.cabby-info.com%2Fimages%2FElectrical%2F80-82FusePanel.png&imgrefurl=http%3A%2F%2Fwww.cabby-info.com%2Felectrical.htm&h=848&w=800&tbnid=Ch6ASuLgtBTdoM%3A&zoom=1&docid=qtZx2yBV6McSnM&ei=9X7sVPetCsXOaLC7gpgF&tbm=isch&iact=rc&uact=3&dur=704&page=1&start=0&ndsp=21&ved=0CCEQrQMwAA

All this time i have been talking about a small, silver box relay, 4 pin that clicks with the ignition. This is mounted on the fuse box next to the relay with a fuse. No relays are mounted to the side of the fuse box.
There four relays in a row, the silver one on the left hand side, i think one in from the end, the others all following.

More investigating and photos with much confusement tonight i'm sure.

the VW (what haynes use!) diagrams i prefer to most others, just a case of understanding what they are on about, this may help:
http://www.clubgti.com/showthread.php?173722

as for the diagram yeah in slot L you either have the fuel relay or you have the relay bypass kit jumper depending if its been done or not:
http://www.cabby-info.com/images/Electrical/FPRbypass.jpg

www.classic-vw.co.uk do the kit if you need it I think, its one of the bits that hasnt made it to the site yet if so. drop him an email

the plain metal one in K is the load reduction relay, what it does is disable high current devices such as the blower, wipers, lights etc while crankign over. if these things work fine you dont have to worry about this relay

Now i feel like an idiot, i've been playing with the wrong relay

I spent a long time sorting out the fuel pump problems on my Polo GT, this uses a little silver box relay for the fuel pump, i just assumed….

I'll do a progress report tonight after some investigation

Well i got it to splutter showing some life!

So heres the fuse box:


I started to pull the terminals out of the three spade terminal junction, one wire pulled out the terminal. This wire turned out to be one that was burnt in the connector to the fuse box:

So i chopped and remade this so it was all connected.

Heres the backs of the damaged plugs:



At this stage i removed the knee bar, fudge thats heavier than i expected. A-post crash strengthening?

I checked the correct relay over this time, with the cover off and working the solenoid nothing happened. However i removed the relay and bridged the main wires, the pump made a dull thud, the same as happened yesterday a couple of times as mentioned above.
I did this a few times, then left the wire connected, the pump continuously clicked, but not the buzz it used to do. I turned the engine over and it fired and ran for a second, then would die. This was repeated until the battery died.

So, i've got more searching to do, however run and die problem is very similar to what it has been doing, just worse. The pump used to buzz though. It does have fuel, i'm just not sure how much, i'll get a can and pour into it.

So lazy pump on that front? Its pay day tomorrow so i'll get a fuel filter on the way, am i better with a s/h genuine pump rather than a new pattern? Should i wait to see if the pump cures with a fresh filter?

And heres the dull indicator light, the hazard and indicators are all off.

right next step is have a word with classic-vw see if you can get yourself a relay bypass, chances are if the pin has melted you have internal fusebox damage which could be reducing available current to pump and giving you these problems. either that or the fuel pump is dead and this is what killed the wire and fusebox plug, or a little of both!

the relay may well want replacing so if classic-vw do those as well I'd have one.

as for the indicator problem, check the wire to hazard switch i mention then repalce the fuse

aye the knee bar is a heavy old lump, its needed to re-inforce the cabrio shells after the roof is chopped out

Excellent, well i've emailed him so i'll wait for a reply, looks like the next opportunity to play with it will be Sunday, so i'll try and get some bits by then.

Do fuel filters differ between early and late K-jet models, or are they the same?

Yes the sodding thing almost beheaded me!