For a while now, I've been trying to diagnose a problem with my fuel pump (on my Mk1 Golf). Sometimes it doesn't start.

I've replaced the fuse, relay and the pump its self, but have still had the problem.

Out of frustration, I dis-mounted the fuse box and looked behind it to see if anything was out of sorts. It was a rats nest of wires but I just made sure that every clip and plug was pushed into its socket tight and securely. Tried the car one more time and it fired up straight away!

So, there is obviously something wrong with the connections going into the back of the fuse box. Question is, how can I clean and secure them without taking the whole thing apart (definitely not confident enough to do that!). Should I use compressed air to clean each socket and plug? Is there some other technique or tool I can use?

  • Did you notice anything as you checked the "clips and plugs" – did anything move or snap into place?
    – dlu
    Feb 7, 2017 at 1:54
  • @dlu no, they all seemed secure, clean and in place.
    – MeltingDog
    Feb 7, 2017 at 3:08

1 Answer 1


It is difficult to say only with this information but your contacts may have some sort of oxidation. Since your car is now working, it would be difficult to diagnose the problem.

Go to some electronics shop and obtain 'contact cleaner' and 'contact grease'. You can remove each plug one by one and look inside to see the situation and clean and then grease and put back.

But in my experience usually contact cleaners do not do much job, you may need to clean/scrape the contacts carefully with a needle or something like that. It may also help to plug them in and out few times after spraying with cleaner.

It would be useful to first figure out which plug is the one you are interested in. You may focus on that plug, although it is probably worthwhile to clean all plugs while on it.

If nothing works, come back and give us more info :)

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