help,mk3 vr6 keeps popping fuel pump fuses!!!

[B.I.G DUB]

has anyone else had this problem? i had the auto electrician out and he reckoned it was something to do with the lambada sensor having a heater matrix in it that does something to emissions,i replaced the lambada and he said that should cure the problem,but hasnt! the car is a mk3 vr6 1994. this is causing concern as it seems to do it at awkward times,like when over taking,but then does it when im going slow just general driving! somebody plz help as im really worried,is there any chance it could be an earth or something along those lines? any help would be a great help as i am now stumped! 

[[han]]

its defo the right fuse? had a guy who bought 8 fuses before he realised! 

[B.I.G DUB]

i think so?its a higher amp than the 20 that was in it,around 30 amp to try and prolong the mileage im getting,and to see if whats causing the problem actually breaks. really weird?!   

[Len]

Have you replaced the relays?

[B.I.G DUB]

relays? replaced 1 of them,is there more linked to it? 

[GTI EDITION (aka LTD)]

Just had a look at a current flow (wiring) diagram for you VR.
The  fuse SHOULD be a 20A, be very careful putting a higher amperage in place of it as it could bu99er up the wiring etc further up the line  ( remember VW put in a 20A for this exact reason )

This fuse only supplies the lambda probe heater[ G1/8], the fuel pump [M/2] (obviously) there should be nothing else unless someones been connecting wires in  the wrong places. 

Are the wires down by the plug for the lambda sensor OK and not chafing on any thing?

Other than that the fuel pump wiring needs to be checked out and even the pump it's self 

N.B. G1/8 and M/2 refer to the plugs on the back of the relayplate ( or some may say fusebox )

eg G = plug location on relay plate  1= terminal this circuit uses in plug  8= how may terminals the plug actually has 

Hope this has helped in some way and not confused. 

[B.I.G DUB]

it all makes sense except that last paragraph,not sure what u mean? i will put a 20 amp in it now so it is all back to normal.i thought that that wires might be chaffing near to the plug itself so i wrapped the wires in insulting tape to see if that would work but it still happened! the car can go 2miles and stop from cold,i'll replace the fuse and then it will do 25-35 miles before it goes again!?  thanks for all the advice tho,

[rubjonny]

Defo sounds like a damaged wire somewhere, 1st thing I'd do is unplug the lambda probe and see if it still does it!  THe car will run with a default map with the probe unplugged, so you wont get quite as much power/economy but it should still run fine.
If that doesn't solve it the problem lies with the pump or wiring! Lift up the boot carpet and the metal disc in the boot floor.  Follow the wiring from the pump as far as you can checking for kinked or bare wires along the way.

[adyh]

Check your fuel filter as well .

[AudiA8Quattro]

There is no default backup setting if the oxygen sensor is unplugged, so not sure that is a good idea. If you do unplug it, then only leave it unplugged for short periods, otherwise the catalyer could be damaged.
My money is on the fuel pump itself being faulty.