1989 GTI Cabriolet possible fuel supply issue

My cabriolet has been cutting out whilst driving and I’m wondering if it’s a fuel supply issue. The power will die for a few seconds at a time whilst my foot is on the accelerator and then come back, on one occasion the engine cut out completely and I couldn’t get it to restart. I have replaced the fuel filler neck, fuel filter and had the tank cleaned out.
I replaced the fuel pump relay as when I first bought the car it occasionally wouldn’t start and I was told the relay was the issue and have not had this problem since, however I’m wondering if perhaps I have bought the wrong relay. Could anyone link me to the correct one?
I have ordered a new in tank fuel pump and will trace the wires to check for damage or corrosion.
Has anyone got any other suggestions/possible solutions? Or any way of diagnosing anything else that it might be?
Thanks!!


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Cabby-info.com has the fuel pump relay numbers that work, and how to tell if yours has the bad circuits in it or not.

Thanks [mention]Briano1234 [/mention]
I checked the diagrams and the pin layout is correct but the circuit looks nothing like either of the pictures!


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VW fuel pump relay is No 62

Does the main fuel pump get noisier when the car plays up?

Yes I replaced the no. 62 relay but the replacement doesn’t have a number on it.
I definitely notice a whining noise that sounds like it’s coming from the underside of the car on the side of the filler neck. Any ideas what that could be?


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The whining noise from underneath the car is the main fuel pump, if the fuel pump inside the tank (lift pump) stops working the main fuel pump has to work harder to get the fuel to the engine and makes more noise.
The main fuel pump is not the quietest in the world so don't expect it to be silent.

Did or does the main pump underneath the car get noisier when the problem started?

The lift pump is cheaper and easier to replace than the main fuel pump but it may be worth changing that and see if that helps.

When my lift pump started to fail you could accelerate slowly but if you tried to floor or the car would cough and splutter.

There is also a little bit of rubber fuel hose which joins the lift pump to the fuel sender, as it’s sat in petrol most of the time it can rot so it worth changing that when changing the lift pump. It must be the same length as the original or the fuel pick up will be either to low or to high in the tank. The Haynes manual tells you the length the hose should be.

Lift pump is like this

https://www.ebay.co.uk/itm/200691149226?epid=251916676&hash=item2eba1fe9aa:g:wFYAAOSwcwlfslHy

Have you still got the No62 relay?
The after market fuel pump relays don't seem to be very good quality so fit the VW relay No62 relay if you still have it and keep the unnamed one as a spare in the glove box.

Thanks [mention]mark1gls [/mention], from my memory the noise got louder when the problem occurred however it’s been a while since I’ve driven the car as it’s been in storage for the winter. I have ordered a new in tank fuel pump/lift pump and will have a look at replacing the pipe too.
I’m not sure if I did keep the original relay, I’ll have to look for it


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[mention]mark1gls [/mention] what is the rubber hose you are referring to? Do you have a picture? Thanks!


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Briano1234 has a guide to replacing the lift pump.

The bit of rubber hose I'm talking about the the one that goes from the lift pump to the main body of the sender.

1984.5-1993 mk1 How to change your in-tank fuel pump | Volkswagen Owners Club Forum

Had the same problem with my cabby. Pulled out the lift pump, replaced the little piece of rubber hose with some new fuel hose ( making sure the pump is 175mm overall ) and stuck it back in the tank. Hey presto, no fuel pump whine and car runs sweet again. Worth trying this as a very cheap fix.

[mention]marcsa3 [/mention] thanks, I have bought a new piece of that hose as well as a new pump. From what two points do you measure the 175mm? Do you have a diagram? I’ve ordered the Haynes Manual but it hasn’t arrive yet


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Hi. 175mm is the overall height of the lift pump top to bottom after the new piece of pipe is fitted.
Lift pump can be tricky to get in and out so be careful not to snag the float. Good luck.

to keep the filter in place as you re-install the new pump, use a 3 foot piece of string and tie the strainer on the pump at the top. THEN AFTER GETTING IT IN, prior to locking it down, cut the string and gently pull it up and out.



Some folks won't read the links, so here is a gimmee.

[mention]Briano1234 [/mention] I was going to just cable tie the filter on, do you think it’s okay to keep that there permanently?


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The filter should push on the pump and be tight.
I've not had any problems with it falling off but I'm very careful getting the pump and float out and into the tank.

Something else to be careful with is the rubber O ring which seals the fuel sender in the tank, a little bit of grease helps hold it in place when fitting the sender.

geobuckland said

[mention]Briano1234 [/mention] I was going to just cable tie the filter on, do you think it’s okay to keep that there permanently?


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I had one that was an iffy fit and the third time I dropped it in the tank inserting it, I have the Eureka moment. Just keep it on long enough to get the sender/pump down then either untie it or cut it off and pull the knotted side so the loose side comes all the way out.

Hello, I have been having a very similar issue with my Mk 1 Cab 1992. It doesn't seem to do it when there is a full tank of fuel only 1/2 or below. Does this happen with you? I'm thinking it could be pressure building up in the tank as lots of pressure is released when filler cap is removed…