Fuel Pump Relay 'Problem' - Mk1 Golf GTi 1.8

Hi - apologies if there is an answer (I took a quick look and don't think it's fully covered anywhere)

My Golf won't start

That's the easy bit Basically it's the fuel pump not pumping. The pump works and the engine runs like a train when the relay terminals are bridged.  Obviously doing this leaves the pump running with the ignition off, so not a good work-around.

The relay has been replaced - no joy there.  The relay I has sold doesn't have a fuse on top as described in Haynes (but has all five terminals).

I suspect there is a problem with a signal getting to the relay, but don't know enough about vehicle electrics to even begin to know where to start.

When the engine is running the rev counter works (don't know if this is significant, but it may point to a signal from somewhere being Ok).

Help will be greatly appreciated - thanks 

what fusebox do you have, the early ceramic fuse type or later blade type? the later fusebox dont have the fuse on the relay so I assume late?

the relay is triggered by the rev counter signal from the coil, the fact your rev counter works suggests this is fine but if someone has bypassed the fusebox this could be the issue.

if the wiring to fusebox is ok then it would seem the signal isnt getting to the relay socket, perhaps it has suffered water damage? the revo pin on the relay is 31b, so look at the corresponding socket on FB for obvious damage

Many thanks - that helps narrow it down.  Water damage is suspected as quite wet down there from recent rain - although nothing obvious found.

Yes it is the later blade type FB.

to get you motoring you can replace it with a 17/18 relay from mk1/2/3 which will (should!!) make the fuel relay come on with the ignition. its not 100% safe as it wont cut out in a crash but better than having a jumper wire hanging out the front!

if the 18 relay doesnt work then this points to either the ignition live or earth terminal in the fuel relay socket at fault, rather than the rev counter signal

Thanks for the info - I have driven it with a jumper and scrambled under the dash each time I park!

TBH - searching the forum I found the 17/18 relay in other posts.

Thanks again  

BTW - perfect advice.  Connection to the back of the fuse-box, sorted now.

Next job fit the 16V master-cylinder & servo  

BTW - perfect advice.  Connection to the back of the fuse-box, sorted now.

Next job fit the 16V master-cylinder & servo  

good stuff

Hi, I've a mk 1 1.8 8v cab, I've a fuel pump issue, car only running few days ago, now pump won't even prime off of key, I've changed the relay and I can hear it click but no change, any ideas what prob could be or how I can check pump before I buy a new one? Many thanks

Max13082011 said

Hi, I've a mk 1 1.8 8v cab, I've a fuel pump issue, car only running few days ago, now pump won't even prime off of key, I've changed the relay and I can hear it click but no change, any ideas what prob could be or how I can check pump before I buy a new one? Many thanks

they dont always prime, but to check the fuel pump and wiring swap the 17/18 relay into the fuel pump socket and the fuel pump should always be on with the ignition. if so look at the relay and the rev counter wire as above, if not look at the fuel pump and wiring from it.

if the cab is post-84 it has 2 fuel pumps 1 in the tank and one under the car, if the tank one fails the main pump will eventually die as well

rubjonny said

they dont always prime, but to check the fuel pump and wiring swap the 17/18 relay into the fuel pump socket and the fuel pump should always be on with the ignition. if so look at the relay and the rev counter wire as above, if not look at the fuel pump and wiring from it.

if the cab is post-84 it has 2 fuel pumps 1 in the tank and one under the car, if the tank one fails the main pump will eventually die as well

Resurrecting an old post but just found this when trying to sort why my car wouldn't start today and I couldn't hear the fuel pump,prime when switching ignition on.  Using the no 17 fuse it fired up straight away, so just ordered a new fuel pump relay.  Thanks for your tip rubjonny  

no problems

Having a similar issue with my cabby , I’ve tried two new relays from gsf and pump isn’t coming on when I bridge with a jumper wire it works


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try a 17/18/100 relay in slot 2. if it works, then its the rev counter signal from the coil

Thanks rj


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My car has relay nr 2 in the fuel pump relay. When i turn on the ignition, the fuel pump works for 1 or 2 seconds and it stops. With the relay 17 in the same spot, the pump is always working (2 pumps - my car is from 1.8 DX cabrio 1985).

Which one should i install in the fuel pump relay spot?

relay 2 is the one you want, 17 is only used for testing purposes. 2 is triggered by rev counter signal from the coil, 17 is ignition switched and wont cut out if you crash

Hello! Hope anyone answer.
Ive got a similar problem with my 1984 gti 8v mk2.

Its hard to start when its cold. I have to use a "startgas" to help it start. Ive unplugged the coldstart valve contact and used a multimeter but it seem dead. It only went to 0.89v when it should go to 9v?
My questions are. Where does the wires goes? Is it a ground issue? Are there any relay to this? Ive read there is a relay 43/53??
I took relay 43 out once beacuse my watertemp went crazy. Does this have anything to do with this?

The 5th injector gets power either direct from a black wire to starter motor terminal 15a or red/black wire from fusebox c/18 depending on age. Check the earth green/white as well as the live though, this is fed through the 5th injector thermoswitch which could be broken or you could have issues with the wiring